Dopamine hypothesis of schizophrenia

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Dopamine_hypothesis_of_schizophrenia 

 

The dopamine hypothesis of schizophrenia or the dopamine hypothesis of psychosis is a model that attributes the positive symptoms of schizophrenia to a disturbed and hyperactive dopaminergic signal transduction. The model draws evidence from the observation that a large number of antipsychotics have dopamine-receptor antagonistic effects. The theory, however, does not posit dopamine overabundance as a complete explanation for schizophrenia. Rather, the overactivation of D2 receptors, specifically, is one effect of the global chemical synaptic dysregulation observed in this disorder.

Introduction

Some researchers have suggested that dopamine systems in the mesolimbic pathway may contribute to the 'positive symptoms' of schizophrenia (whereas problems with dopamine function in the mesocortical pathway may be responsible for the 'negative symptoms', such as avolition and alogia). Abnormal expression, thus distribution of the D₂ receptor between these areas and the rest of the brain may also be implicated in schizophrenia, specifically in the acute phase. A relative excess of these receptors within the limbic system means Broca's area, which can produce illogical language, has an abnormal connection to Wernicke's area, which comprehends language but does not create it. Note that variation in distribution is observed within individuals, so abnormalities of this characteristic likely play a significant role in all psychological illnesses. Individual alterations are produced by differences within glutamatergic pathways within the limbic system, which are also implicated in other psychotic syndromes. Among the alterations of both synaptic and global structure, the most significant abnormalities are observed in the uncinate fasciculus and the cingulate cortex. The combination of these creates a profound dissymmetry of prefrontal inhibitory signaling, shifted positively towards the dominant side. Eventually, the cingulate gyrus becomes atrophied towards the anterior, due to long-term depression (LTD) and long-term potentiation (LTP) from the abnormally strong signals transversely across the brain. This, combined with a relative deficit in GABAergic input to Wernicke's area, shifts the balance of bilateral communication across the corpus callosum posteriorly. Through this mechanism, hemispherical communication becomes highly shifted towards the left/dominant posterior. As such, spontaneous language from Broca's can propagate through the limbic system to the tertiary auditory cortex. This retrograde signaling to the temporal lobes that results in the parietal lobes not recognizing it as internal results in the auditory hallucinations typical of chronic schizophrenia.

In addition, significant cortical grey matter volume reductions are observed in this disorder. Specifically, the right hemisphere atrophies more, while both sides show a marked decrease in frontal and posterior volume. This indicates that abnormal synaptic plasticity occurs, where certain feedback loops become so potentiated, others receive little glutaminergic transmission. This is a direct result of the abnormal dopaminergic input to the striatum, thus (indirectly) disinhibition of thalamic activity. The excitatory nature of dopaminergic transmission means the glutamate hypothesis of schizophrenia is inextricably intertwined with this altered functioning. 5-HT also regulates monoamine neurotransmitters, including dopaminergic transmission. Specifically, the 5-HT2A receptor regulates cortical input to the basal ganglia and many typical and atypical antipsychotics are antagonists at this receptor. Several antipsychotics are also antagonists at the 5-HT2C receptor, leading to dopamine release in the structures where 5-HT2C is expressed; striatum, prefrontal cortex, nucleus accumbens, amygdala, hippocampus (all structures indicated in this disease), and currently thought to be a reason why antipsychotics with 5HT2C antagonistic properties improves negative symptoms. More research is needed to explain the exact nature of the altered chemical transmission in this disorder.

Recent evidence on a variety of animal models of psychosis, such as sensitization of animal behaviour by amphetamine, or phencyclidine (PCP, Angel Dust), or excess steroids, or by removing various genes (COMT, DBH, GPRK6, RGS9, RIIbeta), or making brain lesions in newborn animals, or delivering animals abnormally by Caesarian section, all induce a marked behavioural supersensitivity to dopamine and a marked rise in the number of dopamine D₂ receptors in the high-affinity state for dopamine. This latter work implies that there are multiple genes and neuronal pathways that can lead to psychosis and that all these multiple psychosis pathways converge via the high-affinity state of the D2 receptor, the common target for all antipsychotics, typical or atypical. Combined with less inhibitory signalling from the thalamus and other basal ganglic structures, from hyoptrophy the abnormal activation of the cingulate cortex, specifically around Broca's and Wernicke's areas, abnormal D₂ agonism can facilitate the self-reinforcing, illogical patterns of language found in such patients. In schizophrenia, this feedback loop has progressed, which produced the widespread neural atrophy characteristic of this disease. Patients on neuroleptic or antipsychotic medication have significantly less atrophy within these crucial areas. As such, early medical intervention is crucial in preventing the advancement of these profound deficits in bilateral communication at the root of all psychotic disorders. Advanced, chronic schizophrenia can not respond even to clozapine, regarded as the most potent antipsychotic, as such, a cure for highly advanced schizophrenia is likely impossible through the use of any modern antipsychotics, so the value of early intervention cannot be stressed enough.

Discussion

Evidence for the dopamine hypothesis

Amphetamine, cocaine and similar drugs increase levels of dopamine in the brain and can cause symptoms which resemble those present in psychosis, particularly after large doses or prolonged use. This is often referred to as "amphetamine psychosis" or "cocaine psychosis," but may produce experiences virtually indistinguishable from the positive symptoms associated with schizophrenia. Similarly, those treated with dopamine enhancing levodopa for Parkinson's disease can experience psychotic side effects mimicking the symptoms of schizophrenia. Up to 75% of patients with schizophrenia have increased signs and symptoms of their psychosis upon challenge with moderate doses of methylphenidate or amphetamine or other dopamine-like compounds, all given at doses at which control normal volunteers do not have any psychologically disturbing effects.

