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Cognitive neuroscience is an academic field concerned with the scientific study of biological substrates underlying cognition, with a specific focus on the neural substrates of mental processes. It addresses the questions of how psychological/cognitive functions are produced by neural circuits in the brain. Cognitive neuroscience is a branch of both psychology and neuroscience, overlapping with disciplines such as physiological psychology, cognitive psychology, and neuropsychology. Cognitive neuroscience relies upon theories in cognitive science coupled with evidence from neuropsychology, and computational modeling.
Due to its multidisciplinary nature, cognitive neuroscientists may have various backgrounds. Other than the associated disciplines just mentioned, cognitive neuroscientists may have backgrounds in neurobiology, bioengineering, psychiatry, neurology, physics, computer science, linguistics, philosophy, and mathematics.
Methods employed in cognitive neuroscience include experimental paradigms from psychophysics and cognitive psychology, functional neuroimaging, electrophysiology, cognitive genomics, and behavioral genetics. Studies of patients with cognitive deficits due to brain lesions constitute an important aspect of cognitive neuroscience. Theoretical approaches include computational neuroscience and cognitive psychology.
Cognitive neuroscience can look at the effects of damage to the brain and subsequent changes in the thought processes due to changes in neural circuitry resulting from the ensued damage. Also, cognitive abilities based on brain development is studied and examined under the subfield of developmental cognitive neuroscience.
Cognitive neuroscience is an interdisciplinary area of study that has emerged from many other fields, perhaps most significantly neuroscience, psychology, and computer science. There were several stages in these disciplines that changed the way researchers approached their investigations and that led to the field becoming fully established.
Although the task of cognitive neuroscience is to describe how the brain creates the mind, historically it has progressed by investigating how a certain area of the brain supports a given mental faculty. However, early efforts to subdivide the brain proved to be problematic. The phrenologist movement failed to supply a scientific basis for its theories and has since been rejected. The aggregate field view, meaning that all areas of the brain participated in all behavior, was also rejected as a result of brain mapping, which began with Hitzig and Fritsch’s experiments  and eventually developed through methods such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). Gestalt theory, neuropsychology, and the cognitive revolution were major turning points in the creation of cognitive neuroscience as a field, bringing together ideas and techniques that enabled researchers to make more links between behavior and its neural substrates.
Origins in philosophyPhilosophers have always been interested in the mind. For example, Aristotle thought the brain was the body’s cooling system and the capacity for intelligence was located in the heart. It has been suggested that the first person to believe otherwise was the Roman physician Galen in the second century AD, who declared that the brain was the source of mental activity  although this has also been accredited to Alcmaeon. Psychology, a major contributing field to cognitive neuroscience, emerged from philosophical reasoning about the mind.
Main article: Phrenology
One of the predecessors to cognitive neuroscience was phrenology, a pseudoscientific approach that claimed that behavior could be determined by the shape of the scalp. In the early 19th century, Franz Joseph Gall and J. G. Spurzheim believed that the human brain was localized into approximately 35 different sections. In his book, The Anatomy and Physiology of the Nervous System in General, and of the Brain in Particular, Gall claimed that a larger bump in one of these areas meant that that area of the brain was used more frequently by that person. This theory gained significant public attention, leading to the publication of phrenology journals and the creation of phrenometers, which measured the bumps on a human subject's head. While phrenology remained a fixture at fairs and carnivals, it did not enjoy wide acceptance within the scientific community. The major criticism of phrenology is that researchers were not able to test theories empirically.
Localizationist viewThe localizationist view was concerned with mental abilities being localized to specific areas of the brain rather than on what the characteristics of the abilities were and how to measure them. Studies performed in Europe, such as those of John Hughlings Jackson, supported this view. Jackson studied patients with brain damage, particularly those with epilepsy. He discovered that the epileptic patients often made the same clonic and tonic movements of muscle during their seizures, leading Jackson to believe that they must be occurring in the same place every time. Jackson proposed that specific functions were localized to specific areas of the brain, which was critical to future understanding of the brain lobes.
Aggregate field viewAccording to the aggregate field view, all areas of the brain participate in every mental function.
Pierre Flourens, a French experimental psychologist, challenged the localizationist view by using animal experiments. He discovered that removing the cerebellum in rabbits and pigeons affected their sense of muscular coordination, and that all cognitive functions were disrupted in pigeons when the cerebral hemispheres were removed. From this he concluded that the cerebral cortex, cerebellum, and brainstem functioned together as a whole. His approach has been criticised on the basis that the tests were not sensitive enough to notice selective deficits had they been present.