Contents
- Introduction
- History
- Approaches
- Methods and tools
Introduction
Neuropsychology is a sub-discipline of psychology. It is concerned with the relationship between a person's cognition and behaviour and the brain and the rest of the nervous system. This branch of psychology frequently focuses on how brain injuries or illnesses affect cognitive and behavioural functions. It is both an experimental and clinical field of psychology, aiming to understand how brain function influences behaviour and cognition and concerned with the diagnosis and treatment of neurological disorders' behavioural and cognitive effects. Whereas classical neurology focuses on nervous system pathology and classical psychology is largely divorced from it, neuropsychology studies neurological patients to discover how the brain correlates with the mind. Thus, it has concepts and concerns in common with neuropsychiatry and behavioural neurology in general. Lesion studies in humans and animals have been referred to as neuropsychology. It's also been used to record electrical activity from individual cells (or groups of cells) in higher primates (including some studies of human patients)
Neuropsychologists typically work in research settings (universities, laboratories, or research institutions), clinical settings (medical hospitals or rehabilitation settings, where they are frequently involved in assessing or treating patients with neuropsychological problems), forensic settings, or industry (often as clinical-trial consultants where CNS function is a concern).
History
Within the field of psychology, neuropsychology is a relatively new discipline. Fundamentals of Human Neuropsychology, the first textbook defining the field, was first published in 1980 by Kolb and Whishaw. However, its history can be traced back to the Third Dynasty in ancient Egypt, possibly even earlier. There is much debate about when societies began to consider the functions of various organs. For many centuries, the brain was thought to be useless and was frequently discarded during burials and autopsies. As medical science gained a better understanding of human anatomy and physiology, various theories about why the body functioned the way it did emerged. Bodily functions were frequently approached from a religious standpoint, and abnormalities were blamed on bad spirits and the gods. The brain has not always been regarded as the functional centre of the body. It has taken hundreds of years for us to gain a better understanding of the brain and how it influences our behaviour.
Ancient Egypt
Writings on medicine in ancient Egypt date back to the time of the priest Imhotep. They took a more scientific approach to medicine and disease, describing the brain, trauma, abnormalities, and treatments for future physicians to use as a reference. Despite this, Egyptians considered the heart, rather than the brain, to be the seat of the soul.
Aristotle
This emphasis on the heart, which originated in Egypt, was reinforced by Aristotle. He believed the heart was in charge of mental processes and saw the brain as a mechanism for cooling the heat generated by the heart due to its inert nature. He drew his conclusions from empirical research on animals. He discovered that, while their brains were cold to the touch and did not cause any movements, their hearts were warm and active, accelerating and slowing depending on mood. Such beliefs were held by many for many years, lasting through the Middle Ages and the Renaissance period until they began to falter in the 17th century as a result of additional research. The influence of Aristotle on the development of neuropsychology can be seen in modern-day language, as we "follow our hearts" and "learn by the heart."
Hippocrates
Hippocrates considered the brain to be the soul's seat. He made a link between the brain and bodily behaviours, writing, "The brain exercises the greatest power in man." Apart from shifting the emphasis from the heart to the brain as the "seat of the soul," Hippocrates did not go into much detail about its actual functioning. However, by refocusing the medical community's attention on the brain, his theory led to more scientific discovery of the organ responsible for our behaviours. Scientists were inspired to investigate the functions of the body and to find concrete explanations for both normal and abnormal behaviour for many years to come. They came to believe that there were natural and organically occurring reasons to explain various functions of the body, and that it could all be traced back to the brain as a result of scientific discovery. Hippocrates popularised the concept of the mind, which was widely regarded as a distinct function distinct from the actual brain organ.
René Descartes
René Descartes, a philosopher best known for his work on the mindbody problem, expanded on this idea. Descartes' ideas were frequently regarded as overly philosophical and lacking in sufficient scientific foundation. Descartes devoted much of his anatomical research to the brain, with a special emphasis on the pineal gland, which he claimed was the true "seat of the soul." The body was said to be mortal, and the soul immortal, while the body was still deeply rooted in a spiritual outlook toward the scientific world. The pineal gland was thought to be the exact location where the mind would interact with the mortal and machine-like body at the time. Descartes was convinced at the time that the mind had control over the behaviours of the body (controlling the person), but also that the body could have influence over the mind, which is known as dualism. This notion that the mind essentially had control over the body, but the body could resist or even influence other behaviours, was a major shift in how many physiologists viewed the brain. The mind's capabilities were observed to do much more than simply react, but also to be rational and function in organised, thoughtful ways – far more complex than he imagined the animal world to be. Although many dismissed and dismissed these ideas for years, they 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 truly were, and the total effects it had on daily life, as well as which treatments would be the most beneficial to helping those living with a dysfunctional mind. René Descartes's mind-body problem continues to this day, with many philosophical arguments both for and against his ideas. Regardless of how contentious they were and continue to be, Descartes's fresh and well-thought-out perspective has had long-lasting effects on the various disciplines of medicine, psychology, and much more, particularly in emphasising the separation of the mind from the body in order to explain observable behaviours.