Some functional neuroimaging studies have also shown that, after taking amphetamine, patients diagnosed with schizophrenia show greater levels of dopamine release (particularly in the striatum) than non-psychotic individuals. However, the acute effects of dopamine stimulants include euphoria, alertness and over-confidence; these symptoms are more reminiscent of mania than schizophrenia. Since the 2000s, several PET studies have confirmed an altered synthesis capacity of dopamine in the nigrostriatal system demonstrating a dopaminergic dysregulation.

A group of drugs called the phenothiazines, including antipsychotics such as chlorpromazine, has been found to antagonize dopamine binding (particularly at receptors known as D₂ dopamine receptors) and reduce positive psychotic symptoms. This observation was subsequently extended to other antipsychotic drug classes, such as butyrophenones including haloperidol. The link was strengthened by experiments in the 1970s which suggested that the binding affinity of antipsychotic drugs for D₂ dopamine receptors seemed to be inversely proportional to their therapeutic dose. This correlation, suggesting that receptor binding is causally related to therapeutic potency, was reported by two laboratories in 1976.

Genetic evidence has suggested that there may be genes, or specific variants of genes, that code for mechanisms involved in dopamine function, which may be more prevalent in people experiencing psychosis or diagnosed with schizophrenia. Dopamine-related genes linked to psychosis in this way include COMT, DRD4, and AKT1.

People with Schizophrenia appear to have a high rate of self-medication with nicotine; the therapeutic effect likely occurs through dopamine modulation by nicotinic acetylcholine receptors.

However, there was controversy and conflicting findings over whether postmortem findings resulted from drug tolerance to chronic antipsychotic treatment. Compared to the success of postmortem studies in finding profound changes of dopamine receptors, imaging studies using SPET and PET methods in drug naive patients have generally failed to find any difference in dopamine D₂ receptor density compared to controls. Comparable findings in longitudinal studies show: " Particular emphasis is given to methodological limitations in the existing literature, including lack of reliability data, clinical heterogeneity among studies, and inadequate study designs and statistic," suggestions are made for improving future longitudinal neuroimaging studies of treatment effects in schizophrenia A recent review of imaging studies in schizophrenia shows confidence in the techniques, while discussing such operator error. In 2007 one report said, "During the last decade, results of brain imaging studies by use of PET and SPET in schizophrenic patients showed a clear dysregulation of the dopaminergic system." 

Recent findings from meta-analyses suggest that there may be a small elevation in dopamine D₂ receptors in drug-free patients with schizophrenia, but the degree of overlap between patients and controls makes it unlikely that this is clinically meaningful. While the review by Laruelle acknowledged more sites were found using methylspiperone, it discussed the theoretical reasons behind such an increase (including the monomer-dimer equilibrium) and called for more work to be done to 'characterise' the differences. In addition, newer antipsychotic medication (called atypical antipsychotic medication) can be as potent as older medication (called typical antipsychotic medication) while also affecting serotonin function and having somewhat less of a dopamine blocking effect. In addition, dopamine pathway dysfunction has not been reliably shown to correlate with symptom onset or severity. HVA levels correlate trendwise to symptoms severity. During the application of debrisoquin, this correlation becomes significant.

Giving a more precise explanation of this discrepancy in D₂ receptor has been attempted by a significant minority. Radioligand imaging measurements involve the monomer and dimer ratio, and the 'cooperativity' model. Cooperativitiy is a chemical function in the study of enzymes. Dopamine receptors interact with their own kind, or other receptors to form higher order receptors such as dimers, via the mechanism of cooperativity. Philip Seeman has said: "In schizophrenia, therefore, the density of [11C] methylspiperone sites rises, reflecting an increase in monomers, while the density of [11C] raclopride sites remains the same, indicating that the total population of D₂ monomers and dimers does not change." (In another place Seeman has said methylspiperone possibly binds with dimers) With this difference in measurement technique in mind, the above-mentioned meta-analysis uses results from 10 different ligands. Exaggerated ligand binding results such as SDZ GLC 756 (as used in the figure) were explained by reference to this monomer-dimer equilibrium.

According to Seeman, "...Numerous postmortem studies have consistently revealed D₂ receptors to be elevated in the striata of patients with schizophrenia". However, the authors were concerned the effect of medication may not have been fully accounted for. The study introduced an experiment by Abi-Dargham et al. in which it was shown medication-free live schizophrenics had more D₂ receptors involved in the schizophrenic process and more dopamine. Since then another study has shown such elevated percentages in D₂ receptors is brain-wide (using a different ligand, which did not need dopamine depletion). In a 2009 study, Annisa Abi-Dagham et al. confirmed the findings of her previous study regarding increased baseline D₂ receptors in schizophrenics and showing a correlation between this magnitude and the result of amphetamine stimulation experiments.

Some animal models of psychosis are similar to those for addiction – displaying increased locomotor activity. For those female animals with previous sexual experience, amphetamine stimulation happens faster than for virgins. There is no study on male equivalent because the studies are meant to explain why females experience addiction earlier than males.

Even in 1986 the effect of antipsychotics on receptor measurement was controversial. An article in Science sought to clarify whether the increase was solely due to medication by using drug-naive schizophrenics: "The finding that D₂ dopamine receptors are substantially increased in schizophrenic patients who have never been treated with neuroleptic drugs raises the possibility that dopamine receptors are involved in the schizophrenic disease process itself. Alternatively, the increased D₂ receptor number may reflect presynaptic factors such as increased endogenous dopamine levels (16). In either case, our findings support the hypothesis that dopamine receptor abnormalities are present in untreated schizophrenic patients."  (The experiment used 3-N-[11C]methylspiperone – the same as mentioned by Seeman detects D₂ monomers and binding was double that of controls.)

It is still thought that dopamine mesolimbic pathways may be hyperactive, resulting in hyperstimulation of D₂ receptors and positive symptoms. There is also growing evidence that, conversely, mesocortical pathway dopamine projections to the prefrontal cortex might be hypoactive (underactive), resulting in hypostimulation of D₁ receptors, which may be related to negative symptoms and cognitive impairment. The overactivity and underactivity in these different regions may be linked, and may not be due to a primary dysfunction of dopamine systems but to more general neurodevelopmental issues that precede them. Increased dopamine sensitivity may be a common final pathway.

