Health psychology

From Wikipedia, the free encyclopedia

Health psychology is the study of psychological and behavioral processes in health, illness, and healthcare. It is concerned with understanding how psychological, behavioral, and cultural factors contribute to physical health and illness. Psychological factors can affect health directly. For example, chronically occurring environmental stressors affecting the hypothalamic–pituitary–adrenal axis, cumulatively, can harm health. Behavioral factors can also affect a person's health. For example, certain behaviors can, over time, harm (smoking or consuming excessive amounts of alcohol) or enhance health (engaging in exercise). Health psychologists take a biopsychosocial approach. In other words, health psychologists understand health to be the product not only of biological processes (e.g., a virus, tumor, etc.) but also of psychological (e.g., thoughts and beliefs), behavioral (e.g., habits), and social processes (e.g., socioeconomic status and ethnicity).

By understanding psychological factors that influence health, and constructively applying that knowledge, health psychologists can improve health by working directly with individual patients or indirectly in large-scale public health programs. In addition, health psychologists can help train other healthcare professionals (e.g., physicians and nurses) to take advantage of the knowledge the discipline has generated, when treating patients. Health psychologists work in a variety of settings: alongside other medical professionals in hospitals and clinics, in public health departments working on large-scale behavior change and health promotion programs, and in universities and medical schools where they teach and conduct research.

Although its early beginnings can be traced to the field of clinical psychology, four different divisions within health psychology and one related field, occupational health psychology (OHP), have developed over time. The four divisions include clinical health psychology, public health psychology, community health psychology, and critical health psychology. Professional organizations for the field of health psychology include Division 38 of the American Psychological Association (APA), the Division of Health Psychology of the British Psychological Society (BPS), and the European Health Psychology Society. Advanced credentialing in the US as a clinical health psychologist is provided through the American Board of Professional Psychology.

Overview

Recent advances in psychological, medical, and physiological research have led to a new way of thinking about health and illness. This conceptualization, which has been labeled the biopsychosocial model, views health and illness as the product of a combination of factors including biological characteristics (e.g., genetic predisposition), behavioral factors (e.g., lifestyle, stress, health beliefs), and social conditions (e.g., cultural influences, family relationships, social support).

Psychologists who strive to understand how biological, behavioral, and social factors influence health and illness are called health psychologists. Health psychologists use their knowledge of psychology and health to promote general well-being and understand physical illness. They are specially trained to help people deal with the psychological and emotional aspects of health and illness. Health psychologists work with many different health care professionals (e.g., physicians, dentists, nurses, physician's assistants, dietitians, social workers, pharmacists, physical and occupational therapists, and chaplains) to conduct research and provide clinical assessments and treatment services. Many health psychologists focus on prevention research and interventions designed to promote healthier lifestyles and try to find ways to encourage people to improve their health. For example, they may help people to lose weight or stop smoking. Health psychologists also use their skills to try to improve the healthcare system. For example, they may advise doctors about better ways to communicate with their patients. Health psychologists work in many different settings including the UK's National Health Service (NHS), private practice, universities, communities, schools and organizations. While many health psychologists provide clinical services as part of their duties, others function in non-clinical roles, primarily involving teaching and research. Leading journals include Health Psychology, the Journal of Health Psychology, the British Journal of Health Psychology, and Applied Psychology: Health and Well-Being. Health psychologists can work with people on a one-to-one basis, in groups, as a family, or at a larger population level.

Clinical health psychology (ClHP)

ClHP is the application of scientific knowledge, derived from the field of health psychology, to clinical questions that may arise across the spectrum of health care. ClHP is one of many specialty practice areas for clinical psychologists. It is also a major contributor to the prevention-focused field of behavioral health and the treatment-oriented field of behavioral medicine. Clinical practice includes education, the techniques of behavior change, and psychotherapy. In some countries, a clinical health psychologist, with additional training, can become a medical psychologist and, thereby, obtain prescription privileges.

Public health psychology (PHP)

PHP is population oriented. A major aim of PHP is to investigate potential causal links between psychosocial factors and health at the population level. Public health psychologists present research results to educators, policy makers, and health care providers in order to promote better public health. PHP is allied to other public health disciplines including epidemiology, nutrition, genetics and biostatistics. Some PHP interventions are targeted toward at-risk population groups (e.g., undereducated, single pregnant women who smoke) and not the population as a whole (e.g., all pregnant women).

Community health psychology (CoHP)

CoHP investigates community factors that contribute to the health and well-being of individuals who live in communities. CoHP also develops community-level interventions that are designed to combat disease and promote physical and mental health. The community often serves as the level of analysis, and is frequently sought as a partner in health-related interventions.

Critical health psychology (CrHP)

CrHP is concerned with the distribution of power and the impact of power differentials on health experience and behavior, health care systems, and health policy. CrHP prioritizes social justice and the universal right to health for people of all races, genders, ages, and socioeconomic positions. A major concern is health inequalities. The critical health psychologist is an agent of change, not simply an analyst or cataloger. A leading organization in this area is the International Society of Critical Health Psychology.

Health psychology, like other areas of applied psychology, is both a theoretical and applied field. Health psychologists employ diverse research methods. These methods include controlled randomized experiments, quasi-experiments, longitudinal studies, time-series designs, cross-sectional studies, case-control studies, qualitative research as well as action research. Health psychologists study a broad range of variables including cardiovascular disease, (cardiac psychology), smoking habits, the relation of religious beliefs to health, alcohol use, social support, living conditions, emotional state, social class, and more. Some health psychologists treat individuals with sleep problems, headaches, alcohol problems, etc. Other health psychologists work to empower community members by helping community members gain control over their health and improve quality of life of entire communities.

Origins and development

Psychological factors in health had been studied since the early 20th century by disciplines such as psychosomatic medicine and later behavioral medicine, but these were primarily branches of medicine, not psychology. Health psychology began to emerge as a distinct discipline of psychology in the United States in the 1970s. In the mid-20th century there was a growing understanding in medicine of the effect of behavior on health. For example, the Alameda County Study, which began in the 1960s, showed that people who ate regular meals (e.g., breakfast), maintained a healthy weight, received adequate sleep, did not smoke, drank little alcohol, and exercised regularly were in better health and lived longer. In addition, psychologists and other scientists were discovering relationships between psychological processes and physiological ones. These discoveries include a better understanding of the impact of psychosocial stress on the cardiovascular and immune systems, and the early finding that the functioning of the immune system could be altered by learning.

Psychologists have been working in medical settings for many years (in the UK sometimes the field was termed medical psychology). Medical psychology, however, was a relatively small field, primarily aimed at helping patients adjust to illness. In 1969, William Schofield prepared a report for the APA entitled The Role of Psychology in the Delivery of Health Services. While there were exceptions, he found that the psychological research of the time frequently regarded mental health and physical health as separate, and devoted very little attention to psychology's impact upon physical health. One of the few psychologists working in this area at the time, Schofield proposed new forms of education and training for future psychologists. The APA, responding to his proposal, in 1973 established a task force to consider how psychologists could (a) help people to manage their health-related behaviors, (b) help patients manage their physical health problems, and (c) train healthcare staff to work more effectively with patients.

