Neuropsychology

Neuropsychology is the study of the structure and function of the brain as they relate to specific psychological processes and behaviours.[1] It is both an experimental and clinical field of psychology that aims to understand how behavior and cognition are influenced by brain functioning and is concerned with the diagnosis and treatment of behavioral and cognitive effects of neurological disorders. Whereas classical neurology focuses on the physiology of the nervous system and classical psychology is largely divorced from it, neuropsychology seeks to discover how the brain correlates with the mind. It thus shares concepts and concerns with neuropsychiatry and with behavioral neurology in general. The term neuropsychology has been applied to lesion studies in humans and animals. It has also been applied in efforts to record electrical activity from individual cells (or groups of cells) in higher primates (including some studies of human patients).[2] It makes use of neuroscience, and shares an information processing view of the mind with cognitive psychology and cognitive science.

In practice, neuropsychologists tend to work in research settings (universities, laboratories or research institutions), clinical settings (medical hospitals or rehabilitation settings, often involved in assessing or treating patients with neuropsychological problems), or forensic settings or industry (often as clinical-trial consultants where CNS function is a concern).

History

Neuropsychology is a relatively new discipline within the field of psychology. The first textbook defining the field, Fundamentals of Human Neuropsychology, was initially published by Kolb and Whishaw in 1980.[3] However, the history of its development can be traced back to the Third Dynasty in ancient Egypt, perhaps even earlier.[4] There is much debate as to when societies started considering the functions of different organs. For many centuries, the brain was thought useless and was often discarded during burial processes and autopsies. As the field of medicine developed its understanding of human anatomy and physiology, different theories were developed as to why the body functioned the way it did. Many times, bodily functions were approached from a religious point of view and abnormalities were blamed on bad spirits and the gods. The brain has not always been considered the center of the functioning body. It has taken hundreds of years to develop our understanding of the brain and how it affects our behaviors.

Ancient Egypt

In ancient Egypt, writings on medicine date from the time of the priest Imhotep.[5] They took a more scientific approach to medicine and disease, describing the brain, trauma, abnormalities, and remedies for reference for future physicians. Despite this, Egyptians saw the heart not the brain as the seat of the soul.[6]

Aristotle

Senses, perception, memory, dreams, action in Aristotle's biology. Impressions are stored in the seat of perception, linked by his Laws of Association (similarity, contrast, and contiguity).[7]

Aristotle reinforced this focus on the heart which originated in Egypt. He believed the heart to be in control of mental processes, and looked on the brain, due to its inert nature, as a mechanism for cooling the heat generated by the heart.[8][9] He drew his conclusions based on the empirical study of animals. He found that while their brains were cold to the touch and that such contact did not trigger any movements, the heart was warm and active, accelerating and slowing dependent on mood.[8][9] Such beliefs were upheld by many for years to come, persisting through the Middle Ages and the Renaissance period until they began to falter in the 17th Century due to further research.[9] The influence of Aristotle in the development of neuropsychology is evident within language used in modern day, since we "follow our hearts" and "learn by the heart".[9]

Hippocrates

Hippocrates looked upon the brain as the seat of the soul. He drew a connection between the brain and behaviors of the body saying "The brain exercises the greatest power in the man".[10] Apart from moving the focus from the heart as the "seat of the soul" to the brain, Hippocrates did not go into much detail about its actual functioning. However, by switching the attention of the medical community to the brain, the doors were opened to a more scientific discovery of the organ responsible for our behaviors. For years to come, scientists were inspired to explore the functions of the body and to find concrete explanations for both normal and abnormal behaviors. Scientific discovery led them to believe that there were natural and organically occurring reasons to explain various functions of the body, and it could all be traced back to the brain. Over the years, science would continue to expand and the mysteries of the world would begin to make sense, or at least be looked at in a different way. Hippocrates introduced man to the concept of the mind – which was widely seen as a separate function apart from the actual brain organ.

