What is neuropsychology?

Introduction

Neuropsychology studies the relationships between brain functions and behaviors. It examines both human and animal nervous systems and tries to link biological organization and function of the nervous system to cognitive processing and behavior. Both healthy and damaged neural systems are examined. Although neuropsychology can be divided into a number of specialty areas, breaking the field into the branches of clinical neuropsychology and experimental neuropsychology serves to classify the primary types of work in which neuropsychologists are involved. This distinction is not absolute, of course.

Clinical Neuropsychology

Clinical neuropsychology involves the clinical testing of individuals who suffer from brain dysfunction, either developmental (genetic or chromosomal) or, more often, acquired (brain damage). Developmental disorders include Turner and Down syndromes; acquired disorders can be caused by problems such as fetal alcohol syndrome, brain lesions caused by tumors, cerebral vascular accidents (strokes), or head trauma.

Although neuropsychological evaluations once relied almost exclusively on paper-and-pencil tests to identify the probable location of a brain lesion and the resulting deficits, localization of lesions is typically handled through computerized brain imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI). Clinical neuropsychologists primarily assess a patient’s cognitive and behavioral deficits and describe the individual’s level of functioning. They are often involved in planning treatments and rehabilitation programs. Because damage to the same brain area may affect two individuals differently, it is vital that clinical neuropsychologists assess the effect of the lesion on the patient’s daily functioning at work, at home, and in social contexts. Furthermore, it is important that the evaluation consider the patient’s strengths in addition to weaknesses or impairments. Intact abilities can assist the patient in coping and compensating for the loss of other functions.

Brain Testing

Clinical neuropsychologists typically take one of two approaches with patients, the standard battery approach or the process approach. The standard battery approach is the older of the two and involves administering the same set of neurological tests to every patient. These tests typically demand different mental or cognitive abilities, which involve various regions of the brain. These different cognitive abilities are commonly referred to as cognitive domains and include functions such as attention, memory, perception, movement, language, and problem solving. A number of comprehensive test batteries have been created to assess these different skills, but two commonly used ones are the Halstead-Reitan and the Luria-Nebraska.

The process approach to clinical neuropsychology tailors the testing to the patient. It requires neuropsychologists to spend more one-on-one time with patients, and the tests chosen for each case can vary considerably. Essentially, neuropsychologists try to develop a hypothesis about the patient’s problems, then test it, and either accept or reject that hypothesis.

Each approach has its costs and benefits. The standard battery approach is cheaper and easier to use and teach. The process approach better recognizes the individuality of patients and can give a more comprehensive picture of an individual.

Experimental Neuropsychology

Experimental neuropsychology focuses on answering theoretical questions in the laboratory rather than solving clinical or practical problems in the outside world. Because of the invasive nature of their questions, experimental neuropsychologists often use animals rather than humans in their research. Only after a line of research has been proven safe and effective is it verified, wherever possible, with a human sample.

More than with most fields of psychology, advances in neuropsychology are determined by the technology available to researchers. An experimental neuropsychologist is usually familiar with the techniques of neurosurgery, primarily on animals, and with a variety of techniques, such as the staining of neurons, that help in examining brain structure. Neuropsychologists will certainly be familiar with electroencephalography (EEG), a recording of the brain’s electrical activity, and they often use direct electrical stimulation of the brain, at very low levels of current, in research. They commonly use brain imaging devices such as the CT or MRI. A high degree of technological expertise is demanded of the neuroscientist, but the result has been a rapid increase in knowledge about the relationship between the brain and behavior.

Although the daily routines of clinical and experimental neuropsychologists are quite different, their work often intertwines. The insights of experimental neuropsychologists often improve clinicians’ ability to assess and treat individuals with neurological impairment. Similarly, clinicians’ descriptions of interesting patients often open the road for further theoretical investigation by experimental neuropsychologists.

Practice and Theory

Overall, the field of neuropsychology has been useful in solving a number of practical problems as well as more theoretical ones. For example, clinical neuropsychological procedures have been applied in the assessment and treatment of individuals suspected of having Alzheimer’s disease. This disease is virtually impossible to confirm without removing and inspecting a sample of brain tissue under the microscope for the structural abnormalities that characterize the disorder. Therefore, a final diagnosis must wait until after the person’s death, at autopsy. However, neuropsychological test procedures have contributed dramatically to the accurate diagnosis of probable Alzheimer’s disease in still living individuals. A person with such a diagnosis is said to have senile dementia of the Alzheimer’s type (SDAT).

To family members of the Alzheimer’s patient, memory problems are often the first sign of trouble. However, a careful examination usually reveals subtle difficulties with language, problem solving, and visual-spatial activities such as navigating in the neighborhood or at home. Clinical neuropsychologists can investigate such problems by using a variety of pencil-and-paper tests to measure specific cognitive and behavioral functions. The patient is then tested serially at six-month intervals, and the overall pattern of test scores across time is evaluated. If the patient displays a pattern of declining performance across two or more cognitive domains (for example, memory and language), a diagnosis of dementia is supported. In addition, neuroimaging techniques such as the MRI are used to evaluate potential structural damage to the brain. Brain scans cannot reveal the microscopic plaques and tangles of neural tissue that characterize Alzheimer’s, but they can reveal large-scale neuron loss and can be used to eliminate other possible causes for the symptoms, such as a tumor or stroke.