Another finding is a six-fold excess of binding sites insensitive to the testing agent, raclopride; Seeman said this increase was probably due to the increase in D₂ monomers. Such an increase in monomers may occur via the cooperativity mechanism which is responsible for D₂^High and D₂^Low, the supersensitive and lowsensitivity states of the D₂ dopamine receptor. More specifically, "an increase in monomers, may be one basis for dopamine supersensitivity".

Evidence against the dopamine hypothesis

Further experiments, conducted as new methods were developed (particularly the ability to use PET scanning to examine drug action in the brain of living patients) challenged the view that the amount of dopamine blocking was correlated with clinical benefit. These studies showed that some patients had over 90% of their D₂ receptors blocked by antipsychotic drugs, but showed little reduction in their psychoses. This primarily occurs in patients who have had the psychosis for ten to thirty years. At least 90-95% of first-episode patients, however, respond to antipsychotics at low doses and do so with D₂ occupancy of 60-70%. The antipsychotic aripiprazole occupies over 90% of D₂ receptors, but this drug is both an agonist and an antagonist at D₂ receptors.

Furthermore, although dopamine-inhibiting medications modify dopamine levels within minutes, the associated improvement in patient symptoms is usually not visible for at least several days, suggesting that dopamine may be indirectly responsible for the illness.

Similarly, the second generation of antipsychotic drugs – the atypical antipsychotics) were found to be just as effective as older typical antipsychotics in controlling psychosis, but more effective in controlling the negative symptoms, despite the fact that they have lower affinity for dopamine receptors than for various other neurotransmitter receptors. More recent work, however, has shown that atypical antipsychotic drugs such as clozapine and quetiapine bind and unbind rapidly and repeatedly to the dopamine D₂ receptor. All of these drugs exhibit inverse agonistic effects at the 5-HT_2A/2C receptors, meaning serotonin abnormalities are also involved in the complex constellation of neurologic factors predisposing one to the self reinforcing language-based psychological deficits found in all forms of psychosis.

The excitatory neurotransmitter glutamate is now also thought to be associated with schizophrenia. Phencyclidine (also known as PCP or "Angel Dust") and ketamine, both of which block glutamate (NMDA) receptors, are known to cause psychosis at least somewhat resembling schizophrenia, further suggesting that psychosis and perhaps schizophrenia cannot fully be explained in terms of dopamine function, but may also involve other neurotransmitters.

Similarly, there is now evidence to suggest there may be a number of functional and structural anomalies in the brains of some people diagnosed with schizophrenia, such as changes in grey matter density in the frontal and temporal lobes. It appears, therefore, that there are multiple causes for psychosis and schizophrenia, including gene mutations and anatomical lesions.

Psychiatrist David Healy has argued that drug companies have inappropriately promoted the dopamine hypothesis of schizophrenia as a deliberate and calculated simplification for the benefit of drug marketing.

Relationship with glutamate

Research has shown the importance of glutamate receptors, specifically N-methyl-D-aspartate receptors (NMDARs), in addition to dopamine in the etiology of schizophrenia. Mice with only 5% of the normal levels of NMDAR's expressed schizophrenic like behaviors seen in animal models of schizophrenia while mice with 100% of NMDAR's behaved normally. Schizophrenic behavior in low NMDAR mice has been effectively treated with antipsychotics that lower dopamine. NMDAR's and dopamine receptors in the prefrontal cortex are associated with the cognitive impairments and working memory deficits commonly seen in schizophrenia. Rats that have been given a NMDAR antagonist exhibit a significant decrease in performance on cognitive tasks. Rats given a dopamine antagonist (antipsychotic) experience a reversal of the negative effects of the NMDAR antagonist. Glutamate imbalances appear to cause abnormal functioning in dopamine. When levels of glutamate are low dopamine is overactive and results in the expression schizophrenic symptoms.

Criticisms

Dr Ronald Pies, the current editor in Chief Emeritus of Psychiatric Times with a circulation of about 50,000 psychiatrists monthly, wrote on July 11, 2011 " In truth, the “chemical imbalance” notion was always a kind of urban legend- - never a theory seriously propounded by well-informed psychiatrists."

Combined networks of dopamine, serotonin, and glutamate

PsychopharmacologistStephen M. Stahl suggested in a review of 2018 that in many cases of psychosis, including schizophrenia, three interconnected networks based on dopamine, serotonin, and glutamate - each on its own or in various combinations - contributed to an overexcitation of dopamine D2 receptors in the ventral striatum.

Salience (neuroscience)

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Salience_(neuroscience) 

The salience (also called saliency) of an item is the state or quality by which it stands out from its neighbors. Saliency detection is considered to be a key attentional mechanism that facilitates learning and survival by enabling organisms to focus their limited perceptual and cognitive resources on the most pertinent subset of the available sensory data.

Saliency typically arises from contrasts between items and their neighborhood, such as a red dot surrounded by white dots, a flickering message indicator of an answering machine, or a loud noise in an otherwise quiet environment. Saliency detection is often studied in the context of the visual system, but similar mechanisms operate in other sensory systems. What is salient can be influenced by training: for example, for human subjects particular letters can become salient by training.

When attention deployment is driven by salient stimuli, it is considered to be bottom-up, memory-free, and reactive. Conversely, attention can also be guided by top-down, memory-dependent, or anticipatory mechanisms, such as when looking ahead of moving objects or sideways before crossing streets. Humans and other animals have difficulty paying attention to more than one item simultaneously, so they are faced with the challenge of continuously integrating and prioritizing different bottom-up and top-down influences.

Neuroanatomy

The brain component named the hippocampus helps with the assessment of salience and context by using past memories to filter new incoming stimuli, and placing those that are most important into long term memory. The entorhinal cortex is the pathway into and out of the hippocampus, and is an important part of the brain's memory network; research shows that it is a brain region that suffers damage early on in Alzheimer's disease, one of the effects of which is altered (diminished) salience.

