Cognitive neuropsychology

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Cognitive neuropsychology is a branch of cognitive psychology that aims to understand how the structure and function of the brain relates to specific psychological processes. Cognitive psychology is the science that looks at how mental processes are responsible for our cognitive abilities to store and produce new memories, produce language, recognize people and objects, as well as our ability to reason and problem solve. Cognitive neuropsychology places a particular emphasis on studying the cognitive effects of brain injury or neurological illness with a view to inferring models of normal cognitive functioning. Evidence is based on case studies of individual brain damaged patients who show deficits in brain areas and from patients who exhibit double dissociations. Double dissociations involve two patients and two tasks. One patient is impaired at one task but normal on the other, while the other patient is normal on the first task and impaired on the other. For example, patient A would be poor at reading printed words while still being normal at understanding spoken words, while the patient B would be normal at understanding written words and be poor at understanding spoken words. Scientists can interpret this information to explain how there is a single cognitive module for word comprehension. From studies like these, researchers infer that different areas of the brain are highly specialised. Cognitive neuropsychology can be distinguished from cognitive neuroscience, which is also interested in brain damaged patients, but is particularly focused on uncovering the neural mechanisms underlying cognitive processes. [1]

Contents

History

"Front and lateral view of the cranium, representing the direction in which the iron traversed its cavity..." Phineas gage - 1868 skull diagram.jpg
"Front and lateral view of the cranium, representing the direction in which the iron traversed its cavity..."

Cognitive neuropsychology has its roots in the diagram making approach to language disorder that started in the second half of the 19th century. The discovery that aphasia took different forms depending on the location of brain damage provided a powerful framework for understanding brain function. [3]

In 1861 Paul Broca, reported a post mortem study of an aphasic patient who was speechless apart from a single nonsense word: "Tan". Broca showed that an area of the left frontal lobe was damaged. As Tan was unable to produce speech but could still understand it, Broca argued that this area might be specialised for speech production and that language skills might be localized to this cortical area. Broca did a similar study on another patient, Lelong, a few weeks later. Lelong, like Tan, could understand speech but could only repeat the same 5 words. After examining his brain, Broca noticed that Lelong had a lesion in approximately the same area as his patient Tan. He also noticed that in the more than 25 patients he examined with aphasia, they all had lesions to the left frontal lobe but there was no damage to the right hemisphere of the brain. From this he concluded that the function of speech was probably localized in the inferior frontal gyrus of the left hemisphere of the brain, an area now known as Broca's area.

Karl Wernicke subsequently reported patients with damage further back in the temporal lobe who could speak but were unable to understand what was said to them, providing evidence for two potentially interconnected language centres. These clinical descriptions were integrated into a theory of language organisation by Lichtheim. [4] Subsequently, these models were used and developed to inform Dejerine's account of reading, Liepmann's theory of action and Lissauer's 1890 account of object recognition and Lewandowsky and Stadelmann's 1908 account of calculation.

Broca's area and Wernicke's area. BrocasAreaSmall.png
Broca's area and Wernicke's area.

However, the early 20th century saw a reaction to the overly-precise accounts of the diagram making neurologists. Pierre Marie challenged conclusions against previous evidence of Broca's areas in 1906 and Henry Head attacked the whole field of cerebral localisation 1926.

The modern science of cognitive neuropsychology emerged during the 1960s stimulated by the insights of the neurologist Norman Geschwind who demonstrated that the insights of Broca and Wernicke were still clinically relevant. The other stimulus to the discipline was the "Cognitive Revolution" and the growing science of cognitive psychology which had emerged as a reaction to behaviorism in the mid 20th century. [5] Psychologists in the mid-1950s acknowledged that the structure of mental information-processing systems could be investigated in scientifically acceptable ways. They developed and applied new cognitive processing models to explain experimental data from not only studies of speech and language but also those of selective attention. [6] Cognitive psychologists and clinical neuropsychologists developed more research collaborations to gain a better understanding of these disorders. The rebirth of neuropsychology was marked by the publishing of two seminal collaborative papers from Marshall & Newcombe (1966) on reading and Warrington & Shallice (1969) on memory. [6] Subsequently, work by pioneers such as Elizabeth Warrington, Brenda Milner, Tim Shallice, Alan Baddeley and Lawrence Weiskrantz demonstrated that neurological patients were an important source of data for cognitive psychologists.