Led by Joseph Matarazzo, in 1977, APA added a division devoted to health psychology. At the first divisional conference, Matarazzo delivered a speech that played an important role in defining health psychology. He defined the new field in this way, "Health psychology is the aggregate of the specific educational, scientific and professional contributions of the discipline of psychology to the promotion and maintenance of health, the prevention and treatment of illness, the identification of diagnostic and etiologic correlates of health, illness and related dysfunction, and the analysis and improvement of the healthcare system and health policy formation." In the 1980s, similar organizations were established elsewhere. In 1986, the BPS established a Division of Health Psychology. The European Health Psychology Society was also established in 1986. Similar organizations were established in other countries, including Australia and Japan. Universities began to develop doctoral level training programs in health psychology. In the US, post-doctoral level health psychology training programs were established for individuals who completed a doctoral degree in clinical psychology.
A number of relevant trends coincided with the emergence of health psychology, including:

• Epidemiological evidence linking behavior and health.
• The addition of behavioral science to medical school curricula, with courses often taught by psychologists.
• The training of health professionals in communication skills, with the aim of improving patient satisfaction and adherence to medical treatment.
• Increasing numbers of interventions based on psychological theory (e.g., behavior modification).
• An increased understanding of the interaction between psychological and physiological factors leading to the emergence of psychophysiology and psychoneuroimmunology (PNI).
• The health domain having become a target of research by social psychologists interested in testing theoretical models linking beliefs, attitudes, and behavior.
• The emergence of AIDS/HIV, and the increase in funding for behavioral research the epidemic provoked.

In the UK, the BPS’s reconsideration of the role of the Medical Section prompted the emergence of health psychology as a distinct field. Marie Johnston and John Weinman argued in a letter to the BPS Bulletin that there was a great need for a Health Psychology Section. In December 1986 the section was established at the BPS London Conference, with Marie Johnston as chair. At the Annual BPS Conference in 1993 a review of "Current Trends in Health Psychology" was organized, and a definition of health psychology as "the study of psychological and behavioural processes in health, illness and healthcare" was proposed. The Health Psychology Section became a Special Group in 1993 and was awarded divisional status within the UK in 1997. The awarding of divisional status meant that the individual training needs and professional practice of health psychologists were recognized, and members were able to obtain chartered status with the BPS. The BPS went on to regulate training and practice in health psychology until the regulation of professional standards and qualifications was taken over by statutory registration with the Health Professions Council in 2010.

Objectives

Understanding behavioral and contextual factors

Health psychologists conduct research to identify behaviors and experiences that promote health, give rise to illness, and influence the effectiveness of health care. They also recommend ways to improve health care policy. Health psychologists have worked on developing ways to reduce smoking and improve daily nutrition in order to promote health and prevent illness. They have also studied the association between illness and individual characteristics. For example, health psychology has found a relation between the personality characteristics of thrill seeking, impulsiveness, hostility/anger, emotional instability, and depression, on one hand, and high-risk driving, on the other.

Health psychology is also concerned with contextual factors, including economic, cultural, community, social, and lifestyle factors that influence health. The biopsychosocial model can help in understanding the relation between contextual factors and biology in affecting health. Physical addiction impedes smoking cessation. Some research suggests that seductive advertising also contributes to psychological dependency on tobacco, although other research has found no relationship between media exposure and smoking in youth. OHP research indicates that people in jobs that combine little decision latitude with a high psychological workload are at increased risk for cardiovascular disease. Other OHP research reveals a relation between unemployment and elevations in blood pressure. Epidemiologic research documents a relation between social class and cardiovascular disease.

Health psychologists also aim to change health behaviors for the dual purpose of helping people stay healthy and helping patients adhere to disease treatment regimens. Health psychologists employ cognitive behavior therapy and applied behavior analysis for that purpose.

Preventing illness

Health psychologists promote health through behavioral change, as mentioned above; however, they attempt to prevent illness in other ways as well. Health psychologists try to help people to lead a healthy life by developing and running programmes which can help people to make changes in their lives such as stopping smoking, reducing the amount of alcohol they consume, eating more healthily, and exercising regularly. Campaigns informed by health psychology have targeted tobacco use. Those least able to afford tobacco products consume them most. Tobacco provides individuals with a way of controlling aversive emotional states accompanying daily experiences of stress that characterize the lives of deprived and vulnerable individuals. Practitioners emphasize education and effective communication as a part of illness prevention because many people do not recognize, or minimize, the risk of illness present in their lives. Moreover, many individuals are often unable to apply their knowledge of health practices owing to everyday pressures and stresses. A common example of population-based attempts to motivate the smoking public to reduce its dependence on cigarettes is anti-smoking campaigns.

Health psychologists help to promote health and well-being by preventing illness. Some illnesses can be more effectively treated if caught early. Health psychologists have worked to understand why some people do not seek early screenings or immunizations, and have used that knowledge to develop ways to encourage people to have early health checks for illnesses such as cancer and heart disease. Health psychologists are also finding ways to help people to avoid risky behaviors (e.g., engaging in unprotected sex) and encourage health-enhancing behaviors (e.g., regular tooth brushing or hand washing).

Health psychologists also aim at educating health professionals, including physicians and nurses, in communicating effectively with patients in ways that overcome barriers to understanding, remembering, and implementing effective strategies for reducing exposures to risk factors and making health-enhancing behavior changes.

There is also evidence from OHP that stress-reduction interventions at the workplace can be effective. For example, Kompier and his colleagues have shown that a number of interventions aimed at reducing stress in bus drivers has had beneficial effects for employees and bus companies.

The effects of disease

Health psychologists investigate how disease affects individuals' psychological well-being. An individual who becomes seriously ill or injured faces many different practical stressors. These stressors include problems meeting medical and other bills, problems obtaining proper care when home from the hospital, obstacles to caring for dependents, the experience of having one's sense of self-reliance compromised, gaining a new, unwanted identity as that of a sick person, and so on. These stressors can lead to depression, reduced self-esteem, etc.

Health psychology also concerns itself with bettering the lives of individuals with terminal illness. When there is little hope of recovery, health psychologist therapists can improve the quality of life of the patient by helping the patient recover at least some of his or her psychological well-being. Health psychologists are also concerned with providing therapeutic services for the bereaved.

Critical analysis of health policy

Critical health psychologists explore how health policy can influence inequities, inequalities and social injustice. These avenues of research expand the scope of health psychology beyond the level of individual health to an examination of the social and economic determinants of health both within and between regions and nations. The individualism of mainstream health psychology has been critiqued and deconstructed by critical health psychologists using qualitative methods that zero in on the health experience.

Conducting research

Like psychologists in the other main psychology disciplines, health psychologists have advanced knowledge of research methods. Health psychologists apply this knowledge to conduct research on a variety of questions. For example, health psychologists carry out research to answer questions such as:

• What influences healthy eating?
• How is stress linked to heart disease?
• What are the emotional effects of genetic testing?
• How can we change people’s health behavior to improve their health?

Teaching and communication

Health psychologists can also be responsible for training other health professionals on how to deliver interventions to help promote healthy eating, stopping smoking, weight loss, etc. Health psychologists also train other health professionals in communication skills such as how to break bad news or support behavior change for the purpose of improving adherence to treatment.

Applications

Improving doctor–patient communication

Health psychologists aid the process of communication between physicians and patients during medical consultations. There are many problems in this process, with patients showing a considerable lack of understanding of many medical terms, particularly anatomical terms (e.g., intestines). One area of research on this topic involves "doctor-centered" or "patient-centered" consultations. Doctor-centered consultations are generally directive, with the patient answering questions and playing less of a role in decision-making. Although this style is preferred by elderly people and others, many people dislike the sense of hierarchy or ignorance that it inspires. They prefer patient-centered consultations, which focus on the patient's needs, involve the doctor listening to the patient completely before making a decision, and involving the patient in the process of choosing treatment and finding a diagnosis.

