cerebral hemisphere functional topography

primary sensory cortex

discriminate qualities of sensory info, where info goes first, most basic processing

sensory association cortex

complex analysis of sensation from thalamus and primary sensory areas

primary motor cortex

executes motor plans

motor planning areas

organizes movements, plan/organize movement strategies

association cortex

controls behavior, interprets sensation, processes emotions and memory

unimodal association cortex

only relevant info to 1 system

heteromodal association cortex

collect info from multiple systems and integrates

primary somatosensory cortex

area 3, 1, 2
receives tactile, proprioceptive, pain and temp
discriminates shape, texture, size of objects
organization: sensory homunculus

primary somatosensory lesion

loss of tactile localization and conscious proprioception, impaired ability to discriminate intensity or assess quality
crude awareness thermal stimuli occurs in thalamus and nociception also processed in sensory association so may not be as affected

primary auditory cortex

area 41, lat fissure on adjacent sup temporal gyrus
receives info from cochlea of both ears from med geniculate
low frequency: anterolateral, high frequency: posteromedial
conscious discrimination of loudness and pitch of sounds

primary auditory lesion

loss of localization of sounds

primary visual cortex

area 17, in calcarine sulcus and adjacent gyri, sees contra visual field
receives info from lat geniculate body
upper field: lower wall, lower field: upper wall
distinguishes intensity of light, shape, size, and location of objects

primary visual lesion

homonymous hemianopia or other field deficits depending on size of lesion in contra visual field

primary vestibular cortex

more unconscious, post to primary somatosensory
discriminates among head positions and head movements, contributes to perception of vertical

primary vestibular lesion

change in awareness of head position and movement and perception of vertical, lateropulsion

secondary sensory areas

usually adjacent to associated primary area, complex processing that allows identification

secondary somatosensory

superior aspect of parietal lobe posterior to SI
stereognosis and memory of tactile and spatial environment

secondary somatosensory lesion

astereognosis, contra cortical neglect

secondary visual

surrounds visual cortex
analysis of motion, color
recognition of visual objects, understanding of visual spatial relationships, control visual fixation, visual memories of past, hallucinations, recognition of faces

secondary visual lesion

visual agnosia (ex prosopoagnosia - usually bilat damage to inf visual association areas) or optic ataxia

secondary auditory

includes Wernicke’s area
classification of sounds

secondary auditory lesion

auditory agnosia
on L causes Wernicke’s aphasia, on R unable to interpret noises

primary motor cortex

area 4, precentral gyrus
selective motor control/motor execution, source of many UMN, control contra movement, fine movement
bilat projections to upper face and back muscles
homunculus has largest area for hands and face and smaller representation for trunk/proximal limbs

primary motor lesion

contra paresis, loss of selective motor control (synergies), loss of fractionation, spastic dysarthria (speech disorder) - speech is harsh and awkward

premotor cortex

area 6
more axial, control of trunk and girdle muscles, APAs

premotor lesions

apraxia, agraphia

supplementary motor area

area 6
initiation of movement, orientation planning, control of bimanual and sequential movements

Broca’s area

left
motor programming of speech, planning mouth movement and grammatical aspects of speech

lesion to Broca’s

Broca’s aphasia

inf frontal gyrus in R hemisphere

same area as Broca’s but on right
planning nonverbal communication, gestures, adjusts tone of voice

inf frontal gyrus R hemisphere lesion

difficulty producing nonverbal communication

supplementary motor lesion

apraxia, motor perseveration, agraphia

association cortex

helps you see options/opportunities
controls behavior, interprets sensation, processes emotions and memory, create/modify goals, big picture cognitive plans

prefrontal association cortex

ant part of frontal lobe
connects with sensory association cortex in parietal, occipital, and temporal lobes, and limbic system
self-awareness and executive functions (deciding on goal, planning how to accomplish, executing plan, monitoring execution)

prefrontal impairments

loss executive functions and divergent thinking, apathy, lack of initiative, lack goal-directed behavior, difficulty choosing goals, planning/executing/monitoring plans, difficulty conceiving of possibilities, little effect on intelligence

parietotemporal association cortex

junction parietal, occipital, temporal lobes
intelligence, problem solving, comprehension of communication, spatial relationships

parietotemporal impairments

problems with communication, understanding, and directing attention
on L: Wernicke’s aphasia
on R: deficits directing attention, comprehension space, understanding nonverbal commands

limbic areas

regulates mood, affect, and processing memory, behaviors, personality

limbic impairments

personality and emotional changes
orbitofrontal cortex: inappropriate or risky behavior, poor judgement but intact intellect, say/do things socially unacceptable

thalamic injury

relay nuclei: loss of sensation and proprioception
thalamic pain: involve severe contra pain with/without provoking stimulus

internal capsule impairments

from occlusion or hemorrhage of lenticulostriate, small lesions can have severe consequences

basal ganglia disorders

lenticular dysfunction: hypokinetic or hyperkinetic
caudate: rarely causes motor disorders but does cause behavioral disturbances

acute cerebellar infarction

dizziness/vertigo, lack of balance, nausea, vomiting, dysarthria, HA, ataxia, hypotonia

ACA insufficiency

personality changes, confusion, difficulty bimanual tasks, urinary incontinence (especially bilat), apraxia, contra hemiplegia and hemisensory (mainly lower)
deep branches: motor dysfunction d/t putamen and frontopontine axons

MCA insufficiency

stereotyped posture: increased tone in hemiplegic limb, add of shoulder/flex elbow/ext throughout LE
loss of contra visual field, contra hemiplegia and hemisensory (UE and face more)
language impairment, difficulty spatial relationships, neglect, nonverbal

lenticulostriate and ant choroidal insufficiency

contra hemiplegia and hemisensory loss with homonymous hemianopia

PCA insufficiency

midbrain: contra hemiparesis and eye movement paresis
calcarine branches: contra visual field blindness
thalamus: thalamic pain syndrome, contra loss sensation, flaccid hemiparesis
hippocampus: interfere with declarative memory

watershed area insufficiency

upper limb paresis and paresthesias

vertebral and basilar artery insufficiencies

complete occlusion causes death
partial occlusion: tetraplegia, loss of sensation, coma, CN signs