It took less than one decade for neuropsychology to be fully re-established. More achievements in neuropsychology were recognized: the establishment of the first major book discussing neuropsychology using a cognitive approach, Deep Dyslexia, in 1980 after a scientific meeting about the topic in Oxford in 1977, the birth of the Cognitive Neuropsychology journal in 1984, and the publishing of the first textbook of neuropsychology, Human Cognitive Neuropsychology in 1988. [6]

A particular area of interest was memory. Patients with amnesia caused by injuries to the hippocampus in the temporal cortex and midbrain areas (especially the mamillary bodies) were of early interest. A patient with severe case of amnesia will not be able to remember meeting the examiner if they leave the room and return, let alone events of the previous day (episodic memory), but they will still be able to learn how to tie their shoes (procedural memory), remember a series of numbers for a few seconds (short term memory or working memory) and be able to recall historical events they have learned in school (semantic memory). By contrast, patients may lose their short term memory abilities while retaining their long term memory functions. Many other studies like this have been done in the field of neuropsychology examining lesions and the effect they have on certain areas of the brain and their functions.

Most of Molaison's hippocampus was removed bilaterally. Hippolobes.gif
Most of Molaison's hippocampus was removed bilaterally.

Studies on the amnesic patient Henry Molaison, formerly known as patient H.M., are commonly cited as some of the precursors, if not the beginning of modern cognitive neuropsychology. Molaison had parts of his medial temporal lobes surgically removed to treat intractable epilepsy in 1953. Much of the hippocampus was also removed along with the medial temporal lobes. The treatment proved successful in reducing his dangerous seizures, but left him with a profound but selective amnesia. After the surgery, Molaison was able to remember some big events from before the surgery, such as the stock market crash in 1929, but was confused about many others and could no longer form new memories. This accidental experiment showed scientists how the brain processes different types of memory. Because Molaison's impairment was caused by surgery, the damaged parts of his brain were known, information which was usually not knowable in a time before accurate neuroimaging became widespread. Scientists concluded that while the hippocampus is needed in the creation of new memories, it is not needed in the retrieval of old ones; they are two separate processes. They also realized that the hippocampus and the medial temporal lobes, both of the areas removed from Molaison, are the areas responsible for converting short term memory to long term memory.

Much of the early work of cognitive neuropsychology was carried out with limited reference to the detailed localisation of brain pathology. Neuroimaging was relatively imprecise and other anatomically based techniques were also limited. The emphasis of many researchers as late as 1990 was on the analysis of patterns of cognitive deficit rather than on where the injury was located. [7] Despite the lack of detailed anatomical data, studies of reading, language and memory had a number of important implications. The first is that certain cognitive processes (such as language) could be damaged separately from others, and so might be handled by distinct and independent cognitive (and neural) processes. (For more on the cognitive neuropsychological approach to language, see Eleanor Saffran, among others.) The second is that such processes might be localized to specific areas of the brain. Whilst both of these claims are still controversial to some degree, the influence led to a focus on brain injury as a potentially fruitful way of understanding the relationship between psychology and neuroscience.

Methods

A key approach within cognitive neuropsychology has been to use single case studies and dissociation as a means of testing theories of cognitive function. For example, if a theory states that reading and writing are simply different skills stemming from a single cognitive process, it should not be possible to find a person who, after brain injury, can write but not read or read but not write. This selective breakdown in skills suggests that different parts of the brain are specialized for the different processes and so the cognitive systems are separable.