Improving adherence to medical advice

Health psychologists engage in research and practice aimed at getting people to follow medical advice and adhere to their treatment regimens. Patients often forget to take their pills or consciously opt not to take their prescribed medications because of side effects. Failing to take prescribed medication is costly and wastes millions of usable medicines that could otherwise help other people. Estimated adherence rates are difficult to measure (see below); there is, however, evidence that adherence could be improved by tailoring treatment programs to individuals' daily lives. Additionally, traditional cognitive-behavioural therapies have been adapted for people suffering from chronic illnesses and comorbid psychological distress to include modules that encourage, support and reinforce adherence to medical advice as part of the larger treatment approach.

Ways of measuring adherence

Health psychologists have identified a number of ways of measuring patients' adherence to medical regimens:

• Counting the number of pills in the medicine bottle
• Using self-reports
• Using "Trackcap" bottles, which track the number of times the bottle is opened.

Managing pain

Health psychology attempts to find treatments to reduce or eliminate pain, as well as understand pain anomalies such as episodic analgesia, causalgia, neuralgia, and phantom limb pain. Although the task of measuring and describing pain has been problematic, the development of the McGill Pain Questionnaire has helped make progress in this area. Treatments for pain involve patient-administered analgesia, acupuncture (found to be effective in reducing pain for osteoarthritis of the knee), biofeedback, and cognitive behavior therapy.

Health psychologist roles

Below are some examples of the types of positions held by health psychologists within applied settings such as the UK's NHS and private practice.

• Consultant health psychologist: A consultant health psychologist will take a lead for health psychology within public health, including managing tobacco control and smoking cessation services and providing professional leadership in the management of health trainers.
• Principal health psychologist: A principal health psychologist could, for example lead the health psychology service within one of the UK’s leading heart and lung hospitals, providing a clinical service to patients and advising all members of the multidisciplinary team.
• Health psychologist: An example of a health psychologist's role would be to provide health psychology input to a center for weight management. Psychological assessment of treatment, development and delivery of a tailored weight management program, and advising on approaches to improve adherence to health advice and medical treatment.
• Research psychologist: Research health psychologists carry out health psychology research, for example, exploring the psychological impact of receiving a diagnosis of dementia, or evaluating ways of providing psychological support for people with burn injuries. Research can also be in the area of health promotion, for example investigating the determinants of healthy eating or physical activity or understanding why people misuse substances.
• Health psychologist in training/assistant health psychologist: As an assistant/in training, a health psychologist will gain experience assessing patients, delivering psychological interventions to change health behaviors, and conducting research, whilst being supervised by a qualified health psychologist.

Training

In the UK, health psychologists are registered by the Health Professions Council (HPC) and have trained to a level to be eligible for full membership of the Division of Health Psychology within the BPS. Registered health psychologists who are chartered with the BPS will have undertaken a minimum of six years of training and will have specialized in health psychology for a minimum of three years. Health psychologists in training must have completed BPS stage 1 training and be registered with the BPS Stage 2 training route or with a BPS-accredited university doctoral health psychology program. Once qualified, health psychologists can work in a range of settings, for example the NHS, universities, schools, private healthcare, and research and charitable organizations. A health psychologist in training might be working within applied settings while working towards registration and chartered status. A health psychologist will have demonstrated competencies in all of the following areas:

• professional skills (including implementing ethical and legal standards, communication, and teamwork),
• research skills (including designing, conducting, and analyzing psychological research in numerous areas),
• consultancy skills (including planning and evaluation),
• teaching and training skills (including knowledge of designing, delivering, and evaluating large and small scale training program),
• intervention skills (including delivery and evaluation of behavior change interventions).

All qualified health psychologists must also engage in and record their continuing professional development (CPD) for psychology each year throughout their career.

Happiness

From Wikipedia, the free encyclopedia

Happiness is used in the context of mental or emotional states, including positive or pleasant emotions ranging from contentment to intense joy. It is also used in the context of life satisfaction, subjective well-being, eudaimonia, flourishing and well-being.

Since the 1960s, happiness research has been conducted in a wide variety of scientific disciplines, including gerontology, social psychology, clinical and medical research and happiness economics.

Definitions

'Happiness' is the subject of debate on usage and meaning, and on possible differences in understanding by culture.

The word is used in several related areas:

Happy children playing in water

• current experience, including (a) the feeling of an emotion (affect) such as pleasure or joy, or (b) a more general sense of 'emotional condition as a whole'. For instance Daniel Kahneman has defined happiness as "what I experience here and now". This usage is prevalent in dictionary definitions of happiness.
• appraisal of life satisfaction, such as of quality of life. For instance Ruut Veenhoven has defined happiness as "overall appreciation of one's life as-a-whole."
• subjective well-being, which includes measures of affect and of life satisfaction. For instance Sonja Lyubomirsky has described happiness as “the experience of joy, contentment, or positive well-being, combined with a sense that one's life is good, meaningful, and worthwhile.”
• eudaimonia, which is sometimes translated as flourishing.

These uses can give different results. For instance the correlation of income levels has been shown to be substantial with life satisfaction measures, but to be far weaker, at least above a certain threshold, with affect measures.

The implied meaning of the word may vary depending on context, qualifying happiness as a polyseme and a fuzzy concept.

Some users accept these issues, but continue to use the word because of it's convening power.

Philosophy

A smiling 95-year-old man from Pichilemu, Chile.

 

A butcher happily slicing meat.

In the Nicomachean Ethics, written in 350 BCE, Aristotle stated that happiness (also being well and doing well) is the only thing that humans desire for its own sake, unlike riches, honour, health or friendship. He observed that men sought riches, or honour, or health not only for their own sake but also in order to be happy. Note that eudaimonia, the term we translate as "happiness", is for Aristotle an activity rather than an emotion or a state. Thus understood, the happy life is the good life, that is, a life in which a person fulfills human nature in an excellent way. Specifically, Aristotle argues that the good life is the life of excellent rational activity. He arrives at this claim with the Function Argument. Basically, if it's right, every living thing has a function, that which it uniquely does. For humans, Aristotle contends, our function is to reason, since it is that alone that we uniquely do. And performing one's function well, or excellently, is good. Thus, according to Aristotle, the life of excellent rational activity is the happy life. Aristotle does not leave it at that, however. He argues that there is a second best life for those incapable of excellent rational activity. This second best life is the life of moral virtue.

Many ethicists make arguments for how humans should behave, either individually or collectively, based on the resulting happiness of such behavior. Utilitarians, such as John Stuart Mill and Jeremy Bentham, advocated the greatest happiness principle as a guide for ethical behavior.

Friedrich Nietzsche savagely critiqued the English Utilitarians' focus on attaining the greatest happiness, stating that "Man does not strive for happiness, only the Englishman does." Nietzsche meant that making happiness one's ultimate goal and the aim of one's existence, in his words "makes one contemptible." Nietzsche instead yearned for a culture that would set higher, more difficult goals than "mere happiness." He introduced the quasi-dystopic figure of the "last man" as a kind of thought experiment against the utilitarians and happiness-seekers. these small, "last men" who seek after only their own pleasure and health, avoiding all danger, exertion, difficulty, challenge, struggle are meant to seem contemptible to Nietzsche's reader. Nietzsche instead wants us to consider the value of what is difficult, what can only be earned through struggle, difficulty, pain and thus to come to see the affirmative value suffering and unhappiness truly play in creating everything of great worth in life, including all the highest achievements of human culture, not least of all philosophy.