The pulvinar nuclei (in the thalamus) modulates physical/perceptual salience in attentional selection.

One group of neurons (i.e., D1-type medium spiny neurons) within the nucleus accumbens shell (NAcc shell) assigns appetitive motivational salience ("want" and "desire", which includes a motivational component), aka incentive salience, to rewarding stimuli, while another group of neurons (i.e., D2-type medium spiny neurons) within the NAcc shell assigns aversive motivational salience to aversive stimuli.

The primary visual cortex (V1) generates a bottom-up saliency map from visual inputs to guide reflexive attentional shifts or gaze shifts. The saliency of a location is higher when V1 neurons give higher responses to that location relative to V1 neurons' responses to other visual locations. For example, a unique red item among green items, or a unique vertical bar among horizontal bars, is salient since it evokes higher V1 responses and attracts attention or gaze. The V1 neural responses are sent to the superior colluculus to guide gaze shifts to the salient locations. A fingerprint of the saliency map in V1 is that attention or gaze can be captured by the location of an eye-of-origin singleton in visual inputs, e.g., a bar uniquely shown to the left eye in a background of many other bars shown to the right eye, even when observers cannot tell the difference between the singleton and the background bars.

In psychology

The term is widely used in the study of perception and cognition to refer to any aspect of a stimulus that, for any of many reasons, stands out from the rest. Salience may be the result of emotional, motivational or cognitive factors and is not necessarily associated with physical factors such as intensity, clarity or size. Although salience is thought to determine attentional selection, salience associated with physical factors does not necessarily influence selection of a stimulus.

Salience bias

Salience bias (also known as perceptual salience) is the cognitive bias that predisposes individuals to focus on items that are more prominent or emotionally striking and ignore those that are unremarkable, even though this difference is often irrelevant by objective standards. Salience bias is closely related to the concept of availability in behavioral economics:

Accessibility and salience are closely related to availability, and they are important as well. If you have personally experienced a serious earthquake, you’re more likely to believe that an earthquake is likely than if you read about it in a weekly magazine. Thus, vivid and easily imagined causes of death (for example, tornadoes) often receive inflated estimates of probability, and less-vivid causes (for example, asthma attacks) receive low estimates, even if they occur with a far greater frequency (here, by a factor of twenty). Timing counts too: more recent events have a greater impact on our behavior, and on our fears, than earlier ones.

— Richard H. Thaler, Nudge: Improving Decisions about Health, Wealth, and Happiness (2008-04-08)

Aberrant salience hypothesis of schizophrenia

Kapur (2003) proposed that a hyperdopaminergic state, at a "brain" level of description, leads to an aberrant assignment of salience to the elements of one's experience, at a "mind" level. These aberrant salience attributions have been associated with altered activities in the mesolimbic system, including the striatum, the amygdala, the hippocampus, and the parahippocampal gyrus. Dopamine mediates the conversion of the neural representation of an external stimulus from a neutral bit of information into an attractive or aversive entity, i.e. a salient event. Symptoms of schizophrenia may arise out of 'the aberrant assignment of salience to external objects and internal representations', and antipsychotic medications reduce positive symptoms by attenuating aberrant motivational salience via blockade of the dopamine D2 receptors (Kapur, 2003).

Alternative areas of investigation include supplementary motor areas, frontal eye fields and parietal eye fields. These areas of the brain are involved with calculating predictions and visual salience. Changing expectations on where to look restructures these areas of the brain. This cognitive repatterning can result in some of the symptoms found in such disorders.

Visual saliency modeling

In the domain of psychology, efforts have been made in modeling the mechanism of human attention, including the learning of prioritizing the different bottom-up and top-down influences.

In the domain of computer vision, efforts have been made in modeling the mechanism of human attention, especially the bottom-up attentional mechanism, including both spatial and temporal attention. Such a process is also called visual saliency detection.

Generally speaking, there are two kinds of models to mimic the bottom-up saliency mechanism. One way is based on the spatial contrast analysis: for example, a center-surround mechanism is used to define saliency across scales, which is inspired by the putative neural mechanism.  The other way is based on the frequency domain analysis. While they used the amplitude spectrum to assign saliency to rarely occurring magnitudes, Guo et al. use the phase spectrum instead. Recently, Li et al. introduced a system that uses both the amplitude and the phase information.

A key limitation in many such approaches is their computational complexity leading to less than real-time performance, even on modern computer hardware. Some recent work attempts to overcome these issues at the expense of saliency detection quality under some conditions. Other work suggests that saliency and associated speed-accuracy phenomena may be a fundamental mechanisms determined during recognition through gradient descent, needing not be spatial in nature.

Analytical skill

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Analytical_skill 

 

The cerebral cortex is responsible for analytical thinking in the human brain

Analytical skill is the ability to deconstruct information into smaller categories in order to draw conclusions. Analytical skill consists of categories that include logical reasoning, critical thinking, communication, research, data analysis and creativity. Analytical skill is taught in contemporary education with the intention of fostering the appropriate practises for future professions. The professions that adopt analytical skill include educational institutions, public institutions, community organisations and industry. 

Richard J. Heuer Jr. explained that 'Thinking analytically is a skill like carpentry or driving a car. It can be taught, it can be learned, and it can improve with practice. But like many other skills, such as riding a bike, it is not learned by sitting in a classroom and being told how to do it. Analysts learn by doing.'. In the article by Freed, the need for programs within the educational system to help students develop these skills is demonstrated. According to scholars, workers 'will need more than elementary basic skills to maintain the standard of living of their parents. They will have to think for a living, analyse problems and solutions, and work cooperatively in teams'.

Logical Reasoning

Logical reasoning is a process comprising of inferences, where premises and hypotheses are formulated to arrive at a probable conclusion. It is a broad term comprising of three sub-classifications in deductive reasoning, inductive reasoning and abductive reasoning.