The philosopher Jerry Fodor has been particularly influential in cognitive neuropsychology, particularly with the idea that the mind, or at least certain parts of it, may be organised into independent modules. Evidence that cognitive skills may be damaged independently seem to support this theory to some degree, although it is clear that some aspects of mind (such as belief for example) are unlikely to be modular. Fodor, a strict functionalist, rejects the idea that the neurological properties of the brain have any bearing on its cognitive properties and doubts the whole discipline of cognitive neuropsychology.

With improved neuroimaging techniques, it has been possible to correlate patterns of impairment with a knowledge of exactly which parts of the nervous system are damaged, allowing previously undiscovered functional relationships to be explored (the lesion method). Contemporary cognitive neuropsychology uses many of the same techniques and technologies from the wider science of neuropsychology and fields such as cognitive neuroscience. These may include neuroimaging, electrophysiology and neuropsychological tests to measure either brain function or psychological performance. Useful technology in cognitive neuropsychology includes positron-emission tomography (PET) and functional magnetic resonance imaging (fMRI). These techniques make it possible to identify the areas of the brain responsible for performing certain cognitive tasks by measuring blood flow in the brain. PET scans sense the low-level radiation in the brain and produce 3-D images, whereas an fMRI works on a magnetic signal and is used to “map the brain”. Electroencephalography (EEG) records the brain’s electrical activity and can identify changes that occur over milliseconds. EEG is often used in patients with epilepsy to detect seizure activity.

The principles of cognitive neuropsychology have recently been applied to mental illness, with a view to understanding, for example, what the study of delusions may tell us about the function of normal belief. This relatively young field is known as cognitive neuropsychiatry.

See also

Related Research Articles

<span class="mw-page-title-main">Language center</span> Speech processing in the brain

In neuroscience and psychology, the term language center refers collectively to the areas of the brain which serve a particular function for speech processing and production. Language is a core system, which gives humans the capacity to solve difficult problems and provides them with a unique type of social interaction. Language allows individuals to attribute symbols to specific concepts and display them through sentences and phrases that follow proper grammatical rules. Moreover, speech is the mechanism in which language is orally expressed.

<span class="mw-page-title-main">Broca's area</span> Speech production region in the dominant hemisphere of the hominid brain

Broca's area, or the Broca area, is a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions linked to speech production.

<span class="mw-page-title-main">Cognitive neuroscience</span> Scientific field

Cognitive neuroscience is the scientific field that is concerned with the study of the biological processes and aspects that underlie cognition, with a specific focus on the neural connections in the brain which are involved in mental processes. It addresses the questions of how cognitive activities are affected or controlled by neural circuits in the brain. Cognitive neuroscience is a branch of both neuroscience and psychology, overlapping with disciplines such as behavioral neuroscience, cognitive psychology, physiological psychology and affective neuroscience. Cognitive neuroscience relies upon theories in cognitive science coupled with evidence from neurobiology, and computational modeling.

<span class="mw-page-title-main">Neuropsychology</span> Study of the brain related to specific psychological processes and behaviors

Neuropsychology is a branch of psychology concerned with how a person's cognition and behavior are related to the brain and the rest of the nervous system. Professionals in this branch of psychology often focus on how injuries or illnesses of the brain affect cognitive and behavioral functions.

<span class="mw-page-title-main">Henry Molaison</span> American memory disorder patient

Henry Gustav Molaison, known widely as H.M., was an American who had a bilateral medial temporal lobectomy to surgically resect the anterior two thirds of his hippocampi, parahippocampal cortices, entorhinal cortices, piriform cortices, and amygdalae in an attempt to cure his epilepsy. Although the surgery was partially successful in controlling his epilepsy, a severe side effect was that he became unable to form new memories.

<span class="mw-page-title-main">Temporal lobe</span> One of the four lobes of the mammalian brain

The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain.

