Raj - thalamus, cerebral cortex Flashcards
forebrain (prosencephalon)
contain diencephalon and cerebral hemisphere
thalamus
gateway to cerebral cortex
-nerve fibers run within internal medullary lamina
nuclei of thalamus - lateral nuclear group specifics
- ventral posteromedial, posterolateral –> somatosensory cortex
- ventral lateral –> primary motor
- ventral anterior –> premotor and supplementary motor cortex
thalamic lesions
- vascular accidents = posterior cerebral and posterior communicating arteries
- strokes, tumors –> loss of sensation on contralateral side; mimic cortical defects
lateral vs. medial geniculate nucleus
lateral - visual
medial - auditory
nuclei of thalamus - lateral nuclear group nonspecifics
- lateral dorsal –> cingulate gyrus; limbic system
- lateral posterior –> sensory association cortex in parietal lobe
- pulvinar (largest) –> parieto-occipital-temporal association cortex
anterior nuclear group
anteroventral, -medial, -dorsal
-project to cingulate cortex –> limbic system
medial nuclear group
mediodorsal nucleus –> efferents to prefrontal cortex (mood and emotions)
reticular nucleus
only nuclei sending efferent to thalamus and not cortical areas
-inhibitory (GABA) efferents
neocortex
6 layers
- layer 4 –> termination of afferent fibers of thalamic nuclei
- layer 5 –> origin of extracortical targets; in primary motor cortex; contain Betz cells
central sulcus
- behind –> post central gyrus (primary somatosensory cortex)
- in front –> pre central gyrus (primary motor cortex)
- separates frontal from parietal lobe
brodmanns areas
- somatosensory –> area 1, 2, 3
- primary motor –> area 4
- premotor –> area 6
- frontal eye field –> area 8
- brocas area –> 44, 45
- primary auditory –> area 41, 42
- primary visual –> area 17
motor cortexes
- premotor cortex - less focused
- supplementary motor - role in posture
- both help primary motor cortex
frontal eye field
control conjugate eye movements
- area 8
- unilateral damage –> conjugate deviation of eyes towards side of lesion
brocas area
motor speech area in dominant hemisphere
-language function - connections to temporal, parietal, occipital
left frontal lobe lesions
- partial seizures - contralateral jerking movements (Jacksonian seizures)
- sensory/motor deficit - weak face and UMN on opposite side (contralateral hemiplegia)
- psychological deficit - trouble speaking, good comprehension (broca’s aphasia)
bilateral cortical disorders
- Alzheimer’s disease = degenerative
- atrophy of temporal, parietal, and limbic system
- aphasia (lose language) and amnesia (lose memory) - General paralysis of insane = neurosyphilitic infection
- destroy both frontal lobes
- alter personality, judgement, planning, behavior
association cortex of parietal lobe
- superior parietal lobule - interpretation of sensory info. and awareness of contralateral half of body
- inferior parietal lobule - interface b/w somatosensory, visual, and auditory (language in dominant hemisphere)
- damage –> visual and auditory problems
parietal lobe lesions
- left parietal lobe lesion
- partial seizures
- sensory/motor deficit - lose inferior visual field
- psychological deficit - cannot name (anomia), read (Alexia), write (agraphia), or calculate (acalculia) - right parietal lobe lesion
- same as above
- psychological deficit - inability to copy and construct designs bc of spatial disorientation (constructional apraxia)
auditory association cortex
known as wernickes area in dominant hemisphere
-understanding/comprehending language
left temporal lobe lesions
- partial seizures - unresponsiveness (absences), behavior (automatism), olfactory visual and auditory hallucinations, memory and mood disturbance (de ja vu)
- contralateral superior visual field affected
- fluid speech, word errors (paraphasia), incomprehensible (wernicke’s aphasia)
occipital lobe lesions
- visual hallucinations
- contralateral visual field loss (contralateral homonymous hemianopia)
- bilateral lesion –> cortical blindness (Anton’s syndrome)
- prevent recognition (apperceptive visual agnosia)