Darrin McMahon claims that there has been a transition over time from emphasis on the happiness of virtue to the virtue of happiness.

Happiness may be said to be a relative concept; the source of happiness for one person might not be the source of happiness for another.

Not all cultures seek to maximise happiness, and some cultures are averse to happiness.

Religion

Eastern religions

Buddhism

Tibetan Buddhist monk

Happiness forms a central theme of Buddhist teachings. For ultimate freedom from suffering, the Noble Eightfold Path leads its practitioner to Nirvana, a state of everlasting peace. Ultimate happiness is only achieved by overcoming craving in all forms. More mundane forms of happiness, such as acquiring wealth and maintaining good friendships, are also recognized as worthy goals for lay people (see sukha). Buddhism also encourages the generation of loving kindness and compassion, the desire for the happiness and welfare of all beings.

Hinduism

In Advaita Vedanta, the ultimate goal of life is happiness, in the sense that duality between Atman and Brahman is transcended and one realizes oneself to be the Self in all.

Patanjali, author of the Yoga Sutras, wrote quite exhaustively on the psychological and ontological roots of bliss.

Confucianism

The Chinese Confucian thinker Mencius, who had sought to give advice to ruthless political leaders during China's Warring States period, was convinced that the mind played a mediating role between the "lesser self" (the physiological self) and the "greater self" (the moral self), and that getting the priorities right between these two would lead to sage-hood. He argued that if one did not feel satisfaction or pleasure in nourishing one's "vital force" with "righteous deeds", then that force would shrivel up (Mencius, 6A:15 2A:2). More specifically, he mentions the experience of intoxicating joy if one celebrates the practice of the great virtues, especially through music.

Abrahamic religions

Judaism

Happiness or simcha (Hebrew: שמחה‎) in Judaism is considered an important element in the service of God. The biblical verse "worship The Lord with gladness; come before him with joyful songs," (Psalm 100:2) stresses joy in the service of God. A popular teaching by Rabbi Nachman of Breslov, a 19th-century Chassidic Rabbi, is "Mitzvah Gedolah Le'hiyot Besimcha Tamid," it is a great mitzvah (commandment) to always be in a state of happiness. When a person is happy they are much more capable of serving God and going about their daily activities than when depressed or upset.

Roman Catholicism

The primary meaning of "happiness" in various European languages involves good fortune, chance or happening. The meaning in Greek philosophy, however, refers primarily to ethics.

In Catholicism, the ultimate end of human existence consists in felicity, Latin equivalent to the Greek eudaimonia, or "blessed happiness", described by the 13th-century philosopher-theologian Thomas Aquinas as a Beatific Vision of God's essence in the next life.

According to St. Augustine and Thomas Aquinas, man's last end is happiness: "all men agree in desiring the last end, which is happiness." However, where utilitarians focused on reasoning about consequences as the primary tool for reaching happiness, Aquinas agreed with Aristotle that happiness cannot be reached solely through reasoning about consequences of acts, but also requires a pursuit of good causes for acts, such as habits according to virtue. In turn, which habits and acts that normally lead to happiness is according to Aquinas caused by laws: natural law and divine law. These laws, in turn, were according to Aquinas caused by a first cause, or God.

According to Aquinas, happiness consists in an "operation of the speculative intellect": "Consequently happiness consists principally in such an operation, viz. in the contemplation of Divine things." And, "the last end cannot consist in the active life, which pertains to the practical intellect." So: "Therefore the last and perfect happiness, which we await in the life to come, consists entirely in contemplation. But imperfect happiness, such as can be had here, consists first and principally in contemplation, but secondarily, in an operation of the practical intellect directing human actions and passions."

Human complexities, like reason and cognition, can produce well-being or happiness, but such form is limited and transitory. In temporal life, the contemplation of God, the infinitely Beautiful, is the supreme delight of the will. Beatitudo, or perfect happiness, as complete well-being, is to be attained not in this life, but the next.

Islam

Al-Ghazali (1058–1111), the Muslim Sufi thinker, wrote "The Alchemy of Happiness", a manual of spiritual instruction throughout the Muslim world and widely practiced today.

Psychology

Happiness in its broad sense is the label for a family of pleasant emotional states, such as joy, amusement, satisfaction, gratification, euphoria, and triumph.

Happiness can be examined in experiential and evaluative contexts. Experiential well-being, or "objective happiness", is happiness measured in the moment via questions such as "How good or bad is your experience now?". In contrast, evaluative well-being asks questions such as "How good was your vacation?" and measures one's subjective thoughts and feelings about happiness in the past. Experiential well-being is less prone to errors in reconstructive memory, but the majority of literature on happiness refers to evaluative well-being. The two measures of happiness can be related by heuristics such as the peak-end rule.

Some commentators focus on the difference between the hedonistic tradition of seeking pleasant and avoiding unpleasant experiences, and the eudaimonic tradition of living life in a full and deeply satisfying way.

Theories on how to achieve happiness include "encountering unexpected positive events", "seeing a significant other", and "basking in the acceptance and praise of others". However others believe that happiness is not solely derived from external, momentary pleasures.

Theories

Maslow's hierarchy of needs

Maslow's hierarchy of needs is a pyramid depicting the levels of human needs, psychological, and physical. When a human being ascends the steps of the pyramid, he reaches self-actualization. Beyond the routine of needs fulfillment, Maslow envisioned moments of extraordinary experience, known as peak experiences, profound moments of love, understanding, happiness, or rapture, during which a person feels more whole, alive, self-sufficient, and yet a part of the world. This is similar to the flow concept of Mihály Csíkszentmihályi. Amitai Etzioni points out that Maslow's definition of human needs, even on the highest level, that of self-actualization, is self-centered (i.e. his view of satisfaction or what makes a person happy, does not include service to others or the common good—unless it enriches the self). As implied by its name, self-actualization is highly individualistic and reflects Maslow's premise that the self is “sovereign and inviolable” and entitled to “his or her own tastes, opinions, values, etc.”

Self-determination theory

Smiling woman from Vietnam

Self-determination theory relates intrinsic motivation to three needs: competence, autonomy, and relatedness.

Modernization and freedom of choice

Ronald Inglehart has traced cross-national differences in the level of happiness based on data from the World Values Survey. He finds that the extent to which a society allows free choice has a major impact on happiness. When basic needs are satisfied, the degree of happiness depends on economic and cultural factors that enable free choice in how people live their lives. Happiness also depends on religion in countries where free choice is constrained.

Positive psychology

Since 2000 the field of positive psychology has expanded drastically in terms of scientific publications, and has produced many different views on causes of happiness, and on factors that correlate with happiness. Numerous short-term self-help interventions have been developed and demonstrated to improve happiness.

