Functions of the Cerebral Cortex

10 Key excerpts on "Functions of the Cerebral Cortex"

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  Neuropsychology

  A Textbook of Systems and Psychological Functions of the Human Brain

  • Stuart J. Dimond(Author)
  • 2013(Publication Date)
  • Butterworth-Heinemann

    (Publisher)

  According to this analysis, the mental world of man is divided up by the separateness of the mid-brain mechanisms into four realms of action: the intellect, emotion, motor functions, and sex and sleep. Each, with the exception of sleep, shares a massive cortical component, but each devolves upon a separate structure at the mid-brain region, and it is this which leads to the view that these are the four pillars of the mind given because the brain is constructed in the way that it is. The Cortex That vast confusing web of tissue that we call the cortex appears at first sight to defy description. The range of its functions is enormous and the complexity of its organization intricate, and yet there is a basic order in the cortex both in terms of the way in which functions are arranged and mapped on to the cortex and also in terms of the way in which the business of the cortex is conducted in order to fulfil these essential functions. The cortex is not a chaotic structure and there is a discernible order to it, as is apparent from the work described in this volume. We have argued previously that if we adopt an internal perspective for the functions of the brain, and we take a brain's eye view of its function rather than that, say, of the neurosurgeon who views the brain from without, then we come to a different interpretation not only of the respective functions of the internal parts, but also of the way in which they relate to the cortex itself. If we imagine ourselves to be an observer standing at some central important pivotal point in the brain and looking through the structures to the periphery bounded by the cranial wall, then the structures of the cortex form the distant extent of our vision. They are the furthest, most distant envelope, but envelope they are, containing and restricting the structures within. Essentially, therefore, the cortex forms the external lining for the brain.

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  Central Nervous System Tumours of Childhood

  • Eddy Estlin, Stephen Lowis(Authors)
  • 2005(Publication Date)
  • Mac Keith Press

    (Publisher)

  21 AN OVERVIEW OF CEREBRAL FUNCTIONING AND ITS APPLICATION IN THE DEVELOPING BRAIN Andrew Curran This chapter aims to provide a readily understandable overview of the mechanisms of how basic functions, such as memory and the emotional content of thoughts, are now believed to work. The aim is to build a picture of brain functioning that allows the reader to place a tumour in any position in the brain and be able to have some idea of the impact that the tumour, surgical removal and radiotherapy will have on cognitive and emotional functions. The first part outlines normal functioning of the brain, with particular reference to the key anatomical structures central to this functionality. Part two describes how structures in the developing brain gradually mature to integrate emotional perception into our memories. The penultimate section focuses on the effects of stress on the developing brain and reinforces the need for sensitive handling of children undergoing stressful experiences. The final section looks at the hemispheric lateralization of functionality. In all fields of medicine, but especially in the care of children, the understanding of how the brain works, and especially the importance of emotional health in allowing the individual to achieve their maximal potential must, I believe, always be paramount in our thoughts. The normal brain T HE R EPTILIAN B RAIN The control of sophisticated structures, such as the bodies of multicellular living organisms, requires coordination and control beyond that seen in simpler organisms. A unified ‘master control system’ to govern these activities in lesser systems is provided by the spinal cord, brainstem and corpus striatum (Fig. 21.1), the so-called reptilian brain, in higher organisms. MacLean (1990) has described this as the first step towards the “triune brain”, the ultimate expression of which is seen in modern man.

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  Functional and Clinical Neuroanatomy

  A Guide for Health Care Professionals

  • Jahangir Moini, Pirouz Piran(Authors)
  • 2020(Publication Date)
  • Academic Press

    (Publisher)

  Chapter 6

  Cerebral cortex

  Abstract

  The cerebral cortex is a layer of neurons and synapses (gray matter) on the surface of the cerebral hemispheres. This is folded into gyri, and about two-thirds of the cortex's area is buried inside fissures. The cerebral cortex integrates higher mental functions, general movements, functions of the viscera, perceptions, and behavioral reactions. It has many different classifications. The cerebral cortex has 47 separate function areas, with differing cellular designs.

