PSYC31: Ch8

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Department
Psychology
Course
PSYC31H3
Professor
Konstantine Zakzanis
Semester
Winter

Description
PSYC31- Chapter 8 Diffuse and Focal Effects - concepts more clear cut than manifestations Diffuse Effects Focal Effects - behavioral expression - cause most: trauma, space displacing lesions (i.e. tumors, memory, attention, concentration disabilities blood vessel malformations), localized infections, impaired higher level and complex reasoning- cerebrovascular accidents conceptual concretism, inflexibility - systemic conditions too severe thiamine deficiency - occasionally accompany acute exacerbation of systemic response slowing - emotional flattening or lability (constantly undergoing disorder i.e. diabetes confusing the diagnostic picture change) until underlying disorder brought under control and organic - these symptoms most severe immediately after injury or symptoms subside early stages of sudden onset disease OR first appear as - distinguished by lateralizing signs since most discrete lesions involve only one hemisphere subtle transient problems that increase in duration and severity as condition worsens - when both hemispheres, damage apt to be assymetrical - symptoms almost always accompany focal lesions of predominance of lateralized symptom pattern sudden onset - generally when one function or several are significantly - i.e. cloudy consciousness, confusion, slowed impaired while others remain intact examiner can responsiveness may obscure focal residual effects conclude focal injury evidence focal injury wont known until later - ultimately, diffuse effects resulting from increased intracranial pressure and circulatory changes may obliterate specific defects due to local tissue damage - Site and Size of Focal Lesions - site of lesion determine many characteristics of attendant behavioral alterations - expression of changes severity, intransigency, burdensomeness depends on other variables that just the location of lesion makes prediction of symptoms virtually impossible - localizing lesion and localizing function not identical operations - certain areas of brain may be critical for specific cognitive functions but brain regions not isolated work interconnected, distributed neural networks - evidence by neuroimaging - lesions in one area may disrupt network and produce impairment similar to lesions in another area within network - each area contirbtue to some aspect of cognitive processing www.notesolution.com- clinical practice, few patients iwht primary focal lesions have damage confined to the identified area - stroke patients lesion site more likely to predict nature of NP deficits than its size volume - i.e. small subcrotical lesions can have major effects - complexity of site vs. size site more important determing language behavior while lesions size may be a factor in severity of articulatory impairment - while others believe both size and site contribute to severity of dysfunction - CT measures of stroke: severity estimated best by taking into account both size and hemisphere of lesion - TBIs rarely clean (except for missile, puncture wounds) size of lesion impt determinant of residual functional capacity - tumors widespread throughout brains boundaries erratic in destruction of nervous tissue - location of lesion only partial description of primary site of damage - patterns behavior and NP test results may not meet cookbook expectations of lesion Depth of Lesion - subcortical damage added effects of disrupted pathways or damaged lower integration centers - depth and extent of cortical lesion involving subcortical damage alter behavioral correlates of similar cortical lesions - depth of lesion = related to severity of impairment of verbal skills - i.e. anosognosia impaired awareness of ones own disabilities or disabled body parts, associated with right parietal lobe damage illustrate differences in behavioral correlates of similarily situated cortical lesiosn with different amounts subcortical involvement - lesions of right optic region of thalamus = anosognosia with neglect of paralyzed side - lesions penetrating only transmission fibers from thalamus parietal cortex = anosognosia with amnesia or lack of recognition of affected limbs or side - lesions to parietal cortex = anosognosia with positive psych symptoms confabulation, delusions Distance effects Diaschisis: chronic depression of activity that place in areas of brain outside immediate site of damage usually associated with acute focal brain lesiosn - originally thought of shock to nervous system due to disruptions in neural network www.notesolution.com
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