Deductive Reasoning

‘Deductive reasoning is a basic form of valid reasoning, commencing with a general statement or hypothesis, then examines the possibilities to reach a specific, logical conclusion’. This scientific method utilises deductions, to test hypotheses and theories, to predict if possible observations were correct. 

A logical deductive reasoning sequence can be executed by establishing: an assumption, followed by another assumption and finally, conducting an inference. For example, ‘All men are mortal. Harold is a man. Therefore, Harold is mortal.’

For deductive reasoning to be upheld, the hypothesis must be correct, therefore, reinforcing the notion that the conclusion is logical and true. It is possible for deductive reasoning conclusions to be inaccurate or incorrect entirely, but the reasoning and premise is logical. For example, ‘All bald men are grandfathers. Harold is bald. Therefore, Harold is a grandfather.’ is a valid and logical conclusion but it is not true as the original assumption is incorrect. Deductive reasoning is an analytical skill used in many professions such as management, as the management team delegates tasks for day-to-day business operations.

Inductive Reasoning

Inductive reasoning compiles information and data to establish a general assumption that is suitable to the situation. Inductive reasoning commences with an assumption based on faithful data, leading to a generalised conclusion. For example, ‘All the swans I have seen are white. (Premise) Therefore all swans are white. (Conclusion)’. It is clear that the conclusion is incorrect, therefore, it is a weak argument. To strengthen the conclusion, it is made more probable, for example, ‘All the swans I have seen are white. (Premise) Therefore most swans are probably white (Conclusion)’. Inductive reasoning is an analytical skill common in many professions such as the corporate environment, where statistics and data are constantly analysed.

Doctor using abductive reasoning to diagnose a man with diabetes

The 6 types of inductive reasoning

1. Generalised: This manner utilises a premise on a sample set to extract a conclusion about a population.
2. Statistical: This is a method that utilises statistics based on a large and viable random sample set that is quantifiable to strengthen conclusions and observations.
3. Bayesian: This form adapts statistical reasoning to account for additional or new data.
4. Analogical: This is a method that records on the foundations of shared properties between two groups, leading to a conclusion that they are also likely to share further properties.
5. Predictive: This form of reasoning extrapolates a conclusion about the future based on a current or past sample.
6. Casual inference: This method of reasoning is formed around a causal link between the premise and the conclusion.

Abductive reasoning

Abductive reasoning commences with layered hypotheses, which may be insufficient with evidence, leading to a conclusion that is most likely explanatory for the problem. It is a form of reasoning where the conductor chooses a hypothesis that would best suit the given data. For example, when a patient is ill, the doctor gathers a hypothesis from the patient’s symptoms, or other evidence, that they deem factual and appropriate. The doctor will then go through a list of possible illnesses and will attempt to assign the appropriate illness. Abductive reasoning is characterised by its lack of completeness, in evidence, explanation or both. This form of reasoning can be creative, intuitive and revolutionary due to its instinctive design.

Critical Thinking

Critical thinking is an analytical skill that involves clear, purposeful, and goal-directed thinking. It is used to interpret and explain the data given. It is the ability to think cautiously and rationally to resolve problems. This goal-directed thinking is achieved by supporting conclusions without biases, having reliable evidence and reasoning, and using appropriate data and information. Critical thinking is an imperative analytical skill as it underpins contemporary living in areas such as education and professional careers, but it is not restricted to a specific area.

Critical thinking is used to solve problems, calculate the likelihood, make decisions, and formulate inferences. Critical thinking requires examining information, reflective thinking, using appropriate skills, and confidence in the quality of the information given to come to a conclusion or plan. Critical thinking includes being willing to change if better information becomes available. As a critical thinker individuals do not accept assumptions without further questioning the reliability of it with further research and analysing the results found.

Developing Critical Thinking

Critical thinking can be developed through establishing personal beliefs and values. It is critical that individuals are able to query authoritative bodies: teachers, specialists, textbooks, books, newspapers, television etc. Querying these authorities allow critical thinking ability to be developed as the individual gains their own freedom and wisdom to think about reality and contemporary society, revering from autonomy.

Developing Critical Thinking through Probability Models

Critical thinking can be developed through probability models, where individuals adhere to a logical, conceptual understanding of mathematics and emphasise investigation, problem-solving, mathematical literacy and the use of mathematical discourse. The student actively constructs their knowledge and understanding, while teaching models function as a mediator by actively testing the student through querying, challenging and assigning investigation tasks, ultimately, allowing the student to think in deeper ways about various concepts, ideas and mathematical contexts.

Communication

Communication is a process where individuals transfer information from one another. It is a complex system comprising of a listener interpreting the information, understanding it and then transferring it. Communication as an analytical skill includes communicating with confidence, clarity, and sticking with the point you are trying to communicate. It comprises of verbal and non-verbal communication. Communication is an imperative component of analytical skill as it allows the individual to develop relationships, contribute to group decisions, organisational communication, and influence media and culture.

Dr. Martin Luther King Jr. providing a speech to 250,000 people during the Civil Rights March in Washington D.C. exemplifies verbal communication

Verbal Communication

Verbal communication is interaction through words in linguistic form. Verbal communication comprises of oral communication, written communication and sign language. It is an effective form of communication as the individuals sending and receiving the information are physically present, allowing immediate responses. In this form of communication, the sender uses words, spoken or written, to express the message to the individuals receiving the information.

Verbal communication is an essential analytical skill as it allows for the development of positive relationships among individuals. This positive relationship is attributed to the notion that verbal communication between individuals fosters a depth of understanding, empathy and versatility among them, providing each other with more attention. Verbal communication is a skill that is commonly used in professions such as the health sector, where healthcare workers are desired to possess strong interpersonal skills. Verbal communication has been linked to patient satisfaction. An effective strategy to improve verbal communication ability is through debating as is it fosters communication and critical thinking.

