cerebral cortex higher functions

occular dominance columns

process visual information from either the right of left eye alternating from one eye to the other — essential for binocular vision and depth perception

monocular deprivation

during critical developmental periods, the non-deprived eye will take over cortical areas that would have been devoted to the deprived eye

pediatric strabismus

misalignment of the eyes causing double vision, leading the brain to suppress input from one eye and lead to functional monocular vision

blindsight

subconscious spatial awareness of visual stimuli from extrageniculate pathways

inputs to visual association cortex

V1 via LGN, superior colliculus and pulvinar nucleus via extrageniculate pathway

visual association cortex function

mediate complex aspects of vision — recognize and localize visual stimuli, tracking eye movements

Dorsal stream

output of VAC to superior parietal lobe for localization of objects in space and reading

ventral stream

output of VAC to middle and inferior temporal gyri for conscious awareness and recognition of visual stimuli

cerebral achromatopsia

due to dysfunction of VAC — patients cannot distinguish, point to, or match colors presented visually, but can name the appropriate color for an object described verbally

visual agnosia (aperceptive agnosia)

due to dysfunction in VAC — inability to name or recognize the significance of a visual stimulus, but conscious awareness of the object is preserved

inferior parietal lobule

outputs of auditory association cortex important for language and reading

hippocampus and amygdala

outputs of auditory association cortex important for auditory experiences and emotional aspects of auditory experiences

functions of PAC

processing of auditory info, ID sounds, store auditory memories

dominant hemisphere AAC dysfunction

word deafness — fluent aphasia

non-dominant hemisphere AAC dysfunction

amusia — disturbances in the appreciation of music

primary functions of visual association areas in temporal lobe

store visual memories, whole object recognition, recognition of complex visual patterns

ventral stream damage

damage to the “what” pathway — inability to recognize objects by sight

associative visual agnosia

visual acuity intact, but object identification is impaired (most commonly seen after dominant hemisphere damage)

prosopagnosia

inability to recognize faces, assocciated with bilateral damage to inferior temporal or fusiform gyri

function of somatosensory association cortex

integration of somatosensory information, stereognosis

tactile agnosia (asterognosis

inability to correlate texture, shape, size, weight, etc. of a somatosensory stimulus with previous experience

posterior parietal cortex

major site of reciprocal connections with association cortices, pulvinar and lateral nuclei of the thalamus, frontal cortical regions

PPC function

multi-modal sensory integration area crucial for direction attention toward specific stimuli in the environemnt

bottom-up processing

attention is captured by a sensory stimulus and the PPC recruits frontal cortex to produce appropriate response — automatic, exogenous

top-down attention

mental representation guides behavior as you search the environment for a stimulus — effortful, endogenous

PPC dominant hemisphere function

language function — reading, writing, mathematical ability

PPC non-dominant hemisphere function

spacial representations of stimuli, focusing attention on sensory input

Gerstmanns syndrome

PPC damage in the dominant hemisphere — finger agnosia, left-right confusion, acalculia (impaired ability to perform math), agraphia

spatial neglect

PPC damage in the non-dominant hemisphere — impaired understanding of spatial relationship, anosognosia (denial of disability), contralateral neglect

simultagnosia

damage to bilateral PPC leading to inability to perceive multiple objects — core feature in balint’s syndrome

insular lobe function

visceral sensation and autonomic regulation, integration of olfaction and taste, vestibular sensation, interoception

motor apraxia

an impaired ability to carry out purposeful, complex, voluntary movements inthe absence of paralysisapr

anterior (premotor) apraxia

will perform poorly on motor tasks, but perception will remain intact

posterior (paraietal) apraxia

will perform poorly on both motor and perceptual tests

alien hand sign

limb acting on its own volition, but the patient still perceives ownership of the limb

FEF dysfunction

deviation of the eyes toward the side of the lesion with impairment of voluntary conjugate gaze toward the opposite side

prefrontal cortex function

executive function, planning, attention, foresight, abstract thought, working memory

prefrontal cortex dysfunction

difficulty planning and executing complex behaviors, personality changes, socially inappropriate behavior, inability to understand consequences, loss of aversive aspect of pain

broca’s area

speech production, coordinate movements of the tongue, lips, and larynxbro

broca’s aphasia

expressive/nonfluent aphasia — paucity of speech, tremendous difficulty of speech production, language comprehension intact

wernicke’s area

language comprehension of spoken and written words

wernicke’s aphasia

receptive/fluent aphasia — normal rate, rhythm, intonation of speech, but language may be excessive and speech may include neologisms, failure to convey coherent message

conduction aphasia

damage to the arcuate fasciculus, which connects the language comprehension center in the temporal lobe with the language production center in the frontal lobe — fluency and comprehension is good, but reading aloud is impaired, writing and naming are impaired

hallmark sign of conduction aphasia

inability to repeat individual nonsense words or unrelated sequences of common words