Measurement of happiness

Several scales have been developed to measure happiness:

• The Subjective Happiness Scale (SHS) is a four-item scale, measuring global subjective happiness. The scale requires participants to use absolute ratings to characterize themselves as happy or unhappy individuals, as well as it asks to what extent they identify themselves with descriptions of happy and unhappy individuals.
• The Positive and Negative Affect Schedule (PANAS) is used to detect the relation between personality traits and positive or negative affects at this moment, today, the past few days, the past week, the past few weeks, the past year, and generally (on average). PANAS is a 20-item questionnaire, which uses a five-point Likert scale (1 = very slightly or not at all, 5 = extremely). A longer version with additional affect scales is available in a manual.
• The Satisfaction with Life Scale (SWLS) is a global cognitive assessment of life satisfaction developed by Ed Diener. The SWLS requires a person to use a seven-item scale to state their agreement or disagreement (1 = strongly disagree, 4 = neither agree nor disagree, 7 = strongly agree) with five statements about their life.

The UK began to measure national well being in 2012, following Bhutan, which already measured gross national happiness.

The 2012 World Happiness Report stated that in subjective well-being measures, the primary distinction is between cognitive life evaluations and emotional reports. Happiness is used in both life evaluation, as in “How happy are you with your life as a whole?”, and in emotional reports, as in “How happy are you now?,” and people seem able to use happiness as appropriate in these verbal contexts. Using these measures, the World Happiness Report identifies the countries with the highest levels of happiness.

Etzioni argues that happiness is the wrong metric, because it does not take into account that doing the right thing, what is moral, often does not produce happiness in the way this term is usually used.
Happiness has been found to be quite stable over time.

Relationship to physical characteristics

Even though no evidence of happiness causing improved physical health has been found, the topic is being researched by Laura Kubzansky, a professor at the Lee Kum Sheung Center for Health and Happiness at the Harvard T.H. Chan School of Public Health, Harvard University. A positive relationship has been suggested between the volume of gray matter in the right precuneus area of the brain and the subject's subjective happiness score.

Possible limits on happiness seeking

June Gruber suggests that seeking happiness can have negative effects, such as failure to meet over-high expectations, and instead advocates a more open stance to all emotions. Other research has analysed possible trade-offs between happiness and meaning in life. Not all cultures seek to maximise happiness.

Economic and political views

Newly commissioned officers celebrate their new positions by throwing their midshipmen covers into the air as part of the U.S. Naval Academy class of 2011 graduation and commissioning ceremony.

In politics, happiness as a guiding ideal is expressed in the United States Declaration of Independence of 1776, written by Thomas Jefferson, as the universal right to "the pursuit of happiness." This seems to suggest a subjective interpretation but one that nonetheless goes beyond emotions alone. In fact, this discussion is often based on the naive assumption that the word happiness meant the same thing in 1776 as it does today. In fact, happiness meant "prosperity, thriving, wellbeing" in the 18th century.

Common market health measures such as GDP and GNP have been used as a measure of successful policy. On average richer nations tend to be happier than poorer nations, but this effect seems to diminish with wealth. This has been explained by the fact that the dependency is not linear but logarithmic, i.e., the same percentual increase in the GNP produces the same increase in happiness for wealthy countries as for poor countries. Increasingly, academic economists and international economic organisations are arguing for and developing multi-dimensional dashboards which combine subjective and objective indicators to provide a more direct and explicit assessment of human wellbeing. Work by Paul Anand and colleagues helps to highlight the fact that there many different contributors to adult wellbeing, that happiness judgement reflect, in part, the presence of salient constraints, and that fairness, autonomy, community and engagement are key aspects of happiness and wellbeing throughout the life course.

Libertarian think tank Cato Institute claims that economic freedom correlates strongly with happiness preferably within the context of a western mixed economy, with free press and a democracy. According to certain standards, East European countries (ruled by Communist parties) were less happy than Western ones, even less happy than other equally poor countries.

However, much empirical research in the field of happiness economics, such as that by Benjamin Radcliff, professor of Political Science at the University of Notre Dame, supports the contention that (at least in democratic countries) life satisfaction is strongly and positively related to the social democratic model of a generous social safety net, pro-worker labor market regulations, and strong labor unions. Similarly, there is evidence that public policies that reduce poverty and support a strong middle class, such as a higher minimum wage, strongly affects average levels of well-being.

It has been argued that happiness measures could be used not as a replacement for more traditional measures, but as a supplement. According to professor Edward Glaeser, people constantly make choices that decrease their happiness, because they have also more important aims. Therefore, the government should not decrease the alternatives available for the citizen by patronizing them but let the citizen keep a maximal freedom of choice.

Good mental health and good relationships contribute more than income to happiness and governments should take these into account.

Contributing factors and research outcomes

Research on positive psychology, well-being, eudaimonia and happiness, and the theories of Diener, Ryff, Keyes, and Seligmann covers a broad range of levels and topics, including "the biological, personal, relational, institutional, cultural, and global dimensions of life."

Reward system

From Wikipedia, the free encyclopedia

Examples of primary rewards

Water Sex

Food Parental care

Addiction and dependence glossary

addiction – a brain disorder characterized by compulsive engagement in rewarding stimuli despite adverse consequences addictive behavior – a behavior that is both rewarding and reinforcing addictive drug – a drug that is both rewarding and reinforcing dependence – an adaptive state associated with a withdrawal syndrome upon cessation of repeated exposure to a stimulus (e.g., drug intake) drug sensitization or reverse tolerance – the escalating effect of a drug resulting from repeated administration at a given dose drug withdrawal – symptoms that occur upon cessation of repeated drug use physical dependence – dependence that involves persistent physical–somatic withdrawal symptoms (e.g., fatigue and delirium tremens) psychological dependence – dependence that involves emotional–motivational withdrawal symptoms (e.g., dysphoria and anhedonia) reinforcing stimuli – stimuli that increase the probability of repeating behaviors paired with them rewarding stimuli – stimuli that the brain interprets as intrinsically positive and desirable or as something to approach sensitization – an amplified response to a stimulus resulting from repeated exposure to it substance use disorder – a condition in which the use of substances leads to clinically and functionally significant impairment or distress tolerance – the diminishing effect of a drug resulting from repeated administration at a given dose

The reward system is a group of neural structures responsible for incentive salience (i.e., motivation and "wanting", desire, or craving for a reward), associative learning (primarily positive reinforcement and classical conditioning), and positively-valenced emotions, particularly ones which involve pleasure as a core component (e.g., joy, euphoria and ecstasy). Reward is the attractive and motivational property of a stimulus that induces appetitive behavior, also known as approach behavior, and consummatory behavior. In its description of a rewarding stimulus (i.e., "a reward"), a review on reward neuroscience noted, "any stimulus, object, event, activity, or situation that has the potential to make us approach and consume it is by definition a reward." In operant conditioning, rewarding stimuli function as positive reinforcers; however, the converse statement also holds true: positive reinforcers are rewarding.

Primary rewards are a class of rewarding stimuli which facilitate the survival of one's self and offspring, and include homeostatic (e.g., palatable food) and reproductive (e.g., sexual contact and parental investment) rewards. Intrinsic rewards are unconditioned rewards that are attractive and motivate behavior because they are inherently pleasurable. Extrinsic rewards (e.g., money or seeing one's favorite sports team winning a game) are conditioned rewards that are attractive and motivate behavior, but are not inherently pleasurable. Extrinsic rewards derive their motivational value as a result of a learned association (i.e., conditioning) with intrinsic rewards. Extrinsic rewards may also elicit pleasure (e.g., euphoria from winning a lot of money in a lottery) after being classically conditioned with intrinsic rewards.