Non-verbal Communication

Non-verbal communication is commonly known as unspoken dialogue between individuals. It is a significant analytical skill as it allows individuals to distinguish true feelings, opinions and behaviours, as individuals are more likely to believe nonverbal cues as opposed to verbal expressions. Non-verbal communication is able to transcend communicational barriers such as race, ethnicity and sexual orientation. This is a significant factor for international industries that require global communication or communication between other regions such as trade between China and The United States of America.

Dancing is a common expressionist form of human non-verbal communication

 

Statistical measures showcase that the true meaning behind all messages is 93% non-verbal and 7% verbal. Non-verbal communication is a critical analytical skill as it allows individuals to delve deeper into the meaning of messages. It allows individuals to analyse another person’s perceptions, expressions and social beliefs. Individuals who excel in communicating and understanding non-verbal communication are able to analyse the interconnectedness of mutualism, social beliefs and expectations.

Communication Theories

A communication theory is an abstract understanding of how information is transferred from individuals. Many communication theories have been developed to foster and build upon the ongoing dynamic nature of how people communicate. Early models of communication were simple, such as Aristotle’s model of communication, comprising of a speaker communicating a speech to an audience, leading to an effect. This is a basic form of communication that addresses communication as a linear concept where information is not being relayed back.

Modern theories for communication include Schramm’s model where there are multiple individuals, each individual is encoding, interpreting and decoding the message, and messages are being transferred between one another. Schramm has included another factor in his model in experience i.e. expressing that each individual’s experience influences their ability to interpret a message. Communication theories are constantly being developed to acclimatise to certain organisations or individuals. It is imperative for an individual to adopt a suitable communication theory for organisations to ensure that the organisation is able to function as desired. For example, traditional corporate hierarchy are commonly known to adopt a linear communicational model i.e. Aristotle’s model of communication.

Research

Research is the construct of utilising tools and techniques to deconstruct and solve problems. While researching, it is important to distinguish what information is relevant to the data and avoiding excess, irrelevant data. Research involves the collection and analysis of information and data with the intention of founding new knowledge and/or deciphering a new understanding of existing data. Research ability is an analytical skill as it allows individuals to comprehend social implications. Research ability is valuable as it fosters transferable employment related skills. Research is primarily employed in academia and higher education, it is a profession pursued by many graduates, individuals intending to supervise or teach research students or those in pursuit of a PhD.

Research in Academia

In higher education, new research provides the most desired quality of evidence, if this is not available, then existing forms of evidence should be used. It is accepted that research provides the greatest form of knowledge, in the form of quantitative or qualitative data.

Research students are highly desired by various industries due to their dynamic mental capacity. Research students are commonly sought after due to their analysis and problem-solving ability, interpersonal and leadership skills, project management and organisation, research and information management and written and oral communication.

Data Analysis

Data analysis is a systematic method of cleaning, transforming and modelling statistical or logical techniques to describe and evaluate data. Using data analysis as an analytical skill means being able to examine large volumes of data and then identifying trends within the data. It is critical to be able to look at the data and determine what information is important and should be kept and what information is irrelevant and can be discarded. Data analysis includes finding different patterns within the information which allows you to narrow your research and come to a better conclusion. It is a tool to discover and decipher useful information for business decision-making. It is imperative in inferring information from data and adhering to a conclusion or decision from that data. Data analysis can stem from past or future data. Data analysis is an analytical skill, commonly adopted in business, as it allows organisations to be come more efficient, internally and externally, solve complex problems and innovate.

Text Analysis

Text analysis is the discovery and understanding of valuable information in unstructured or large data. It is a method to transform raw data into business information, allowing for strategic business decisions by offering a method to extract and examine data, derive patterns and finally interpret the data.

Statistical Analysis

Statistical analysis involves the collection, analyses and presentation of data to decipher trends and patterns. It is common in research, industry and government to enhance the scientific aspects of the decision that needs to be made. It consists of descriptive analysis and inferential analysis.

Descriptive Analysis

Descriptive analysis provides information about a sample set that reflects the population by summarising relevant aspects of the dataset i.e. uncovering patterns. It displays the measures of central tendency and measures of spread, such as mean, deviation, proportion, frequency etc.

Inferential Analysis

Inferential analysis analyses a sample from complete data to compare the difference between treatment groups. Multiple conclusions are constructed by selecting different samples. Inferential analysis can provide evidence that, with a certain percentage of confidence, there is a relationship between two variables. It is adopted that the sample will be different to the population, thus, we further accept a degree of uncertainty.

Example of sales forecasting, a form of predictive analysis

Diagnostic Analysis

Diagnostic analysis showcases the origin of the problem by finding the cause from the insight found in statistical analysis. This form of analysis is useful to identify behavioural patterns of data.

Predictive Analysis

Predictive analysis is an advanced form of analytics that forecasts future activity, behaviour, trends and patterns from new and historical data. Its accuracy is based on how much faithful data is present and the degree of inference that can be exploited from it.

Prescriptive Analysis

Prescriptive analytics provide firms with optimal recommendations to solve complex decisions. It is used in many industries, such as aviation to optimise schedule selection for airline crew.

Creativity

Areas of the brain that stimulated during actions of creativity

Creativity is important when it comes to solving different problems when presented. Creative thinking works best for problems that can have multiple solutions to solve the problem. It is also used when there seems to be no correct answer that applies to every situation, and is instead based from situation to situation. It includes being able to put the pieces of a problem together, as well as figure out pieces that may be missing. Then it includes brainstorming with all the pieces and deciding what pieces are important and what pieces can be discarded. The next step would be now analysing the pieces found to be of worth and importance and using those to come to a logical conclusion on how to best solve the problem. There can be multiple answers you come across to solve this problem. Many times creative thinking is referred to as right brain thinking. Creativity is an analytical skill as it allows individuals to utilise innovative methods to solve problems. Individuals that adopt this analytical skill are able to perceive problems from varying perspectives. This analytical skill is highly transferrable among professions.