<span class="mw-page-title-main">Brenda Milner</span> British-Canadian neuroscientist and neuropsychologist

Brenda Milner is a British-Canadian neuropsychologist who has contributed extensively to the research literature on various topics in the field of clinical neuropsychology. Milner is a professor in the Department of Neurology and Neurosurgery at McGill University and a professor of Psychology at the Montreal Neurological Institute. As of 2020, she holds more than 25 honorary degrees and she continued to work in her nineties. Her current work covers many aspects of neuropsychology including her lifelong interest in the involvement of the temporal lobes in episodic memory. She is sometimes referred to as the founder of neuropsychology and has been essential in its development. She received the Balzan Prize for Cognitive Neuroscience in 2009, and the Kavli Prize in Neuroscience, together with John O'Keefe, and Marcus E. Raichle, in 2014. She turned 100 in July 2018 and at the time was still overseeing the work of researchers.

In neurology, retrograde amnesia (RA) is a loss of memory-access to events that occurred or information that was learned in the past. It is caused by an injury or the onset of a disease. It tends to negatively affect episodic, autobiographical, and declarative memory, while keeping procedural memory intact without increasing difficulty for learning new information. RA can be temporally graded, or more permanent based on the severity of its cause. It is usually consistent with Ribot's law. The law states that subjects are more likely to lose memories closer to the traumatic incident than more memories that happened further from the incident. The type of information that is forgotten can range from a specific memory, such as a single event, or a more general memory. This would resemble generic amnesia. Anterograde amnesia is a similar condition that deals with the inability to form new memories following the onset of an injury or disease.

Explicit memory is one of the two main types of long-term human memory, the other of which is implicit memory. Explicit memory is the conscious, intentional recollection of factual information, previous experiences, and concepts. This type of memory is dependent upon three processes: acquisition, consolidation, and retrieval. Explicit memory can be divided into two categories: episodic memory, which stores specific personal experiences, and semantic memory, which stores factual information. Explicit memory requires gradual learning, with multiple presentations of a stimulus and response.

<span class="mw-page-title-main">Comparative neuropsychology</span>

Comparative neuropsychology refers to an approach used for understanding human brain functions. It involves the direct evaluation of clinical neurological populations by employing experimental methods originally developed for use with nonhuman animals.

<span class="mw-page-title-main">Lateralization of brain function</span> Specialization of some cognitive functions in one side of the brain

The lateralization of brain function is the tendency for some neural functions or cognitive processes to be specialized to one side of the brain or the other. The median longitudinal fissure separates the human brain into two distinct cerebral hemispheres, connected by the corpus callosum. Although the macrostructure of the two hemispheres appears to be almost identical, different composition of neuronal networks allows for specialized function that is different in each hemisphere.

<span class="mw-page-title-main">Executive functions</span> Cognitive processes necessary for control of behavior

In cognitive science and neuropsychology, executive functions are a set of cognitive processes that are necessary for the cognitive control of behavior: selecting and successfully monitoring behaviors that facilitate the attainment of chosen goals. Executive functions include basic cognitive processes such as attentional control, cognitive inhibition, inhibitory control, working memory, and cognitive flexibility. Higher-order executive functions require the simultaneous use of multiple basic executive functions and include planning and fluid intelligence.

<span class="mw-page-title-main">Inferior temporal gyrus</span> One of three gyri of the temporal lobe of the brain

The inferior temporal gyrus is one of three gyri of the temporal lobe and is located below the middle temporal gyrus, connected behind with the inferior occipital gyrus; it also extends around the infero-lateral border on to the inferior surface of the temporal lobe, where it is limited by the inferior sulcus. This region is one of the higher levels of the ventral stream of visual processing, associated with the representation of objects, places, faces, and colors. It may also be involved in face perception, and in the recognition of numbers and words.

<span class="mw-page-title-main">Dissociation (neuropsychology)</span>

In neuropsychology, dissociation involves identifying the neural substrate of a particular brain function through identification of case studies, neuroimaging, or neuropsychological testing.