Survival for most animal species depends upon maximizing contact with beneficial stimuli and minimizing contact with harmful stimuli. Reward cognition serves to increase the likelihood of survival and reproduction by causing associative learning, eliciting approach and consummatory behavior, and triggering positively-valenced emotions. Thus, reward is a mechanism that evolved to help increase the adaptive fitness of animals.

Definition

In neuroscience, the reward system is a collection of brain structures and neural pathways that are responsible for reward-related cognition, including associative learning (primarily classical conditioning and operant reinforcement), incentive salience (i.e., motivation and "wanting", desire, or craving for a reward), and positively-valenced emotions, particularly emotions that involve pleasure (i.e., hedonic "liking").

Terms that are commonly used to describe behavior related to the "wanting" or desire component of reward include appetitive behavior, approach behavior, preparatory behavior, instrumental behavior, anticipatory behavior, and seeking. Terms that are commonly used to describe behavior related to the "liking" or pleasure component of reward include consummatory behavior and taking behavior.

The three primary functions of rewards are their capacity to:

1. produce associative learning (i.e., classical conditioning and operant reinforcement);
2. affect decision-making and induce approach behavior (via the assignment of motivational salience to rewarding stimuli);
3. elicit positively-valenced emotions, particularly pleasure.

Anatomy

The brain structures that compose the reward system are located primarily within the cortico-basal ganglia-thalamo-cortical loop; the basal ganglia portion of the loop drives activity within the reward system. Most of the pathways that connect structures within the reward system are glutamatergic interneurons, GABAergic medium spiny neurons (MSNs), and dopaminergic projection neurons, although other types of projection neurons contribute (e.g., orexinergic projection neurons). The reward system includes the ventral tegmental area, ventral striatum (i.e., the nucleus accumbens and olfactory tubercle), dorsal striatum (i.e., the caudate nucleus and putamen), substantia nigra (i.e., the pars compacta and pars reticulata), prefrontal cortex, anterior cingulate cortex, insular cortex, hippocampus, hypothalamus (particularly, the orexinergic nucleus in the lateral hypothalamus), thalamus (multiple nuclei), subthalamic nucleus, globus pallidus (both external and internal), ventral pallidum, parabrachial nucleus, amygdala, and the remainder of the extended amygdala. The dorsal raphe nucleus and cerebellum appear to modulate some forms of reward-related cognition (i.e., associative learning, motivational salience, and positive emotions) and behaviors as well. The laterodorsal tegmental nucleus (LTD), pedunculopontine nucleus (PPTg), and lateral habenula (LHb) (both directly and indirectly via the rostromedial tegmental nucleus) are also capable of inducing aversive salience and incentive salience through their projections to the ventral tegmental area (VTA). The LDT and PPTg both send glutaminergic projections to the VTA that synapse on dopaminergic neurons, both of which can produce incentive salience. The LHb sends glutaminergic projections, the majority of which synapse on GABAergic RMTg neurons that in turn drive inhibition of dopaminergic VTA neurons, although some LHb projections terminate on VTA interneurons. These LHb projections are activated both by aversive stimuli and by the absence of an expected reward, and excitation of the LHb can induce aversion.

Most of the dopamine pathways (i.e., neurons that use the neurotransmitter dopamine to communicate with other neurons) that project out of the ventral tegmental area are part of the reward system; in these pathways, dopamine acts on D1-like receptors or D2-like receptors to either stimulate (D1-like) or inhibit (D2-like) the production of cAMP. The GABAergic medium spiny neurons of the striatum are components of the reward system as well. The glutamatergic projection nuclei in the subthalamic nucleus, prefrontal cortex, hippocampus, thalamus, and amygdala connect to other parts of the reward system via glutamate pathways. The medial forebrain bundle, which is a set of many neural pathways that mediate brain stimulation reward (i.e., reward derived from direct electrochemical stimulation of the lateral hypothalamus), is also a component of the reward system.

Two theories exist with regard to the activity of the nucleus accumbens and the generation liking and wanting. The inhibition (or hyper­polar­ization) hypothesis proposes that the nucleus accumbens exerts tonic inhibitory effects on downstream structures such as the ventral pallidum, hypothalamus or ventral tegmental area, and that in inhibiting MSNs in the nucleus accumbens (NAcc), these structures are excited, "releasing" reward related behavior. While GABA receptor agonists are capable of eliciting both "liking" and "wanting" reactions in the nucleus accumbens, glutaminergic inputs from the basolateral amygdala, ventral hippocampus, and medial prefrontal cortex can drive incentive salience. Furthermore, while most studies find that NAcc neurons reduce firing in response to reward, a number of studies find the opposite response. This had led to the proposal of the disinhibition (or depolarization) hypothesis, that proposes that excitation or NAcc neurons, or at least certain subsets, drives reward related behavior.

After nearly 50 years of research on brain-stimulation reward, experts have certified that dozens of sites in the brain will maintain intracranial self-stimulation. Regions include the lateral hypothalamus and medial forebrain bundles, which are especially effective. Stimulation there activates fibers that form the ascending pathways; the ascending pathways include the mesolimbic dopamine pathway, which projects from the ventral tegmental area to the nucleus accumbens. There are several explanations as to why the mesolimbic dopamine pathway is central to circuits mediating reward. First, there is a marked increase in dopamine release from the mesolimbic pathway when animals engage in intracranial self-stimulation. Second, experiments consistently indicate that brain-stimulation reward stimulates the reinforcement of pathways that are normally activated by natural rewards, and drug reward or intracranial self-stimulation can exert more powerful activation of central reward mechanisms because they activate the reward center directly rather than through the peripheral nerves. Third, when animals are administered addictive drugs or engage in naturally rewarding behaviors, such as feeding or sexual activity, there is a marked release of dopamine within the nucleus accumbens. However, dopamine is not the only reward compound in the brain.

Pleasure centers

Pleasure is a component of reward, but not all rewards are pleasurable (e.g., money does not elicit pleasure unless this response is conditioned). Stimuli that are naturally pleasurable, and therefore attractive, are known as intrinsic rewards, whereas stimuli that are attractive and motivate approach behavior, but are not inherently pleasurable, are termed extrinsic rewards. Extrinsic rewards (e.g., money) are rewarding as a result of a learned association with an intrinsic reward. In other words, extrinsic rewards function as motivational magnets that elicit "wanting", but not "liking" reactions once they have been acquired.

The reward system contains pleasure centers or hedonic hotspots – i.e., brain structures that mediate pleasure or "liking" reactions from intrinsic rewards. As of October 2017, hedonic hotspots have been identified in subcompartments within the nucleus accumbens shell, ventral pallidum, parabrachial nucleus, orbitofrontal cortex (OFC), and insular cortex. The hotspot within the nucleus accumbens shell is located in the rostrodorsal quadrant of the medial shell, while the hedonic coldspot is located in a more posterior region. The posterior ventral pallidum also contains a hedonic hotspot, while the anterior ventral pallidum contains a hedonic coldspot. Microinjections of opioids, endocannabinoids, and orexin are capable of enhancing liking in these hotspots. The hedonic hotspots located in the anterior OFC and posterior insula have been demonstrated to respond to orexin and opioids, as has the overlapping hedonic coldspot in the anterior insula and posterior OFC. On the other hand, the parabrachial nucleus hotspot has only been demonstrated to respond to benzodiazepine receptor agonists.