Autodidacticism

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Autodidacticism 

Autodidacticism (also autodidactism) or self-education (also self-learning and self-teaching) is education without the guidance of masters (such as teachers and professors) or institutions (such as schools). Generally, autodidacts are individuals who choose the subject they will study, their studying material, and the studying rhythm and time. Autodidacts may or may not have formal education, and their study may be either a complement or an alternative to formal education. Many notable contributions have been made by autodidacts.

Etymology

The term has its roots in the Ancient Greek words αὐτός (autós, lit. ''self'') and διδακτικός (didaktikos, lit. ''teaching''). The related term didacticism defines an artistic philosophy of education.

Terminology

Various terms are used to describe self-education. One such is heutagogy, coined in 2000 by Stewart Hase and Chris Kenyon of Southern Cross University in Australia; others are self-directed learning and self-determined learning. In the heutagogy paradigm, a learner should be at the centre of their own learning.

Modern education

Autodidacticism is sometimes a complement of modern education. As a complement to education, students would be encouraged to do more independent work. The Industrial Revolution created a new situation for self-directed learners.

Before the twentieth century, only a small minority of people received an advanced academic education. As stated by Joseph Whitworth in his influential report on industry dated from 1853, literacy rates were higher in the United States. However, even in the U.S., most children were not completing high school. High school education was necessary to become a teacher. In modern times, a larger percentage of those completing high school also attended college, usually to pursue a professional degree, such as law or medicine, or a divinity degree.

Collegiate teaching was based on the classics (Latin, philosophy, ancient history, theology) until the early nineteenth century. There were few if any institutions of higher learning offering studies in engineering or science before 1800. Institutions such as the Royal Society did much to promote scientific learning, including public lectures. In England, there were also itinerant lecturers offering their service, typically for a fee.

Prior to the nineteenth century, there were many important inventors working as millwrights or mechanics who, typically, had received an elementary education and served an apprenticeship. Mechanics, instrument makers and surveyors had various mathematics training. James Watt was a surveyor and instrument maker and is described as being "largely self-educated". Watt, like some other autodidacts of the time, became a Fellow of the Royal Society and a member of the Lunar Society. In the eighteenth century these societies often gave public lectures and were instrumental in teaching chemistry and other sciences with industrial applications which were neglected by traditional universities. Academies also arose to provide scientific and technical training.

Years of schooling in the United States began to increase sharply in the early twentieth century. This phenomenon was seemingly related to increasing mechanization displacing child labor. The automated glass bottle-making machine is said to have done more for education than child labor laws because boys were no longer needed to assist. However, the number of boys employed in this particular industry was not that large; it was mechanization in several sectors of industry that displaced child labor toward education. For males in the U.S. born 1886–90, years of school averaged 7.86, while for those born in 1926–30, years of school averaged 11.46.

One of the most recent trends in education is that the classroom environment should cater towards students' individual needs, goals, and interests. This model adopts the idea of inquiry-based learning where students are presented with scenarios to identify their own research, questions and knowledge regarding the area. As a form of discovery learning, students in today's classrooms are being provided with more opportunity to "experience and interact" with knowledge, which has its roots in autodidacticism.

Successful self-teaching requires self-discipline and reflective capability. Some research suggests that being able to regulate one's own learning is something that must be modeled to students, for it is not a natural human tendency in the population at large. To interact with the environment, a framework has been identified to determine the components of any learning system: a reward function, incremental action value functions and action selection methods. Rewards work best in motivating learning when they are specifically chosen on an individual student basis. New knowledge must be incorporated into previously existing information as its value is to be assessed. Ultimately, these scaffolding techniques, as described by Vygotsky (1978) and problem solving methods are a result of dynamic decision making. 

The secular and modern societies gave foundations for a new system of education and a new kind of autodidacts. While the number of schools and students rose from one century to the other, so did the number of autodidacts. The industrial revolution produced new educational tools used in schools, universities and outside academic circles to create a post-modern era that gave birth to the World Wide Web and encyclopaedic data banks such as Wikipedia. As this concept becomes more widespread and popular, web locations such as Udacity and Khan Academy are developed as learning centers for many people to actively and freely learn together. The Alliance for Self-Directed Education (ASDE) is also formed to publicize and provide guidance or support for self-directed education.

In history, philosophy, literature, and television

The first philosophical claim supporting an autodidactic program to the study of nature and God was in the philosophical novel Hayy ibn Yaqdhan (Alive Son of the Vigilant), whose titular hero is considered the archetypal autodidact. The story is a medieval autodidactic utopia, a philosophical treatise in a literary form, which was written by the Andalusian philosopher Ibn Tufail in the 1160s in Marrakesh. It is a story about a feral boy, an autodidact prodigy who masters nature through instruments and reason, discovers laws of nature by practical exploration and experiments, and gains summum bonum through a mystical mediation and communion with God. The hero rises from his initial state of tabula rasa to a mystical or direct experience of God after passing through the necessary natural experiences. The focal point of the story is that human reason, unaided by society and its conventions or by religion, can achieve scientific knowledge, preparing the way to the mystical or highest form of human knowledge.

Commonly translated as "The Self-Taught Philosopher" or "The Improvement of Human Reason", Ibn-Tufayl's story Hayy Ibn-Yaqzan inspired debates about autodidacticism in a range of historical fields from classical Islamic philosophy through Renaissance humanism and the European Enlightenment. In his book Reading Hayy Ibn-Yaqzan: a Cross-Cultural History of Autodidacticism, Avner Ben-Zaken showed how the text traveled from late medieval Andalusia to early modern Europe and demonstrated the intricate ways in which autodidacticism was contested in and adapted to diverse cultural settings.

