Cerebral Cortex Flashcards
Terminology (neocortex, archicortex)
neocortex - 90%, all areas have 6 layers some time during development
archicortex - “older” 3 layers, hippocampus
Pyramidal Cells
principle protection cell - project to other cortical rergions or to subcortical targets
spines on dendrites - involved in learning, change in shape changes sensitivity to stimuli
dendritic tree develops after birth
Cortical Layers
6 layers, 5th contains pyramidal cells that project out of cortex
Cortical Connections - Afferents
other areas of cortex
subcortical areas - thal, some direct projections from BS
Cortical Connections - Efferents
subcortical - SC, BS, BG thal (via internal capsule); 5th layer main source of projections
cortical - commisural (to other hemi, most use CC, part of temp lobe uses ant commisure), association (same hemi, short fasciculi)
Vertical Organization of Cortex
in some areas, all cells in column oriented perpendicular to surface of cortex respond best to certain type of stimulus
SS (particular type of sensory stimulus), visual (bar oriented at particular angle; show preference for one eye or the other)
not seen everywhere cause not sure which stimulus is “best” (i.e. association cortex)
Brodmann’s Area
divided each hemi into 52 regions based on histological difference
some coincide with distinct functional areas
Cortical Areas in General
primary sensory and motor areas, association areas, limbic areas
Primary Sensory Areas
cells response to specific modality
Primary Motor Areas
cells produce very discrete movements
Association Areas
compromise most of human cortex
Association Areas Cells
unimodal (modality specific) - cells respond to complex input regarding single type of stimulus
heteromodal (higher order) - cells respond to various types of stimuli (touch, vision, limbic) related to functions such as recognition, visual spatial skills
SS Cortex
3 vertical strips on postcentral gyrus - differ histologically and by receptors they represent, homunuclus
Cerebral Dominance
language usually localized in L hemi (aka dominant hemi)
dominant (L) hemi also ability to do math, problem solve in sequential/logical fashion
non-dominant (R) - musical ability, recognition of faces, tasks requiring comprehension of spatial relationships
EEG
measures only cortical function
extracellular post-synaptic potentials
summation of synchronous activity of groups of neurons
records different wave forms that reflect different oscillating currents in cortex
used to dx seizure, dementia, disorders of consciousness, sleep disorders
Evoked Potentials - Visual
sitmulate with visual stimulus on screen
record over visual cortex
can test blindness in infants, optic neuritis in MS
Evoked Potentials - Auditory
stimulate with sound in ears
cochlear nerve to lat lemniscus to med gen to cortex
can be test in brain injury and for hearing loss
Evoked Potentials - SS
stimulate at post tib, median, ulnar nerves
record at scalp, look at amp and latency of peaks
can test for compressions along way (Arnold Chiari) and for slowing in transmission (MS)