  Keywords

  Cerebrum; Gross anatomy; Cerebral cortex; Neocortex; Electroencephalogram; Split-brain syndrome

  The cerebral cortex is a layer of neurons and synapses (gray matter) on the surface of the cerebral hemispheres. This is folded into gyri, and about two-thirds of the cortex's area is buried inside fissures. The cerebral cortex integrates higher mental functions, general movements, functions of the viscera, perceptions, and behavioral reactions. It has many different classifications. The cerebral cortex has 47 separate function areas, with differing cellular designs.

  Stimulation of the precentral cortex or motor area, using electrodes, causes contractions of the voluntary muscles. If the motor speech area in the inferior frontal gyrus is destroyed, this causes motor aphasia or speech defects, even though the vocal organs are healthy and intact. If the brain cortex is stimulated as in case of a seizure, this stimulation will affect circulation, respiration, reactions of the pupils, and other visceral activities.

  Cerebrum

  The cerebrum is the largest and most obvious portion of the human brain. It forms from the embryonic structure called the telencephalon . The cerebrum is the center of voluntary motor control and complex mental processes.

  Gross anatomy

  The cerebrum is much larger than the other portions of the brain. It is divided into two cerebral hemispheres that are separated by the longitudinal fissure . A prominent tract of fibers called the corpus callosum also connects the hemispheres. Each hemisphere has conspicuous gyri , which appear as “wrinkles” that are separated by grooves known as sulci . The surface of the cerebrum folds into the gyri in a way that allows for a larger amount of cortex to fit inside the cranium and because of the gyri, the cerebrum has about 2500 cm2

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  The Brain

  An Introduction to Functional Neuroanatomy

  • Charles Watson, Matthew Kirkcaldie, George Paxinos(Authors)
  • 2010(Publication Date)
  • Academic Press

    (Publisher)

  These highly sophisticated areas, termed cortical association areas, make up the bulk of the human neocortex. Some clues to the function of the association areas are offered by the study of some people with cortical damage. These people may lose the ability to combine certain types of information, such as the ability to name objects or read maps, or they may have larger deficits such as a complete loss of color perception. In prefrontal regions, the result of damage may be subtle, such as small deficits in planning, organization, and concern for the future. There may also be inappropriate behavior in social settings. These types of deficits have taught neuroscientists and neuropsychologists a great deal about the processing abilities of the cortex, but we still lack any real understanding of how these abilities are generated.

  The cerebral cortex and behavior

  Much of the survival behavior in mammals does not primarily involve the cerebral cortex. Most basic behaviors and many learned movements take place with minimal cortical input. This is evident in experiments in which rats have had their cortex removed; the rats are still able to feed, drink, and avoid threats.

  However, damage to some cortical areas in humans can produce subtle but profound personality changes and behavioral problems. In the past it was popular to talk about ‘silent’ areas of cortex but it is now apparent that the function of these areas is simply too sophisticated to be measured in standard clinical situations. The cerebral cortex is extremely expensive to run in terms of metabolic energy, and its cells are in near-constant activity during awake behavior. Any animal with silent cortical regions would simply be wasting energy, endangering its survival.

  The main job of the cerebral cortex is to analyze, predict, and respond to environmental events.

  Alexander Luria and aphasia

  The brilliant Russian researcher Alexander Luria is credited with inventing the field of neuropsychology. During the Second World War he made a detailed study of the abilities of soldiers who had suffered small head injuries. His analysis is the foundation of modern theories on aphasia (the inability to communicate). The introduction of Armalite-style weaponry in recent years means that small wartime head injuries are now extremely rare, because a modern bullet flattens on impact to make much larger wounds. Because of cold-war politics, American scientists largely ignored Luria's extraordinary work until the 1970s.

