MODULE 12- Cognitive Functions and the Organization of the Cerebral Cortex Flashcards
cognitive functions are carried out by
association cortices
how many layers of neocortex
6 layers
cytoarchitectonic areas of neocortex
subregions based on histological differences
-the archiecture of neurons and their processes and connections
-much variability in cytoarchiectonic areas among species and individuals
-BRODMANN’S AREA
the human brain can be divided into ____ cytoarchitectonic areas based on histology
50
3 layers of cerebral cortex
-neuocortex
-paleocortex
-archiocortex
how many layers of paleocortex
3
how many layers of archiocortex
4
layer 1 of neocortex
mostly neuropil
layers 2 and 3 of neocortex
smaller pyramidal neurons with corticocortical connections
layer 4 of neocortex
stellate neurons with locally ramifying axons
layers 5 and 6 of neocortex
pyramidal neurons with exiting axons
similarites among the different cytoarchitectonic areas
-each cortical layer has primary source of input and a primary output target
-each area has vertical columnar or radial connections
-interneurons give rise to extensive axons that extend horizontally within the cortex and link functionally similar groups of cells
thalamic input to which layer
4
input from brainstem does what
modulates each layer
3 unique features of association cortices
- Inputs via the thalamus (e.g., pulvinar, medial dorsal nucleus) reflects sensory and motor info that has already been processed in the primary sensory and motor areas of cerebral cortex.
- Enriched corticocortical connections and interhemispheric connections.
- Enriched subcortical connections (i.e., dopaminergic nuclei in midbrain, noradrenergic and serotonergic nuclei in the reticular formation, and cholingergic nuclei in the brainstem and basal forebrain).
connectivity patterns wtihin cerebral cortex
implications for behavioral and psychiatric disorders
(ex: addiction, depression, attention deficit disorder, psychoses)
synesthesia
mixing of senses (ex: colored hearing, colored graphemes, or colored taste)
-in one of the most common forms of synesthesia, black and white letters or digits are perceived in assorted colors
-colored touch and smell have also been reported
potential cause of synesthesia
“miswiring” as new synaptic connections are established
parietal association cortex
attention and awareness
contralateral neglect syndrome
inability to attend to objects or even one’s own body, in a certain space, despite visual acuity, somatic sensation, and motor ability
-OPPOSITE the parietal lesion
caveat of contralateral neglect syndrome
-associated with damage to the RIGHT parietal cortex
-right parietal cortex mediates attention to both the right and left halves of the body and extrapersonal space, whereas the LEFT hemisphere mediates attention primarily to the right, perhaps because of the left hemisphere’s devotion to language functions
lest hemisptial neglect is caused by
damage to right inferior parietal lobe
when are neurons in the parietal cortex activated
when the animal attends to a target, but not when the same target is ignored
Balint’s syndrome
bilateral damage to dorsal posterior parietal and lateral occipital cortex
Balint’s syndrome causes waht 3 things
-simultanagnosia
-optic ataxia
-ocular apraxia
simultanagnosia
inability to perceive more than 1 visual object at a time
optic ataxia
difficulty in visually guided reaching
ocular apraxia
difficulty in voluntary scanning of visual scenes
simultagnosia test
patients take a clearly piecemeal approach to interpreting the scene by reporting isolated items from the image
-for instance, a patient may report seeing a “boy,” “stool,” and a “woman”
-however, when asked to interpret the overall meaning of the picture, the patient fails to comprehend the global whole
agnosias arise from
temporal lobe damage
how do agnosias present
difficulty in identifying, naming, and recognizing objects
right temporal lesions lead to agnosia for what
faces and objects
left temporal lesions lead to what agnosia
difficulties with language-related material
prospagnosia
arises from damage to the RIGHT inferotemporal cortex (ITC)
how does prosopagnosia present
inability or difficulty in recognizing and identifying faces or people
visual agnosia
inability to recognize visual objects
-can copy visual stimuli
-cannot interpret, understand, or assign meaning to objects
-a patient with visual agnosia can see perfectly well but is no longer able to recognize or make sense of what he sees
visual agnosia is caused by
damage to inferior left temporal cortex (IT)
what mediates face recognition
inferior temporal cortex, particularly RIGHT fusiform gyrus
frontal association cortex
planning and decision making
damage to prefrontal cortex results in
behavioral and social problems, such as acting inappropriately to certain social circumstances
damage to prefrontal cortex was seen in the famous case of
Phineas Gage
-metal rod went through skull
-dramatic effects on personality
short term memory functions are situation ____ in the frontal lobe
dorsolateral
planning and social restraint function are located ____ in the frontal lobe
ventromedial
wisconsin card sorting task
to respond correctly, the subject must retain information about the previous trial, and then use it to guide behavior on future trials
-sort by color, shape, number
activation in the ____ correlates with subjective preferences for soft drinks
ventromedial prefrontal cortex
prefrontal cortex contributes to
planning adaptive behavior
delayed response task
used to assess frontal lobe damage and determine whether short term memory is intact
delayed task response used on monkeys
- food is placed in a randomly selected well visible to monkey
- screen is lowered and the food is covered for a standard time
- screen is raised and monkey uncovers the well containing the food
-the animal has to remember where the food is placed during the delay so that it can be used to get reward
-some neurons in the prefrontal cortex are activated maximally during the delay period