<span class="mw-page-title-main">Brain asymmetry</span> Term in human neuroanatomy referring to several things

In human neuroanatomy, brain asymmetry can refer to at least two quite distinct findings:

Retrospective memory is the memory of people, words, and events encountered or experienced in the past. It includes all other types of memory including episodic, semantic and procedural. It can be either implicit or explicit. In contrast, prospective memory involves remembering something or remembering to do something after a delay, such as buying groceries on the way home from work. However, it is very closely linked to retrospective memory, since certain aspects of retrospective memory are required for prospective memory.

The neuroanatomy of memory encompasses a wide variety of anatomical structures in the brain.

<span class="mw-page-title-main">Amnesia</span> Cognitive disorder where memory is disturbed or lost

Amnesia is a deficit in memory caused by brain damage or disease, but it can also be caused temporarily by the use of various sedatives and hypnotic drugs. The memory can be either wholly or partially lost due to the extent of damage that was caused. There are two main types of amnesia: retrograde amnesia and anterograde amnesia. Retrograde amnesia is the inability to retrieve information that was acquired before a particular date, usually the date of an accident or operation. In some cases the memory loss can extend back decades, while in others the person may lose only a few months of memory. Anterograde amnesia is the inability to transfer new information from the short-term store into the long-term store. People with anterograde amnesia cannot remember things for long periods of time. These two types are not mutually exclusive; both can occur simultaneously.

Executive functions are a cognitive apparatus that controls and manages cognitive processes. Norman and Shallice (1980) proposed a model on executive functioning of attentional control that specifies how thought and action schemata become activated or suppressed for routine and non-routine circumstances. Schemas, or scripts, specify an individual's series of actions or thoughts under the influence of environmental conditions. Every stimulus condition turns on the activation of a response or schema. The initiation of appropriate schema under routine, well-learned situations is monitored by contention scheduling which laterally inhibits competing schemas for the control of cognitive apparatus. Under unique, non-routine procedures controls schema activation. The SAS is an executive monitoring system that oversees and controls contention scheduling by influencing schema activation probabilities and allowing for general strategies to be applied to novel problems or situations during automatic attentional processes.

Nina Dronkers is an American cognitive neuroscientist. She is known for her studies of aphasia and their application for understanding brain systems involved in normal language abilities. She is a professor in the Psychology Department at the University of California, Berkeley, and a faculty member of the Helen Wills Neuroscience Institute. She is also an Emerita Research Career Scientist of the Veterans Administration Northern California Health Care System where she established the Center for Aphasia and Related Disorders. She serves as a consultant for the Memory and Aging Center at UCSF Medical Center. In addition, she is an adjunct professor in the Department of Neurology, University of California, Davis, School of Medicine. She has published over 120 scientific papers and is the co-author with Lise Menn of a textbook: Psycholinguistics: Introduction and Applications, Second edition.

References

  1. Schacter, Daniel L. (2000). "Understanding Implicit memory: A cognitive neuroscience approach". In Gazzaniga, M.S. (ed.). Cognitive Neuroscience: A Reader. Wiley. ISBN   978-0-631-21659-9. The term cognitive neuropsychology often connotes a purely functional approach to patients with cognitive deficits that does not make use of, or encourage interest in, evidence and ideas about brain systems and processes
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  3. Coltheart, Max (2008). "Cognitive neuropsychology". Scholarpedia. 3 (2): 3644. Bibcode:2008SchpJ...3.3644C. doi: 10.4249/scholarpedia.3644 . ISSN   1941-6016.
  4. Carlson, Neil R. (2013). Physiology of Behavior. NJ, U.S: Pearson Education, Inc., p. 132.
  5. Miller, G. A. (2003). The cognitive revolution: a historical perspective. Trends in Cognitive Sciences, 7(3), 141-144. doi: 10.1016/s1364-6613(03)00029-9.
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  7. Shallice, Tim (October 2009). From Neuropsychology to Mental Structure. Cambridge University Press. ISBN   9780511526817.

Further reading