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  Vision Facts

  Questions about the Human Eye

  • Jason Yang, Charles Pidgeon(Authors)
  • 2018(Publication Date)
  • Universal-Publishers

    (Publisher)

  great-grandmother cell hypothesis is a name for an early attempt to explain how the brain processes visual information. In this hypothesis, there is a neuron in the brain for every object that can be recognized, including one for your great-grandmother. However, this hypothesis has been refuted, as a neuron for every recognizable object means that the brain would have to be far larger than is realistic.

  Gross, C. G. “Genealogy of the ‘grandmother cell.’” Neuroscientist 8, no. 5 (October 2002): 512–18. Accessed September 21, 2017. https://www.ncbi.nlm.nih.gov/pubmed/12374433 .

  Q97	What is the cerebral cortex?

  A97

  The cerebral cortex (or “cortex”) is a layer of neurons two to four millimeters thick on the surface of the brain. It is composed closely packed neurons forming gray matter. The cerebral cortex consists of four lobes: the occipital, parietal, temporal, and frontal lobes. It is divided into the left and right cerebral hemispheres. Some main Functions of the Cerebral Cortex include perception, awareness, memory, consciousness, speech, and higher level thinking. “The Cerebral Cortex.” AP Psychology Community . Accessed September 14, 2017. http://www.appsychology.com/Book/Biological/cerebral_cortex.htm . The cerebral cortex consists of four lobes: the frontal lobe (red), parietal lobe (green), temporal lobe (blue), and occipital lobe (yellow).

  Q98	What is the function of each lobe of the cortex?

  A98

  Each lobe in the cortex serves unique roles. The frontal lobe is considered to be the control center for emotions and personality. It is also involved in problem solving, motor skills, judgement, and social behaviour. The parietal lobe processes information related to several senses, including taste, temperature, touch, as well as helping out with vision. The temporal lobe is primarily involved in hearing and language. However, parts of the temporal lobe are also dedicated to vision. Finally, the occipital lobe

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  A Textbook of Neuroanatomy

  • Maria A. Patestas, Leslie P. Gartner(Authors)
  • 2016(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  A 45-year-old woman, who was previously in perfect health, had two seizures in the past week. Both occurred suddenly and each lasted less than a minute. The first seizure started as twitching of the right side of the face, which progressed to twitching of her right hand and then her right leg. She felt some perioral numbness as well. There was no loss of consciousness or other symptoms, and she was aware of what had occurred. This happened while in bed. The second seizure, as described by her husband, started with facial twitching but she rapidly lost consciousness and then had a generalized convulsion. She bit her tongue and had blood in her mouth. She also had urinary incontinence. She began responding a few minutes after the convulsion, but she was still confused and somewhat agitated for about 30 minutes after that. She had never had a seizure before. In between these spells she had been normal and examination was normal.

  The cerebral cortex is the most complex component of the human brain, as a result of its complex and widespread connections. It functions in the planning and initiation of motor activity, perception and conscious awareness of sensory information, learning, cognition, comprehension, memory, conceptual thinking, and awareness of emotions.

  The cerebral cortex (L., cortex, “bark”) is a multilayered sheet of nerve cell bodies and associated cell processes that covers the paired and prominent cerebral hemispheres of the cerebrum, forming a superficial layer much like bark covers a tree. The majority of the cerebral cortex consists of phylogenetically the most highly evolved and complex neural tissue of the human brain.

  The central nervous system (CNS) is comprised of white and gray matter. White matter consists mostly of nerve cell axons, whereas gray matter consists mostly of nerve cell bodies. Gray matter is arranged into nuclei or cortex. Nuclei are aggregations of nerve cell bodies embedded deep within the cerebrum or in the spinal cord. The cerebral cortex consists of 50–100 billion nerve cell bodies arranged into a three- to six-layered sheet that laminates the brain surface.