René Descartes

Philosopher René Descartes expanded upon this idea and is most widely known by his work on the mind-body problem. Often, Descartes' ideas were looked upon as overly philosophical and lacking in sufficient scientific background. Descartes focused much of his anatomical experimentation on the brain, paying specific attention to the pineal gland – which he argued was the actual "seat of the soul". Still deeply rooted in a spiritual outlook towards the scientific world, the body was said to be mortal, and the soul immortal. The pineal gland was then thought to be the very place at which the mind would interact with the mortal and machine-like body. At the time, Descartes was convinced the mind had control over the behaviors of the body (controlling the man) – but also that the body could have influence over the mind, which is referred to as dualism.[11] This idea that the mind essentially had control over the body, but man's body could resist or even influence other behaviors was a major turning point in the way many physiologists would look at the brain. The capabilities of the mind were observed to do much more than simply react, but also to be rational and function in organized, thoughtful ways – much more complex than he thought the animal world to be. These ideas, although disregarded by many and cast aside for years led the medical community to expand their own ideas of the brain and begin to understand in new ways just how intricate the workings of the brain really were, and the complete effects it had on daily life, as well, which treatments would be the most beneficial to helping those people living with a dysfunctional mind. The mind-body problem, spurred by René Descartes, continues to this day with many philosophical arguments both for and against his ideas. However controversial they were and remain today, the fresh and well-thought-out perspective Descartes presented has had long-lasting effects on the various disciplines of medicine, psychology and much more, especially in putting an emphasis on separating the mind from the body in order to explain observable behaviors.

Thomas Willis

It was in the mid-17th century that another major contributor to the field of neuropsychology emerged. Thomas Willis studied at Oxford University and took a physiological approach to the brain and behavior. It was Willis who coined the words 'hemisphere' and 'lobe' when referring to the brain.[12] He was one of the earliest to use the words 'neurology' and 'psychology'. Rejecting the idea that humans were the only beings capable of rational thought, Willis looked at specialized structures of the brain.[9] He theorized that higher structures accounted for complex functions, whereas lower structures were responsible for functions similar to those seen in other animals, consisting mostly of reactions and automatic responses.[13] He was particularly interested in people who suffered from manic disorders and hysteria.[14][15] His research constituted some of the first times that psychiatry and neurology came together to study individuals. Through his in-depth study of the brain and behavior, Willis concluded that automated responses such as breathing, heartbeats and other various motor activities were carried out within the lower region of the brain. Although much of his work has been made obsolete, his ideas presented the brain as more complex than previously imagined, and led the way for future pioneers to understand and build upon his theories, especially when it came to looking at disorders and dysfunctions of the brain.[14]

Franz Joseph Gall

Neuroanatomist and physiologist Franz Joseph Gall made major progress in understanding the brain. He theorized that personality was directly related to features and structures within the brain. However, Gall's major contribution within the field of neuroscience is his invention of phrenology. This new discipline looked at the brain as an organ of the mind, where the shape of the skull could ultimately determine one's intelligence and personality.[16] This theory was like many circulating at the time, as many scientists were taking into account physical features of the face and body, head size, anatomical structure, and levels of intelligence; only Gall looked primarily at the brain. There was much debate over the validity of Gall's claims however, because he was often found to be wrong in his predictions. He was once sent a cast of René Descartes' skull, and through his method of phrenology claimed the subject must have had a limited capacity for reasoning and higher cognition.[17] As controversial and false as many of Gall's claims were, his contributions to understanding cortical regions of the brain and localized activity continued to advance understanding of the brain, personality, and behavior. His work is considered crucial to having laid a firm foundation in the field of neuropsychology, which would flourish over the next few decades.