Thomas Willis
Another significant contributor to the field of neuropsychology emerged in the mid-17th century. Thomas Willis attended Oxford University and studied the brain and behaviour from a physiological standpoint. Willis was the first to use the terms 'hemisphere' and 'lobe' to describe the brain. He was among the first to use the terms 'neurology' and 'psychology.' Willis examined specialised brain structures to refute the notion that humans were the only beings capable of rational thought. He hypothesised that higher structures were in charge of complex functions, whereas lower structures were in charge of functions similar to those seen in other animals, primarily reactions and automatic responses. He was especially interested in people suffering from manic depression and hysteria. His research was among the first to bring psychiatry and neurology together to study individuals. Willis concluded from his extensive study of the brain and behaviour that automated responses such as breathing, heartbeats, and other various motor activities were carried out in the lower region of the brain. Although much of his work has become obsolete, his ideas presented the brain as more complex than previously imagined, and paved the way for future pioneers to understand and build on his theories, particularly when it came to looking at brain disorders and dysfunctions.
Franz Joseph Gall
Franz Joseph Gall, a neuroanatomist and physiologist, made significant contributions to our understanding of the brain. He proposed that personality was directly related to brain features and structures. Gall's major contribution to the field of neuroscience, however, is the invention of phrenology. This new discipline regarded the brain as a mental organ, with the shape of the skull ultimately determining one's intelligence and personality. This theory, like many others that circulated at the time, took into account physical features of the face and body, head size, anatomical structure, and levels of intelligence; only Gall focused on the brain. However, there was much debate about the validity of Gall's claims because he was frequently found to be incorrect in his predictions.His research was among the first to bring psychiatry and neurology together to study individuals. Willis concluded from his extensive study of the brain and behaviour that automated responses such as breathing, heartbeats, and other various motor activities were carried out in the lower region of the brain. Although much of his work has become obsolete, his ideas presented the brain as more complex than previously imagined, and paved the way for future pioneers to understand and build on his theories, particularly when it came to looking at brain disorders and dysfunctions.
Jean-Baptiste Bouillaud
As science and medicine advanced in the late nineteenth century, the belief that the size of one's skull could determine one's level of intelligence faded. Jean-Baptiste Bouillaud, a physician, expanded on Gall's ideas and looked more closely at the concept of distinct cortical regions of the brain, each with their own independent function. Bouillaud was particularly interested in speech and published numerous papers on the anterior region of the brain being responsible for carrying out the act of speaking, a discovery that stemmed from Gall's research. He was also among the first to use larger samples for research, though it took many years for that method to become widely accepted. Bouillaud discovered that speech is completed and understood through different areas of the brain after studying over a hundred different case studies. His theory was strengthened by observing people with brain damage. Bouillaud, along with many other pioneers of the time, made significant advances in the field of neurology, particularly in the localization of function. There are many debatable debates about who deserves the most credit for such discoveries, and many people go unmentioned, but Paul Broca is perhaps one of the most famous and well-known contributors to neuropsychology – often referred to as the discipline's "father."
Paul Broca
Paul Broca devoted much of his research to the phenomenon of how speech is understood and produced, inspired by advances in the field of localised function within the brain. It was discovered and expanded upon through his research that we communicate via the left hemisphere. Broca's observations and methods are widely regarded as the point at which neuropsychology truly takes shape as a distinct and respected discipline. With the knowledge that specific, independent areas of the brain are responsible for speech articulation and comprehension, the brain's abilities were finally being recognised as the complex and highly intricate organ that it is. Broca was essentially the first person to fully depart from phrenological ideas and delve deeper into a more scientific and psychological view of the brain.
Karl Spencer Lashley
The following works and theories by Lashley are summarised in his book Brain Mechanisms and Intelligence. Much of Lashley's research was motivated by his theory of the Engram. An engram was thought to be a part of the brain that stored a specific memory. He continued to use the training/ablation method taught to him by Franz. He'd teach a rat a maze, then use systematic lesions and removed sections of cortical tissue to see if the rat forgot what it'd learned. He discovered that forgetting was determined by the amount of tissue removed rather than the location of the tissue removal through his research with rats. He referred to this as mass action, and he believed that it was a general rule that governed how brain tissue would respond regardless of the type of learning. However, we now know that mass action was a misinterpretation of his empirical results, because the rats needed multiple cortical areas to run a maze. Cutting into small individual parts does not significantly impair the rats' brains, but taking large sections removes multiple cortical areas at once, affecting various functions such as sight, motor coordination, and memory, rendering the animal unable to run a maze properly. Lashley also proposed that a portion of a functional area can perform the function of the entire area even if the rest of the area is removed. He referred to this phenomenon as equipotentiality. We now know that he was seeing evidence of brain plasticity: within certain constraints, the brain has the ability for certain areas to take over the functions of other areas if those areas fail or are removed - though not to the extent that Lashley initially argued.