  The cerebral cortex overlies the subcortical white matter of the cerebral hemispheres. In other animals, the brain's cortical surface appears smooth, whereas in humans the brain surface is convoluted displaying prominent, alternating grooves and elevations as a result of the folding of the cerebral cortex, which occurs during development. The elevations are referred to as gyri, whereas the grooves are referred to as sulci or fissures (Fig. 25.1 ). Sulci are shallow, short grooves, whereas fissures are deeper and more constant grooves, with a consistent location on the brain surface. The cortex forming the gyri dips down into the pit of the adjacent sulci or fissures to line them. Certain gyri, sulci, and fissures are similar in all normal human brains. Others, however, may vary in different brains and in the two cerebral hemispheres of the same brain. The gyri and sulci greatly increase the total surface area of the cerebral cortex. If the cerebral cortex of a normal human brain were spread out (that is, if the pleats formed by the sulci and fissures were stretched out), the cortex would extend over 0.23 m2 (2.5 ft2

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  Cognitive Neuroscience

  • Marie T. Banich, Rebecca J. Compton(Authors)
  • 2018(Publication Date)
  • Cambridge University Press

    (Publisher)

  It is thought to create a forward model that helps to predict the sensory consequences of a motor plan. • Via its connections through a series of loops through the thalamus and up into the cortex, the basal ganglia can mod- ulate the initiation and cessation of movements. They also play a role in motor planning and learning. • Primary motor cortex generates movement most likely by controlling the force or other parameters of muscle movement. • The supplementary motor complex is thought to be involved in specifying, preparing, and initiating a motor plan for an action, which is an abstract representation of an intended movement that is preprogrammed before the motor act is initiated. • Premotor regions are thought to specify the type of motor action (such as a grasp) that is necessary to perform a task. A portion of the premotor area, known as the frontal eye field, programs voluntary eye movements such as those involved in scanning visual space. • The anterior cingulate cortex plays an important role in the selection of motor responses, especially when they are novel or atypical. It also plays a role in the evaluation of the out- come of such movements, such as whether or not they lead to an error. • The right inferior frontal cortex has been suggested to play a specific role in the inhibition of motor responses. • The parietal lobe links movements with sensory informa- tion, including visual, proprioceptive, and kinesthetic information. It is thought to estimate what motor actions are required to meet a particular end state, and can aid in the on-line modulation of actions. It is also important for link- ing motoric actions to their conceptual significance, such as occurs when saluting or making the sign of the cross. • Complex action requires the coordinated effort of all these regions in an integrated manner.

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  The Single-Neuron Theory

  Closing in on the Neural Correlate of Consciousness

  • Steven Sevush(Author)
  • 2016(Publication Date)
  • Palgrave Macmillan

    (Publisher)

  In the 1990s functional MRI (fMRI) scans became available. These scans produced high-resolution cross-sectional images of function rather than of structure. A dynamic experimental paradigm became possible, one in which activity patterns could be imaged at high resolution while subjects were engaged in specific cognitive tasks. A wave of fMRI studies ensued that provided further evidence for the focality of cortical function.

  The Modern View: The Modular Cortex

  In the wake of these and other experimental findings, the case for localization of function in the cerebral cortex has now become overwhelming. Many functionally localized areas have been identified and extensively studied, including a number of language areas, more than twenty visual areas, and dozens of other specialized areas. Lashley’s contention that the cerebral cortex operates in an entirely homogeneous and diffuse manner may be respectfully laid to rest.

  The modern view is not, however, a mere reinstatement of Gall’s phrenology. With phrenology, the link between cognitive functions and focal cortical regions was one-to-one, each function being mediated by a single cortical region and each cortical region mediating only a single cognitive function. With the modern view, the correlations between cognitive functions and focal cortical regions are rarely one-to-one. Instead, each cognitive function is typically mediated by the combined activity of multiple focal regions, and each focal region is typically associated with multiple cognitive functions. Additionally, there are some psychological constructs, like intelligence and personality, that are hardly localizable at all. The functional arrangement of the cortex is therefore a hybrid that combines both focal and distributed themes. Neuroscientists commonly refer to this arrangement as modular .6

  Brodmann’s Map

  The modular arrangement was featured in a number of cortical anatomical maps that were published early in the twentieth century. The most widely used of these maps was that published in 1909 by the German neuroanatomist Korbinian Brodmann (1868–1918). Brodmann distinguished cortical regions on the basis of variations in the types of cells inhabiting each region and on the way these cells were distributed throughout the depth of the cortical sheet. Brodmann’s original map identified about 50 anatomically distinct cortical regions. Over the years, suggestions for further subdividing Brodmann’s regions have been offered, with some maps distinguishing as many as 100 separate cortical fields.

