Lec 54 Cerebral Cortex Flashcards
What is the allocortex?
division of cerebral cortex containing:
- archicortex [hippocampus]
- paleocortex [parahippocampal]
What is isocortex?
division of cerebral cortex = the neocortex
What are the 5 major neocortical afferents?
- thalamus
- neocortex
- amygdala
- parahippocampal areas
- diffuse NT projects [extrathalamic]
What is the function of neocortical afferents from the thalamus? where do efferents back to thalamus come from?
afferents from thalamus: initial representation of topographic maps, nuclei linked to regions
efferents to thalamus: reciprocal projects from layer 6
What is the function of neocortical afferents from the neocortex? what about efferent back to neocortex?
afferents from neocortex: cortico-cortical circuits
efferents to neocortex: reciprocal cortico-cortical circuits
What is the function of neocortical afferents from the amygdala? where do efferents back to amygdala come from?
afferents from amygdala: emotional tone to neocortex function
efferents to amygdala: from primary prefrontal and cortex
What is the function of neocortical afferents from the parahippocampal areas? where do efferents back to parahippocampal areas come from?
afferents from parahippocampal areas: role in memory
efferents to parahippocampal areas: from association cortex
What is the function of neocortical afferents from the extrathalamic diffuse projectiosn?
MOA/ACh neurons, regulate mood, attention
Where do amygdala afferents project to in neocortex?
project to prefrontal cortex [PFC], temporal lobe
What are the major neocortical efferents?
- to thalamus: reciprocal from layer 6
- to neocortex: reciprocal
- to amygdala: from primarily prefrontal + temporal
- to parahippocampal from association cortex
- to brainstem: pons, motor nuclei, tectum
- spinal cord
Which layer of neocortex receives input from thalamus? which projects back?
layer 4 = receives input
layer 6 = projects back
What is unique about laminar structure of V1?
- highly elaborated layer IV for thalamic input [3 sublayers]
- small V that projects to brainstem
What is unique about laminar structure of V2?
- extra layer of pyramidal cells that V1 doesn’t have = characteristic of an association cortex
What is unique about laminar structure of M1?
- elaborated layer V with betz cells = motor output to distal digits
- no layer IV
What are the classic output layers? classic input layers?
classic output = 5, 6
classic input = 4
What is structure of 3 layer 4 sublayers in V1?
4a and 4c = stellate, receive thalamic input
4b = pyramidal cells
What is function of pyramidal neuonrs?
- principle output neurons
- excitatory [glutamate]
- regulated by interneurons
- spiny
What output pyramidal neurons in each of layers 2, 3, 5, and 6?
layer 2/3 = cortical-cortical
layer 5 = to striatum, brainstem, spinal cord
layer 6 = to thalamus
What are 3 types of inhibitory interneurons in cerebral cortex?
double bouquet = modulating, synapse distally
basket cells = wrap cell body, implicated in epilepsy
chandelier = most powerful, wrap axon hillock
What are spiny stellate interneurons?
excitatory interneurons
- only in layer IV of S1 V1
- receive input from thalamus
Where are the pyramidal neurons associated with ALS?
loss of brainstem and spinal cord pyramidal neurons in layer 5
Where are the pyramidal neurons associated with Alzheimer’s?
loss of cortical cortical projections in layers 2, 3, 5
What are the 4 types of extrathalamic subcortical afferents to the neocortex?
- NA from locus coerulues in pons
- 5HT from dorsal raphe in midbrain
- DA from VTA in midbrain
- ACh from nucleus basalis
*go to all layers of neocortex
What types of circuits are glutamate neurons linked to?
corticocoritcospinal and cortex-thalamic circuits
What circuits are GABA neurons linked to?
local interneurons
What circuits are MOA/ACh linked to?
global, diffuse modulation throughout cortex