Jean-Baptiste Bouillaud

Jean-Baptiste Bouillaud

Towards the late 19th century, the belief that the size of ones skull could determine their level of intelligence was discarded as science and medicine moved forward. A physician by the name of Jean-Baptiste Bouillaud expanded upon the ideas of Gall and took a closer look at the idea of distinct cortical regions of the brain each having their own independent function. Bouillaud was specifically interested in speech and wrote many publications on the anterior region of the brain being responsible for carrying out the act of ones speech, a discovery that had stemmed from the research of Gall. He was also one of the first to use larger samples for research although it took many years for that method to be accepted. By looking at over a hundred different case studies, Bouillaud came to discover that it was through different areas of the brain that speech is completed and understood. By observing people with brain damage, his theory was made more concrete. Bouillaud, along with many other pioneers of the time made great advances within the field of neurology, especially when it came to localization of function. There are many arguable debates as to who deserves the most credit for such discoveries,[18] and often, people remain unmentioned, but Paul Broca is perhaps one of the most famous and well known contributors to neuropsychology – often referred to as "the father" of the discipline.

Paul Broca

Inspired by the advances being made in the area of localized function within the brain, Paul Broca committed much of his study to the phenomena of how speech is understood and produced. Through his study, it was discovered and expanded upon that we articulate via the left hemisphere. Broca's observations and methods are widely considered to be where neuropsychology really takes form as a recognizable and respected discipline. Armed with the understanding that specific, independent areas of the brain are responsible for articulation and understanding of speech, the brains abilities were finally being acknowledged as the complex and highly intricate organ that it is. Broca was essentially the first to fully break away from the ideas of phrenology and delve deeper into a more scientific and psychological view of the brain.[19]

Karl Spencer Lashley

Karl Lashley (1890–1958) attended West Virginia University, where he was introduced to zoology and eventually decided to study the behavior of organisms. He got his master's degree in Bacteriology from the University of Pittsburgh, and then his PhD in Genetics from Johns Hopkins University where he minored in psychology under John B. Watson, whom he continued to work closely with after receiving his PhD. It was during this time that Lashley worked with Franz and was introduced to his training/ablation method. Lashley worked at the University of Minnesota for a time and then at the Institute for Juvenile Research in Chicago before becoming a professor at the University of Chicago. After this he went to Harvard, but was dissatisfied and from there became the director of the Yerkes Laboratory of Primate Biology in Orange Park, Florida. Lashley has always been viewed as an objective scientist, but Nadine Weidman has tried to expose him as a racist and a genetic determinist. But Donald Dewsbury and others, have disputed the claim that he was a genetic determinist, citing research of Lashley's in which he found evidence of both genetic and environmental influences on organisms. Dewsbury does admit however, that Lashley was quite racist. He cites a line from a letter that Lashley wrote to a German colleague which reads: "Too bad that the beautiful tropical countries are all populated by negros. Heil Hitler and Apartheit!"[20] This line alone would leave little debate on this matter, but he cites others as well. Despite his racism, Lashley has done some important work in neuropsychology and influenced his students to reach even greater heights. His works and theories that follow are summarized in his book Brain Mechanisms and Intelligence.[21] Lashley's theory of the Engram was the driving force for much of his research. An engram was believed to be a part of the brain where a specific memory was stored. He continued to use the training/ablation method that Franz had taught him. He would train a rat to learn a maze and then use systematic lesions and removed sections of cortical tissue to see if the rat forgot what it had learned. Through his research with the rats, he learned that forgetting was dependent on the amount of tissue removed and not where it was removed from. He called this mass action and he believed that it was a general rule that governed how brain tissue would respond, independent of the type of learning. But we know now that mass action was true for these rats, because learning to run a maze is known as complex learning and it requires multiple cortical areas, so cutting into individual parts alone will not erase the memory from the rats' brains, but taking large sections removes multiple cortical areas at one time and so they can forget. Lashley also discovered that a portion of a functional area could carry out the role of the entire area, even when the rest of the area has been removed. He called this phenomenon equipotentiality. We know now that he was seeing evidence of plasticity in the brain. The brain has the spectacular ability for certain areas to take over the functions of other areas if those areas should fail or be removed.

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