Along with the measurement of various cognitive functions, neuropsychology also seems particularly well equipped to investigate other aspects of Alzheimer’s. Although a patient’s performance on a test battery is certainly helpful, other factors must be considered in diagnosing the disorder. For example, depression, hallucinations, delusions, and verbal or physical outbursts are often common with the disease. Because of this diverse collection of psychological and behavioral symptoms, clinical neuropsychology may be the best source of services for such patients.

A rapidly expanding field of endeavor for modern neuropsychologists involves work with recovery and rehabilitation efforts for brain-injured patients. The primary purpose is to reeducate and retrain brain-injured individuals for reentry into job and home settings, which usually means working with both the patient and the family. Often, people with brain injuries do not struggle equally in all cognitive domains. They may, for example, have particular problems with attention or language. Clinical neuropsychologists focus their efforts on the affected domain, bringing in other specialists as needed for physical, occupational, or speech therapy.

Generally, rehabilitation involves intensive exposure to situations involving the problematic cognitive task. For example, automobile accidents often result in damage to the frontal areas of the brain. Such patients typically lack appropriate social skills and have problems with planning and organizing their behaviors. Rehabilitation efforts might entail placement in group situations in which social skills can be practiced. Specific activities might include working on conversation skills, role-playing a job interview or asking for a date, or working on a group project. Individual sessions with the patient might be better suited for the treatment of the organizational and planning deficits experienced by frontal patients. Here, the neuropsychologist might teach the patient to use a diary for planning the week’s activities. Increasingly, computer technology is being used in rehabilitation, either to assist with training simulations, or to act as an actual prosthetic aid for tasks such as speech production.

Although neuropsychologists often assist patients in acquiring compensation strategies to work around their particular difficulties, there are other rationales for rehabilitative efforts. Many researchers believe that practicing an impaired function assists the healing brain in the recovery of that function. There appears to be a six- to twelve-month period immediately after a brain injury when the brain is developing pathways around the damaged tissue. Many believe that during this critical period, it is important to engage the patient in those activities most compromised by the injury. Therefore, if the injury took a major toll on memory abilities, the patient should be exposed to exercises and activities that demand remembering.

In general, neuropsychology has tremendous applied value for persons who have sustained a neurological insult such as a stroke or brain injury. Furthermore, it is useful in the initial assessment and accurate diagnosis of a given neurological disorder, as well as in the continued care and treatment of individuals with known brain pathology.

Brain Study

The term neuropsychology appears to have been coined by Sir William Osler, sometimes called the father of modern medicine, in an address at Johns Hopkins Hospital in 1913. The field really began to expand, however, after Donald O. Hebb, often called the father of neuropsychology, published The Organization of Behavior: A Neuropsychological Theory (1949). This book introduced Hebb’s concept of neural networks, which remains a unifying theme for modern neuropsychologists. The 1970s and 1980s were a particularly explosive time in the development of neuropsychology, with many new training programs springing up. Funding for all subfields of neuroscience increased dramatically when the US Congress designated the 1990s as the Decade of the Brain.

Although the field is relatively young, neuropsychology’s underpinnings can be traced back thousands of years. Ancient peoples from both Europe and the Americas engaged in trephination, the cutting of holes in the skull, presumably as a treatment for some sort of physical or behavioral problem. Ancient Egyptian and Greek writings also describe the results of brain injury, including the behaviors of patients. A theory of brain functioning was put forth in the nineteenth century by Franz Gall, the founder of phrenology, who thought specific areas of the brain were responsible for specific behavioral traits, and that brain abilities could be “read” by studying the shape of people’s skulls.

Although phrenology was eventually discredited, the nineteenth century also produced Paul Broca
, a pioneer in the study of brain anatomy. Broca demonstrated that a lesion of the left frontal lobe of the brain disrupted speech production. Inspired by Broca’s work, some researchers became consumed with localizing all cognitive functions to a discrete part of the brain. These scientists became known as localizationists. In contrast, investigators who believed that all areas of the brain were equally involved in all cognitive abilities were labeled equipotentialists. A third group, known as interactionists, suggested that basic cognitive functions were relatively localized but interacted to allow for complex cognitive processes. This perspective was derived from the late nineteenth century research of John Hughlings Jackson and remains a prominent view in the twenty-first century.

The twentieth century witnessed a steady accumulation of knowledge concerning the relationships between brain and behavior. Much of this knowledge developed out of the need to assist soldiers who had sustained brain injuries in the two world wars. In treating these individuals, much was learned about the role of specific brain regions in carrying out various behaviors. A major contribution to the neurosciences in the twentieth century was made by the Soviet neuropsychologist Aleksandr Luria, whose systematic study of brain-injured people contributed tremendously to the process of assessing and localizing brain dysfunction.

This wealth of new knowledge has given clinical psychologists a much more sophisticated understanding of how best to treat patients with behavioral difficulties. It has also removed some of the stigma attached to mental illness or dysfunction. The lay public seems more willing to tolerate atypical behavior from an individual with physical damage to the brain than from a patient labeled as mentally ill.

The future appears to be full of promise for the field of neuropsychology. Although it may be years, if ever, before a complete understanding of the brain is achieved, the steady growth in new knowledge and new applications for that knowledge has already enriched the lives of countless human beings with brain dysfunctions. New insights into diseases such as Alzheimer’s promise to help many more people. Furthermore, as an understanding of the brain’s effects on behavior grows, the diverse subfields of psychology are bound ever closer together.

Bibliography

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