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Chapter 2

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Department
Psychology
Course
PSYB51H3
Professor
Steve Joordens
Semester
Summer

Description
PSYB57 – Chapter 2: The Neural Basis for Cognition Capgrass Syndrome: An Initial Example  Rare; seems to be one of the accompaniments to Alzheimer’s disease and is sometimes observed in the elderly  The people with this are convinced that the people they know are not who they appear to be  They think that their family members have been replaced by imposters  This can lead to paranoid suspicions about why a loved one has been replaced and why no one is willing to acknowledge this replacement  Facial recognition involves two separate systems o Cognitive appraisal o Emotional appraisal  The emotional appraisal is disrupted in this syndrome leading to the intellectual identification without the familiarity response The Neural Basis for Capgras Syndrome  Current studies rely on MRI scans  Right temporal lobe is damaged in Capgras patients and this damage disrupts circuits involving the amygdala  Amygdala serves as an emotional evaluator helping an organism to detect stimuli associated with threat or danger and for detecting positive stimuli  Capgras patients also have damage in the prefrontal cortex  fMRI allow us to track moment-by-moment activity levels in different sites in a living brain  prefrontal cortex is active when person is engaged in tasks that require planning, or careful analysis and it is less active when dreaming  Capgras patients are less able to keep track of what is real and what is sensible; weird beliefs can emerge unchecked, including delusions What Do We Learn From Capgras Syndrome?  Damage to the amygdala is probably the reason Capgras patients experience no sense of familiarity when they look at faces they know well  The damage to prefrontal cortex helps us understand why Capgras patients offer crazy hypotheses about their skewed perception  Capgras syndrome can be used to illuminate broader issues about the nature of the brain and of the mind  It suggests that the amygdala plays a crucial role in supporting the feeling of familiarity and the biological evidence suggests that the amygdala also plays a central part in helping people remember the emotional events of their lives The Study of the Brain  Brain weighs about 3-4 pounds  Contains large number of glial cells  Phineas Gage damage to front-most part of his brain led to severe personality and emotional problems Hindbrain, Midbrain, Forebrain  Hindbrain has structures crucial for controlling key life functions and also plays an essential role in maintaining the body’s overall tone o It helps maintain the body’s posture and balance and helps control the brain’s level of alertness o Largest area of hindbrain is cerebellum and damage to this can cause problems in spatial reasoning, in discriminating sounds, and in integrating the input received from various sensory systems  Midbrain plays important role in coordinating movement and the circuits that relay auditory info from the ears to the areas in the forebrain where this info is processed and interpreted  The largest region is the forebrain o The cortex is the outer surface of the forebrain o Cortex constitutes 80% of the human brain o The convolutions are the brain’s most obvious visual feature o Longitudinal fissure = deepest groove which separates the left cerebral hemisphere from the right o Central fissure divides the frontal lobes on each side of the brain from the parietal lobes o The bottom edge of the frontal lobes is marked by the lateral fissure, and below it are the temporal lobes o At the very back is the occipital lobe Subcortical Structures  Underneath the cortex are the subcortical parts of the forebrain  Thalamus = relay station for all sensory info going to cortex  Hypothalamus = plays crucial role in controlling motivated behavior  Limbic system = include the amygdala and hippocampus; essential for learning and memory Lateralization  Cortical and subcortical structures appear in both sides of the brain in roughly the same structure  Commisures connect the 2 hemispheres and carry info back and forth from one hemisphere to the other o Largest commissure is the corpus callosum Data from Neuropsychology  Neuropsychology = study of the brain’s structures and how they relate to brain function  Symptoms developing from brain damage depend heavily on the site of the damage  A lesion in the hippocampus produces memory problems but not language disorders  Damage to left side of frontal lobe = disruption of language use  Different brain areas produce different functions Data from Neuroimaging  CT scans study brain structure while PET scans study brain activity  CT relies on X-ray and provides 3D image  PET uses a tracer substance and tells which tissues are using more glucose  CT scans tell size, shape and position of structures within brain and PET tells which regions are active at any point in time  MRI uses magnetic properties of atoms that make up brain tissue  fMRI measures the oxygen content in blood flowing through each region of the brain (precise pictures)  CT and MRI scans are stable while PET and fMRI change with activity Data from Electrical Recording  Because millions of neurons are active at the same time, the current generated by them is enough to be detected by electrodes on the scalp (EEG)  EEGs are used to study broad rhythms in the brain’s activities  To measure the changes in EEG in a brief period just before, during and after an event are changes referred to as event-related potentials (ERPs) The Power of Combining Techniques  Researcher combine the scans and techniques from different sources so as to use the strength of one technique to make up for the shortcomings of the other  Neuroimaging data can tell us that a brain area’s activity is correlated with a particular function, but we need to ask whether the brain site plays a role in causing that function  Transcranial magnetic stimulation (TMS) creates a series of strong magnetic pulses at a specific location on the scalp, causing temporary disruption in the brain region directly underneath this scalp area  TMS procedure can provide crucial info about functional role of that brain area Localization of Function  Aims toward figuring out what’s happening where within the brain The Cerebral Cortex  3 categories o Motor areas – contain brain tissue crucial or organizing and controlling body movements o Sensory areas – contain tissue essential for organizing and analyzing info we receive form senses o Association areas Motor Areas  Primary motor projection area – departure point for signals leaving the cortex and controlling muscle movement  Primary sensory projection areas – arrival points for info coming from eyes, ears, and other sense organs Sensory Areas  Each of the sensory areas provides a map of the sensory environment  In each of the sensory maps, the assignment of cortical space is governed by function, not by anatomical proportions  Evidence for contralateral connections comes from the sensory areas Association Areas  Perform tasks of associating simple ideas and sensations in order to form more complex thoughts and behaviors  This terminology is becoming disused  Apraxia = disruptions in the initiation or organization of voluntary action  Agnosia = disruptions in the ability to identify familiar objects; usually affect one modality only  Neglect syndrome= individual ignores half of their visual world  Aphasia= disruption to language capacities  Damage to prefrontal area = problems of planning and implem
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