Autodidacticism apparently intertwined with struggles over Sufism in twelfth-century Marrakesh; controversies about the role of philosophy in pedagogy in fourteenth-century Barcelona; quarrels concerning astrology in Renaissance Florence in which Pico della Mirandola pleads for autodidacticism against the strong authority of intellectual establishment notions of predestination; and debates pertaining to experimentalism in seventeenth-century Oxford. Pleas for autodidacticism echoed not only within close philosophical discussions; they surfaced in struggles for control between individuals and establishments.

In the story of African American self-education, Heather Andrea Williams presents a historical account to examine African American's relationship to literacy during slavery, the Civil War and the first decades of freedom. Many of the personal accounts tell of individuals who have had to teach themselves due to racial discrimination in education.

The working-class protagonist of Jack London's Martin Eden (1909) embarks on a path of self-learning to win the affections of Ruth, a member of cultured society. By the end of the novel, Eden has surpassed the intellect of the bourgeois class, leading him to a state of indifference and ultimately suicide. 

Jean-Paul Sartre's Nausea (1938) depicts, as a secondary character, an autodidact. 

Comic-book superhero Batman is frequently depicted as an autodidactic polymath who has acquired a vast range of skills over the years either by various trainers or having trained himself, and his expertise in various disciplines is virtually unmatched in the DC comics universe. 

In The Ignorant Schoolmaster (1987), Jacques Rancière describes the emancipatory education of Joseph Jacotot, a post-Revolutionary philosopher of education who discovered that he could teach things he did not know. The book is both a history and a contemporary intervention in the philosophy and politics of education, through the concept of autodidacticism; Rancière chronicles Jacotot's "adventures", but he articulates Jacotot's theory of "emancipation" and "stultification" in the present tense.

The 1997 drama film Good Will Hunting follows the story of autodidact Will Hunting, played by Matt Damon. Hunting demonstrates his breadth and depth of knowledge throughout the film but especially to his therapist and in a heated discussion in a Harvard bar.

One of the main characters in The Elegance of the Hedgehog (2006), by Muriel Barbery, is an autodidact. The story is told from the viewpoint of Renee, a middle-aged autodidact concierge in a Paris upscale apartment house and Paloma, a 12-year-old daughter of one of the tenants who is unhappy with her life. These two people find they have much in common when they both befriend a new tenant, Mr. Ozu, and their lives change forever.

In the Hindu epic, the Mahabharata, Ekalavya is depicted as a tribal boy who was denied education in the science of arms from royal teachers from the house of Kuru. Ekalavya went to the forest, where he taught himself archery in front of an image of the Kuru teacher, Drona, that he had built for himself. Later, when the royal family found that Ekalavya had practiced with the image of Drona as his teacher, Drona asked for Ekalavya's thumb as part of his tuition. Ekalavya complied with Drona's request, thus ending his martial career.

In Suits, the protagonist (Mike Ross) possesses a highly competent knowledge of the law despite not receiving any formal education in any law school. His knowledge is attributable to both his affinity for reading (autodidacticism), in addition to his eidetic memory.

Dr. Spencer Reid in Criminal Minds, played by Matthew Gray Gubler, is an autodidact with an eidetic memory.

In architecture

Tadao Ando is a famous autodidact architect of the twenty-first century

 

Many successful and influential architects, such as Mies Van Der Rohe, Frank Lloyd Wright, Violet-Le-Duc, and Tadao Ando were self-taught.

There are very few countries allowing autodidacticism in architecture today. The practice of architecture or the use of the title "architect", are now protected in most countries.

Self-taught architects have generally studied and qualified in other fields such as engineering or arts and crafts. Jean Prouvé was first a structural engineer. Le Corbusier had an academic qualification in decorative arts. Tadao Ando started his career as a draftsman, and Eileen Gray studied fine arts.

When a political state starts to implement restrictions on the profession, there are issues related to the rights of established self-taught architects. In most countries the legislation includes a grandfather clause, authorising established self-taught architects to continue practicing. In the UK, the legislation, allowed self-trained architects with 2 years of experience to register. In France, it allowed self-trained architects with 5 years of experience to register. In Belgium, the law allowed experienced self-trained architects in practice to register. In Italy, it allowed self-trained architects with 10 years of experience to register. In The Netherlands, the "wet op de architectentitel van 7 juli 1987" along with additional procedures, allowed architects with 10 years of experience and architects aged 40 years old or over, with 5 years of experience, to access the register.

However, other sovereign states chose to omit such a clause, and many established and competent practitioners were stripped of their professional rights. In the Republic of Ireland, a group named "Architects' Alliance of Ireland" is defending the interests of long-established self-trained architects who were recently deprived from their rights to practice as per Part 3 of the Irish Building Control Act 2007.

Theoretical research such as "Architecture of Change, Sustainability and Humanity in the Built Environment" or older studies such as "Vers une Architecture" from Le Corbusier describe the practice of architecture as an environment changing with new technologies, sciences, and legislation. All architects must be autodidacts to keep up to date with new standards, regulations, or methods.

Self-taught architects such as Eileen Gray, Luis Barragán, and many others, created a system where working is also learning, where self-education is associated with creativity and productivity within a working environment.

While he was primarily interested in naval architecture, William Francis Gibbs learned his profession through his own study of battleships and ocean liners. Through his life he could be seen examining and changing the designs of ships that were already built, that is, until he started his firm Gibbs and Cox.

Future role

The role of self-directed learning continues to be investigated in learning approaches, along with other important goals of education, such as content knowledge, epistemic practices and collaboration. As colleges and universities offer distance learning degree programs and secondary schools provide cyber school options for K-12 students, technology provides numerous resources that enable individuals to have a self-directed learning experience. Several studies show these programs function most effectively when the "teacher" or facilitator is a full owner of virtual space to encourage a broad range of experiences to come together in an online format. This allows self-directed learning to encompass both a chosen path of information inquiry, self-regulation methods and reflective discussion among experts as well as novices in a given area. Furthermore, massive open online courses (MOOCs) make autodidacticism easier and thus more common.

A 2016 Stack Overflow poll reported that due to the rise of autodidacticism, 69.1% of software developers appear to be self-taught.