Dinner Analysis, Internal Representations - Lecture Slides | PSY 332, Papers of Cognitive Psychology

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week4.1: neuropsychology: parietal lobes

9.16.2008 / PSY

dinner example

imagine dinner with friends, you’re confronted with: a set of cutlery some dishes a basket of bread glass of H 20 a napkin and your friends amazingly w/out effort you select various utensils & foods & chat w/ your friends

internal representations

must be an internal representation of the location of different objects around us i.e., map in the brain where things are map must be common to all senses consider how easily we switch between visual to tactile information parietal lobe plays a central role in creation of brain maps

parietal cortex → f(x)

processes & integrates somatosensory & visual information esp. with regard to control of movement human parietal lobes evolved to much larger size than other primates

what is the map?

introspectively, real space must be mapped topographically b/c that’s how it appears to us wrong: there is no single map there is a series of representation of space e.g., consider allocentric space → space made up of the relations of objects, independent of observer perspective egocentric space → space relative to a persons perspective

aspects of parietal f(x)

visuomotor control center reaching certain eye-movements needed to grasp/manipulate objects grasping/manipulating objects arithmetic language

language

language has many of the same demands as arithmetic e.g., “tap” & “pat” have same letters, different spatial orientation e.g., “my son’s wife” & “my wife’s son” have identical words, different meanings language is quasi-spatial parietal patients my understand individual elements, not the whole when syntax is important

lesion symptoms: somatosensory thresholds

damage to postcentral gyrus associated with marked changes in somatosensory thresholds Josephine Semmes: WWII veterans w/ missile wounds to the brain Suzanne Corkin: cortical surgery for epilepsy high sensory thresholds, impaired position sense, deficits in stereognosis (tactile perception) e.g., pressure sensitivity, two-point threshold afferent paresis → movements of fingers are clumsy due to faulty feedback

lesion symptoms: somatoperceptual disorders 2

simultaneous extinction → characterized by response to stimuli on the neglected side as if there were simultaneous stimulation on the contralateral side normally people confronted w/ many stimuli simultaneously normally people can distinguish & perceive individual sensory perceptions test → double simultaneous stimulation: both stimuli reported if applied singly, but only 1 reported if both stimuli applied together

somatoperceptual disorders example

somatosensory agnosias 1

2 major types: (^1) asterognosis → inability to recognize the nature of an object via touch (^2) asomatognosia → loss of knowledge or sense of one’s own boy & bodily condition

somatosensory agnosias: anosognosia

anosognosia → unawareness or denial of illness relatively common (20-30%) following brain injury, such as hemiplegia/hemiparesis after stroke not directly related to sensory loss caused by damage to higher level neurocognitive processes involved in integrating sensory info w/ processes that support spatial or bodily representations schizophrenia vs. limb movement disorders denial vs. unawareness?

autopagnosias: finger agnosia

finger agnosia → unable to point to various fingers of either hand or show them to an examiner relation exists between finger agnosia & discalculia when kids learn arithmetic they usually use their fingers to count children with spina bifida (neural tube deficit wherein fetus’s spine doesn’t close properly during month 1 of pregnancy) have finger agnosia & have trouble w/ arithmetic

Balint’s Syndrome

1 35 ◦-40◦^ directed gaze at stimulus (^2) simultaganosia → field of attention limited to 1 object at a time (makes reading a nightmare) (^3) optic ataxia → severe deficit reaching under visual guidance (i.e., make visually guided hand movements)

patient description (Damasio & Benton, 1979, p. 171)