Hedonic hotspots are functionally linked, in that activation of one hotspot results in the recruitment of the others, as indexed by the induced expression of c-Fos, an immediate early gene. Furthermore, inhibition of one hotspot results in the blunting of the effects of activating another hotspot. Therefore, the simultaneous activation of every hedonic hotspot within the reward system is believed to be necessary for generating the sensation of an intense euphoria.

Wanting

Tuning of appetitive and defensive reactions in the nucleus accumbens shell. (Above) AMPA blockade requires D1 function in order to produce motivated behaviors, regardless of valence, and D2 function to produce defensive behaviors. GABA agonism, on the other hand, does not requires dopamine receptor function.(Below)The expansion of the anatomical regions that produce defensive behaviors under stress, and appetitive behaviors in the home environment produced by AMPA antagonism. This flexibility is less evident with GABA agonism.

 

Incentive salience is the "wanting" or "desire" attribute, which includes a motivational component, that is assigned to a rewarding stimulus by the nucleus accumbens shell (NAcc shell). The degree of dopamine neurotransmission into the NAcc shell from the mesolimbic pathway is highly correlated with the magnitude of incentive salience for rewarding stimuli.

Activation of the dorsorostral region of the nucleus accumbens correlates with increases in wanting without concurrent increases in liking. However, dopaminergic neurotransmission into the nucleus accumbens shell is responsible not only for appetitive motivational salience (i.e., incentive salience) towards rewarding stimuli, but also for aversive motivational salience, which directs behavior away from undesirable stimuli. In the dorsal striatum, activation of D1 expressing MSNs produces appetitive incentive salience, while activation of D2 expressing MSNs produces aversion. In the NAcc, such a dichotomy is not as clear cut, and activation of both D1 and D2 MSNs is sufficient to enhance motivation, likely via disinhibiting the VTA through inhibiting the ventral pallidum.

Robinson and Berridge's incentive-sensitization theory (1993) proposed that reward contains separable psychological components: wanting (incentive) and liking (pleasure). To explain increasing contact with a certain stimulus such as chocolate, there are two independent factors at work – our desire to have the chocolate (wanting) and the pleasure effect of the chocolate (liking). According to Robinson and Berridge, wanting and liking are two aspects of the same process, so rewards are usually wanted and liked to the same degree. However, wanting and liking also change independently under certain circumstances. For example, rats that do not eat after receiving dopamine (experiencing a loss of desire for food) act as though they still like food. In another example, activated self-stimulation electrodes in the lateral hypothalamus of rats increase appetite, but also cause more adverse reactions to tastes such as sugar and salt; apparently, the stimulation increases wanting but not liking. Such results demonstrate that our reward system includes independent processes of wanting and liking. The wanting component is thought to be controlled by dopaminergic pathways, whereas the liking component is thought to be controlled by opiate-benzodiazepine systems.

Animals vs. humans

Animals quickly learn to press a bar to obtain an injection of opiates directly into the midbrain tegmentum or the nucleus accumbens. The same animals do not work to obtain the opiates if the dopaminergic neurons of the mesolimbic pathway are inactivated. In this perspective, animals, like humans, engage in behaviors that increase dopamine release.

Kent Berridge, a researcher in affective neuroscience, found that sweet (liked ) and bitter (disliked ) tastes produced distinct orofacial expressions, and these expressions were similarly displayed by human newborns, orangutans, and rats. This was evidence that pleasure (specifically, liking) has objective features and was essentially the same across various animal species. Most neuroscience studies have shown that the more dopamine released by the reward, the more effective the reward is. This is called the hedonic impact, which can be changed by the effort for the reward and the reward itself. Berridge discovered that blocking dopamine systems did not seem to change the positive reaction to something sweet (as measured by facial expression). In other words, the hedonic impact did not change based on the amount of sugar. This discounted the conventional assumption that dopamine mediates pleasure. Even with more-intense dopamine alterations, the data seemed to remain constant.

Berridge developed the incentive salience hypothesis to address the wanting aspect of rewards. It explains the compulsive use of drugs by drug addicts even when the drug no longer produces euphoria, and the cravings experienced even after the individual has finished going through withdrawal. Some addicts respond to certain stimuli involving neural changes caused by drugs. This sensitization in the brain is similar to the effect of dopamine because wanting and liking reactions occur. Human and animal brains and behaviors experience similar changes regarding reward systems because these systems are so prominent.

Learning

Rewarding stimuli can drive learning in both the form of classical conditioning (Pavlovian conditioning) and operant conditioning (instrumental conditioning). In classical conditioning, a reward can act as an unconditioned stimulus that, when associated with the conditioned stimulus, causes the conditioned stimulus to elicit both musculoskeletal (in the form of simple approach and avoidance behaviors) and vegetative responses. In operant conditioning, a reward may act as a reinforcer in that it increases or supports actions that lead to itself. Learned behaviors may or may not be sensitive to the value of the outcomes they lead to; behaviors that are sensitive to the contingency of an outcome on the performance of an action as well as the outcome value are goal-directed, while elicited actions that are insensitive to contingency or value are called habits. This distinction is thought to reflected two forms of learning, model free and model based. Model free learning involves the simple caching and updating of values. In contrast, model based learning involves the storage and construction of an internal model of events that allows inference and flexible prediction. Although pavlovian conditioning is generally assumed to be model-free, the incentive salience assigned to a conditioned stimulus is flexible with regard to changes in internal motivational states.

Distinct neural systems are responsible for learning associations between stimuli and outcomes, actions and outcomes, and stimuli and responses. Although classical conditioning is not limited to the reward system, the enhancement of instrumental performance by stimuli (i.e., Pavlovian-instrumental transfer) requires the nucleus accumbens. Habitual and goal directed instrumental learning are dependent upon the lateral striatum and the medial striatum, respectively.

During instrumental learning, opposing changes in the ratio of AMPA to NMDA receptors and phosphorylated ERK occurs in the D₁-type and D₂-type MSNs that constitute the direct and indirect pathways, respectively. These changes in synaptic plasticity and the accompanying learning is dependent upon activation of striatal D1 and NMDA receptors. The intracellular cascade activated by D1 receptors involves the recruitment of protein kinase A, and through resulting phosphorylation of DARPP-32, the inhibition of phosphatases that deactivate ERK. NMDA receptors activate ERK through a different but interrelated Ras-Raf-MEK-ERK pathway. Alone NMDA mediated activation of ERK is self-limited, as NMDA activation also inhibits PKA mediated inhibition of ERK deactivating phosphatases. However, when D1 and NMDA cascades are co-activated, they work synergistically, and the resultant activation of ERK regulates synaptic plasticity in the form of spine restructuring, transport of AMPA receptors, regulation of CREB, and increasing cellular excitability via inhibiting Kv4.2.

History

Skinner box

The first clue to the presence of a reward system in the brain came with an accident discovery by James Olds and Peter Milner in 1954. They discovered that rats would perform behaviors such as pressing a bar, to administer a brief burst of electrical stimulation to specific sites in their brains. This phenomenon is called intracranial self-stimulation or brain stimulation reward. Typically, rats will press a lever hundreds or thousands of times per hour to obtain this brain stimulation, stopping only when they are exhausted. While trying to teach rats how to solve problems and run mazes, stimulation of certain regions of the brain where the stimulation was found seemed to give pleasure to the animals. They tried the same thing with humans and the results were similar. The explanation to why animals engage in a behavior that has no value to the survival of either themselves or their species is that the brain stimulation is activating the system underlying reward.