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  Duus' Topical Diagnosis in Neurology

  Anatomy, Physiology, Signs, Symptoms

  • Mathias Baehr, Michael Frotscher(Authors)
  • 2012(Publication Date)
  • Thieme

    (Publisher)

  Current thinking has turned away from the parceling out of functions to individual anatomical structures (as derived from the important studies of Brodmann, · 9 Cerebrum 239 9 Penfield, and many others) and toward the concept of functional neural networks . It is now clear that cortical functions, particularly higher ones like lan-guage, cognition, and the control of specific pat-terns of behavior, cannot always be assigned to a single cortical location. Rather, individual com-ponents of these complex functions are subserved by separate parts of the neocortex, which must then interact with each other in manifold ways to pro-duce the corresponding functional competence. In the past, the study of functional localization in the cerebral cortex relied on examination of the sick or injured brain (the “lesional approach”), and on nonphysiological experiments involving brain stimulation. In contrast, researchers now try to un-derstand the physiological basis and complexity of cortical functions by means of images of the entire normal brain, obtained while these functions are being carried out. The major techniques of functional neuroimag-ing that are used in this type of research are magnetoencephalography (MEG), positron emis-sion tomography (PET), and functional magnetic resonance imaging (fMRI). Magnetoencephalography involves measurement of the magnetic fields generated in the cerebral cortex, rather than changes in electrical potential, which are measured in electroencephalography. Brain tissue and the bony skull severely attenuate electric, but not magnetic fields, and MEG is, there-fore, much better than EEG for functional imaging. The magnetic fields that it detects are strong enough that a three-dimensional image of field sources can be computed from them, including sources deep in the brain. Functional imaging of the brain with MEG can be performed with high temporal resolution but relatively low spatial reso-lution (as compared to fMRI).

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  Topical Diagnosis in Neurology

  Anatomy, Physiology, Signs, Symptoms

  • Mathias Bähr, Michael Frotscher(Authors)
  • 2019(Publication Date)
  • Thieme

    (Publisher)

  9 Functional Localization in the Cerebral Cortex 245 · lobe processes somatosensory information (areas 1, 2, 3, and 5), its posterior portion integrates somatosensory with visual information to enable the performance of complex movements. Frontal Lobe The frontal lobe can be divided into three major components: the primary motor cortex (area 4), which has already been described, the premo-tor cortex ( area 6 , see below), and the prefrontal region , a large expanse of cortex consisting of mul-timodal association areas ( ▶ Fig. 9.18). The primary motor cortex and the premotor cortex form a functional system for the planning and control of movement. The prefrontal cortex is primarily concerned with cognitive tasks and the control of behavior. Premotor cortex. The premotor cortex ( area 6 ) is a higher-order center for the planning and selec-tion of motor programs , which are then executed by the primary motor cortex. Just as the unimodal association areas adjacent to the primary somato-sensory, visual, and auditory cortices are thought to store sensory impressions, so too the premo-tor cortex is thought to store learned motor pro-cesses, acting in cooperation with the cerebellum and basal ganglia. The stored “motor engrams” can be called up again for use as needed. Even tasks performed with a single hand activate the premotor cortex of both hemispheres. Another important function of the premotor cortex is the planning and initiation of eye movements by the frontal eye fields ( area 8 ; ▶ Fig. 9.17, ▶ Fig. 9.18, and ▶ Fig. 9.21). Unilateral stimulation of area 8 induces conjugate movement of both eyes to the opposite side. Lesions of area 8 that diminish its activity pro-duce conjugate gaze deviation to the side of the lesion through the preponderant activity of the contralateral area 8 (e.g., in stroke—“the patient looks toward the lesion”; cf. ▶ Fig. 4.24).

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