Cerebral Cortex Flashcards
Allocortex
Hippocampus and parahippocampal cortex
Isocortex
The neocortex
Where does the neocortex receive afferents from?
Thalamus
Neocortex
Extrathalamic subcortical (monoamines and cholinergic projections from brainstem)
Amygdala (confers emotional tone to neocortical areas)
Parahippocampal areas, role in memory
Major neocortical efferents
Thalamus (reciprocal projections from layer 6)
Neocortex
Amygdala
Parahippocampal gyrus
Basal Ganglia (NOT reciprocal)
Projections to downstream areas of motor cortex
How many layers of neocortex?
6
Explain regional specialization of the neocortical layers
Depending on the area of the brain, the layers are thicker/thinner. For example V1 has big layer IV (where thalamus inputs). Motor cortex has big layer V.
Where is the macula represented?
At the very posterior portion of V1
Pyramidal neurons
Principal output neurons, main axon leaves the cortex, spiny and excitatory (glu)
Non-pyramidal neurons
Interneurons with local projections. Some are inhibitory (GABA) some are excitatory (spiny stellate)
Major subtypes of GABAergic interneurons and where they contact pyramidal cells
Chandelier Cell (at axon inital segment) , Double Bouquet (At dendritic shafts and spines), Basket Cells (at cell bodies)
Cell type implicated in epilepsy?
Large Basket cell
Function of the monoaminergic projections from brainstem?
Attention, mood, affective state, sleep, vigilance
Function of the cholinergic projections from the nucleus basilis?
Cognition and learning/memory
Type of circuit with
1) gaba
2) glu
3) monoamines
1) local interneurons
2) cortical-cortical, thalamo cortical
3) diffuse modulatory control from brainstem to cortex
Two streams of vision
What (inferotemporal stream) V1-> V2 -> V4 ->Temporal. Cells selective for pattern and shape.
Where (parietal stream), cells selective for motion, rotation, etc.
Face recognition
Fusiform gyrus
Visual agnosia
non-aphasic person can’t recognize a stimulus, even though they can’t see it
Prosopagnosia
Can;t recognize faces. Correlated with damage to occipitotemporal area
Visual object agnosia
Inability to recognize general classes of objects
Balint’s syndrome
Optic ataxia (can’t target point given visual guidance), ocular ataxia (inability to shift gaze at will towards new stimuli), simultanagnosia (perception and recognition of only parts of the visual field)
Function of the pre-frontal cortex
Working memory, planning, executive function, top-down cognitive control, modifying the rules, response inhibition
Convergence of modalities in the prefrontal cortex
Input from auditory/somatosensory/motor/visual/medial temporal structures, then integrated by the PFC
Cognitive test for DLPFC
Delayed response test, neurons from PFC fire during the delay signifying that thinking is occuring. Also, neurons fire in the region of the brain that control either where or what.
Where does activity migrate after DLPFC and visual cortex active?
Migrates back to premotor cortex, and along the what/where streams
What happens in auditory delay test?
PFC active, and Heschel’s active
What is organized pre and post central sulcus
Pre: executive/motor
Post is sensory/perceptual
Where are “Rules of the Game” encoded?
PFC
Wisconsin card sorting
Patients with damage to PFC can’t change the rules.
