Chapter 2: Cognitive neuroscience

The study of the biological processes and factors that underlie cognitive functioning is the focus of the field of science known as cognitive neuroscience, Parts of the brain play a significant role in this sector. Neurons play the most vital role, since the main point is to establish an understanding of cognition from a neural perspective, along with the different lobes of the cerebral cortex.

Methods applied in cognitive neuroscience include experimental methods 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. The damages in lesioned brains provide a comparable starting point on regards to healthy and fully functioning brains. These damages change the neural circuits in the brain and cause it to malfunction during basic cognitive processes, such as memory or learning. People have learning disabilities and such damage, can be compared with how the healthy neural circuits are functioning, and possibly draw conclusions about the basis of the affected cognitive processes. Some examples of learning disabilities in the brain include places in Wernicke's area, the left side of the temporal lobe, and Brocca's area close to the frontal lobe.

Also, cognitive abilities based on brain development are studied and examined under the subfield of developmental cognitive neuroscience. This shows brain development over time, analyzing differences and concocting possible reasons for those differences.

Theoretical approaches include computational neuroscience and cognitive psychology.

Cognitive neuroscience is an interdisciplinary area of study that has emerged from neuroscience and psychology. These fields have gone through a number of stages, each of which has resulted in a distinct shift in the way in which researchers approach their work, ultimately leading to the establishment of the field in its entirety.

Although the task of cognitive neuroscience is to describe the neural mechanisms associated with 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, 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.

Philosophers have always been interested in the mind: "the idea that explaining a phenomenon involves understanding the mechanism responsible for it has deep roots in the History of Philosophy from atomic theories in 5th century B.C. to its rebirth in the 17th and 18th century in the works of Galileo, Descartes, and Boyle. Among others, it's Descartes' idea that machines humans build could work as models of scientific explanation." 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, 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. Franz Joseph Gall and J. G. Spurzheim were two scientists who, at the beginning of the 19th century, held the belief that the human brain could be divided into about 35 distinct regions. 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 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. It was crucial to future knowledge of the brain lobes.

The aggregate field view maintains that all regions of the brain are involved in the performance of each and every mental activity.

Perhaps the first serious attempts to localize mental functions to specific locations in the brain was by Broca and Wernicke. This was largely obtained through researching the impact of damage to various areas of the brain on psychological functions.

In 1870, German doctors Eduard Hitzig and Gustav Fritsch published their observations concerning the behavior of animals. Hitzig and Fritsch conducted an experiment on a dog in which they passed an electric current through the dog's cerebral cortex. The experiment caused various muscles to contract depending on which parts of the dog's brain were stimulated by the electrical current. Because of this, the proposition that individual functions are localized to specific regions of the brain rather than the cerebrum as a whole, as the aggregate field view suggests, emerged as a result of the research. Brodmann was also an important figure in brain mapping; his experiments based on Franz Nissl's tissue staining techniques divided the brain into fifty-two areas.

At the turn of the 20th century, pragmatic attitudes prevailed in the United States, which resulted in a preference for behaviorism as the primary approach in psychology. This preference lasted for the majority of the century. J.B. Watson was an important figure because of the stimulus-response method that he developed. He wanted to be able to foresee and regulate behavior, thus he conducted experiments on animals to try to achieve this goal. Behaviorism was ultimately unsuccessful due to the fact that it was unable to provide a realistic psychology of human action and thought. Instead, its primary emphasis was placed on stimulus-response associations, at the expense of explaining phenomena such as thought and imagination. This led to what is often termed as the "cognitive revolution".

In the early 20th century, Santiago Ramón y Cajal and Camillo Golgi began working on the structure of the neuron.

Golgi developed a silver staining method that could entirely stain several cells in a particular area, leading him to believe that neurons were directly connected with each other in one cytoplasm.

Cajal challenged this view after staining areas of the brain that had less myelin and discovering that neurons were discrete cells.

Cajal also observed that cells transfer electrical information down the neuron in one way only.

In 1906, the Nobel Prize in Physiology or Medicine was bestowed upon both Golgi and Cajal in recognition of their contributions to the neuron doctrine.

Several findings in the 20th century continued to advance the field, such as the discovery of ocular dominance columns, recording of single nerve cells in animals, and coordination of eye and head movements. Experimental psychology was also significant in the foundation of cognitive neuroscience. Some particularly important results were the demonstration that some tasks are accomplished via discrete processing stages, the study of attention, and the notion that behavioural data do not provide enough information by themselves to explain mental processes. As a result, some experimental psychologists began to investigate neural bases of behaviour. Wilder Penfield created maps of primary sensory and motor areas of the brain by stimulating the cortices of patients during surgery. The work of Sperry and Gazzaniga on split brain patients in the 1950s was also instrumental in the progress of the field.

New brain mapping technology, particularly fMRI and PET, allowed researchers to investigate experimental strategies of cognitive psychology by observing brain function. Although many people consider this to be a relatively new method (the majority of the technology involved is only a few decades old), the fundamental concept behind it dates all the way back to 1878, when blood flow was first associated with brain function.

The Massachusetts Institute of Technology hosted a significant gathering of cognitivists on September 11, 1956. The event was attended by a large number of people. George A. Miller presented his "The Magical Number Seven, Plus or Minus Two" paper

Before the 1980s, there was very little interaction between the fields of neuroscience and cognitive science.

Adaptive resonance theory (ART) is a cognitive neuroscience theory developed by Gail Carpenter and Stephen Grossberg in the late 1970s on aspects of how the brain processes information. It describes a number of neural network models which use supervised and unsupervised learning methods, and address problems such as pattern recognition and prediction.

Recently the focus of research had expanded from the localization of brain area(s) for specific functions in the adult brain using a single technology. Studies have been diverging in several different directions: exploring the interactions between different brain areas, using multiple technologies and approaches to understand brain functions, and using computational...