In a fundamental discovery made in 1954, researchers James Olds and Peter Milner found that low-voltage electrical stimulation of certain regions of the brain of the rat acted as a reward in teaching the animals to run mazes and solve problems. It seemed that stimulation of those parts of the brain gave the animals pleasure, and in later work humans reported pleasurable sensations from such stimulation. When rats were tested in Skinner boxes where they could stimulate the reward system by pressing a lever, the rats pressed for hours. Research in the next two decades established that dopamine is one of the main chemicals aiding neural signaling in these regions, and dopamine was suggested to be the brain's "pleasure chemical".

Ivan Pavlov was a psychologist who used the reward system to study classical conditioning. Pavlov used the reward system by rewarding dogs with food after they had heard a bell or another stimulus. Pavlov was rewarding the dogs so that the dogs associated food, the reward, with the bell, the stimulus. Edward L. Thorndike used the reward system to study operant conditioning. He began by putting cats in a puzzle box and placing food outside of the box so that the cat wanted to escape. The cats worked to get out of the puzzle box to get to the food. Although the cats ate the food after they escaped the box, Thorndike learned that the cats attempted to escape the box without the reward of food. Thorndike used the rewards of food and freedom to stimulate the reward system of the cats. Thorndike used this to see how the cats learned to escape the box.

Clinical significance

Addiction

ΔFosB (DeltaFosB) – a gene transcription factor – overexpression in the D1-type medium spiny neurons of the nucleus accumbens is the crucial common factor among virtually all forms of addiction (i.e., behavioral addictions and drug addictions) that induces addiction-related behavior and neural plasticity. In particular, ΔFosB promotes self-administration, reward sensitization, and reward cross-sensitization effects among specific addictive drugs and behaviors. Certain epigenetic modifications of histone protein tails (i.e., histone modifications) in specific regions of the brain are also known to play a crucial role in the molecular basis of addictions.

Addictive drugs and behaviors are rewarding and reinforcing (i.e., are addictive) due to their effects on the dopamine reward pathway.

The lateral hypothalamus and medial forebrain bundle has been the most-frequently-studied brain-stimulation reward site, particularly in studies of the effects of drugs on brain stimulation reward.^[64] The neurotransmitter system that has been most-clearly identified with the habit-forming actions of drugs-of-abuse is the mesolimbic dopamine system, with its efferent targets in the nucleus accumbens and its local GABAergic afferents. The reward-relevant actions of amphetamine and cocaine are in the dopaminergic synapses of the nucleus accumbens and perhaps the medial prefrontal cortex. Rats also learn to lever-press for cocaine injections into the medial prefrontal cortex, which works by increasing dopamine turnover in the nucleus accumbens. Nicotine infused directly into the nucleus accumbens also enhances local dopamine release, presumably by a presynaptic action on the dopaminergic terminals of this region. Nicotinic receptors localize to dopaminergic cell bodies and local nicotine injections increase dopaminergic cell firing that is critical for nicotinic reward. Some additional habit-forming drugs are also likely to decrease the output of medium spiny neurons as a consequence, despite activating dopaminergic projections. For opiates, the lowest-threshold site for reward effects involves actions on GABAergic neurons in the ventral tegmental area, a secondary site of opiate-rewarding actions on medium spiny output neurons of the nucleus accumbens. Thus GABAergic afferents to the mesolimbic dopamine neurons (primary substrate of opiate reward), the mesolimbic dopamine neurons themselves (primary substrate of psychomotor stimulant reward), and GABAergic efferents to the mesolimbic dopamine neurons (a secondary site of opiate reward) form the core of currently characterized drug-reward circuitry.

Motivation

Dysfunctional motivational salience appears in a number of psychiatric symptoms and disorders. Anhedonia, traditionally defined as a reduced capacity to feel pleasure, has been reexamined as reflecting blunted incentive salience, as most anhedonic populations exhibit intact “liking”. On the other end of the spectrum, heightened incentive salience that is narrowed for specific stimuli is characteristic of behavioral and drug addictions. In the case of fear or paranoia, dysfunction may lie in elevated aversive salience.

Neuroimaging studies across diagnoses associated with anhedonia have reported reduced activity in the OFC and ventral striatum. One meta analysis reported anhedonia was associated with reduced neural response to reward anticipation in the caudate nucleus, putamen, nucleus accumbens and medial prefrontal cortex (mPFC).

Mood Disorders

Depression is associated with reduced motivation, as assessed by willingness to expend effort for reward. These abnormalities have been tentatively linked to reduced activity in areas of the striatum, and while dopaminergic abnormalities are hypothesized to play a role, most studies probing dopamine function in depression have reported inconsistent results. Although postmortem and neuroimaging studies have found abnormalities in numerous regions of the reward system, few findings are consistently replicated. Some studies have reported reduced NAcc, hippocampus, medial prefrontal cortex (mPFC), and orbitofrontal cortex (OFC) activity, as well as elevated basolateral amygdala and subgenual cingulate cortex (sgACC) activity during tasks related to reward or positive stimuli. These neuroimaging abnormalities are complimented by little post mortem research, but what little research has been done suggests reduced excitatory synapses in the mPFC. Reduced activity in the mPFC during reward related tasks appears to be localized to more dorsal regions(i.e. the pregenual cingulate cortex), while the more ventral sgACC is hyperactive in depression.

Attempts to investigate underlying neural circuitry in animal models has also yielded conflicting results. Two paradigms are commonly used to simulate depression, chronic social defeat (CSDS), and chronic mild stress (CMS), although many exist. CSDS produces reduced preference for sucrose, reduced social interactions, and increased immobility in the forced swim test. CMS similarly reduces sucrose preference, and behavioral despair as assessed by tail suspension and forced swim tests. Animals susceptible to CSDS exhibit increased phasic VTA firing, and inhibition of VTA-NAcc projections attenuates behavioral deficits induced by CSDS. However, inhibition of VTA-mPFC projections exacerbates social withdrawal. On the other hand, CMS associated reductions in sucrose preference and immobility were attenuated and exacerbated by VTA excitation and inhibition, respectively. Although these differences may be attributable to different stimulation protocols or poor translational paradigms, variable results may also lie in the heterogenous functionality of reward related regions.

Optogenetic stimulation of the mPFC as a whole produces antidepressant effects. This effect appears localized to the rodent homologue of the pgACC (the prelimbic cortex), as stimulation of the rodent homologue of the sgACC (the infralimbic cortex) produces no behavioral effects. Furthermore, deep brain stimulation in the infralimbic cortex, which is thought to have an inhibitory effect, also produces an antidepressant effect. This finding is congruent with the observation that pharmacological inhibition of the infralimbic cortex attenuates depressive behaviors.

Schizophrenia

Schizophrenia is associated with deficits in motivation, commonly grouped under other negative symptoms such as reduced spontaneous speech. The experience of “liking” is frequently reported to be intact, both behaviorally and neurally, although results may be specific to certain stimuli, such as monetary rewards. Furthermore, implicit learning and simple reward related tasks are also intact in schizophrenia. Rather, deficits in the reward system present during reward related tasks that are cognitively complex. These deficits are associated with both abnormal striatal and OFC activity, as well as abnormalities in regions associated with cognitive functions such as the dorsolateral prefrontal cortex (dlPFC).