Approaches
Experimental neuropsychology is a method that uses experimental psychology methods to investigate the relationship between the nervous system and cognitive function. Although a minority of researchers may conduct animal experiments, the majority of their work involves studying healthy humans in a laboratory setting. To make links between neuroanatomy and psychological function, human work in this area frequently takes advantage of specific features of our nervous system (for example, visual information presented to a specific visual field is preferentially processed by the cortical hemisphere on the opposite side).
Clinical neuropsychology is the application of neuropsychological knowledge to the evaluation (see neuropsychological test and neuropsychological assessment), management, and rehabilitation of people who have suffered illness or injury (especially to the brain) that has resulted in neurocognitive problems. They bring a psychological perspective to treatment in particular, in order to understand how such illness and injury may affect and be affected by psychological factors. They can also provide an opinion on whether a person's difficulties are the result of brain pathology, an emotional or other (potentially) reversible cause, or both. A test, for example, might reveal that both patients X and Y are unable to name items they have previously been exposed to within the last 20 minutes (indicating possible dementia). If patient Y can name some of them after further prompting (e.g., being told that the item they couldn't name is a fruit), this allows for a more specific diagnosis than simply dementia (Y appears to have the vascular type which is due to brain pathology but is usually at least somewhat reversible). Clinical neuropsychologists frequently work in hospital settings as part of an interdisciplinary medical team; others work in private practise and may provide expert testimony in medico-legal cases.
Cognitive neuropsychology is a relatively new field that emerged as a synthesis of the complementary approaches of experimental and clinical neuropsychology. It studies people who have suffered from brain injury or neurological illness in order to better understand the mind and brain. Functional localization is a model of neuropsychological functioning. This is based on the principle that if a specific cognitive problem can be identified following an injury to a specific area of the brain, it is possible that this part of the brain is involved in some way. However, there is reason to believe that the relationship between mental functions and neural regions is not as simple as it appears. An alternative model of the mind-brain connection, such as parallel processing, may be more explanatory of the human brain's workings and dysfunction. Another approach looks at how the pattern of errors produced by brain-damaged people can limit our understanding of mental representations and processes without referring to the underlying neural structure. Cognitive neuropsychiatry, a more recent but related approach, seeks to understand the normal function of the mind and brain by studying psychiatric or mental illness.
Connectionism is the use of artificial neural networks to model specific cognitive processes using simplified but plausible models of how neurons work. Once trained to perform a specific cognitive task, these networks are frequently damaged or 'lesioned' in an attempt to understand and compare the results to the effects of brain injury in humans.
Functional neuroimaging employs specific neuroimaging technologies to obtain brain readings, usually while a person is performing a specific task, in an attempt to understand how the activation of specific brain areas is related to the task. The expansion of methodologies for using cognitive testing within established functional magnetic resonance imaging (fMRI) techniques to study brain-behavior relationships, in particular, is having a significant impact on neuropsychological research.
In practise, these approaches are not mutually exclusive, and most neuropsychologists choose the best approach or approaches to complete the task at hand.
Methods and tools
Standardized neuropsychological tests
These tasks have been designed in such a way that task performance can be linked to specific neurocognitive processes. These tests are usually standardised, which means that they have been given to a specific group (or groups) of people before being used in individual clinical cases. The data produced as a result of standardisation is referred to as normative data. Following the collection and analysis of these data, they are used as the comparative standard against which individual performances can be compared. The Wechsler Memory Scale (WMS), the Wechsler Adult Intelligence Scale (WAIS), the Boston Naming Test, the Wisconsin Card Sorting Test, the Benton Visual Retention Test, and the Controlled Oral Word Association are all neuropsychological tests.
Brain scans
Brain scans are commonly used to investigate the structure or function of the brain, either as a means of better assessing brain injury with high resolution images or by examining the relative activations of different brain areas. These technologies may include fMRI (functional magnetic resonance imaging) and positron emission tomography (PET), which produce data on function, as well as MRI (magnetic resonance imaging) and computed axial tomography (CAT or CT), which produce structural data.
Global Brain Project
Brain models based on mice and monkeys have been developed based on theoretical neuroscience involving working memory and attention, while mapping brain activity based on time constants validated by neuronal activity measurements in various layers of the brain. These methods also correspond to decision states of behaviour in simple tasks with binary outcomes.
Electrophysiology
The application of electrophysiological measures to assess brain activation by measuring the electrical or magnetic field produced by the nervous system. Electroencephalography (EEG) or magnetoencephalography (MEG) may be used (MEG).
Experimental tasks
The use of designed experimental tasks, often controlled by computer, to measure reaction time and accuracy on specific tasks thought to be related to a specific neurocognitive process. The Cambridge Neuropsychological Test Automated Battery (CANTAB) or CNS Vital Signs are two examples (CNSVS).
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