Cerebral Cortex Flashcards
Cortical cells
-contain glutamate
-are excitatory
-are projection neurons, and
their major axons enter the white matter
-The brain regions targeted by pyramidal cells are
based in part on their laminar position
Cortical: Cells in deep layers tend to project to ____
targets.
-subcortical
Layer 6 cells tend to project to the _____
:
-thalamus, mainly to specific relay nuclei.
Cortical: Cells in superficial layers tend to project to _____
-other cortical areas
Cortex: Both layers 2 and 3 have
_____projections (same hemisphere).
-associational
Which layer of cortical neurons are the main source of callosal axons that travel to the opposite hemisphere?
- Layer 3
Commissural projections are homotopic
if they innervate the same cytoarchitectonic division on the opposite side
Commissural projections are heterotopic
-if they innervate a different cortical division.
What correlates to the complexity of the computational processes carried out by pyramidal cells in particular regions and species?
-dendritic branching and spine density
stellate cell
- is the only known type of excitatory interneuron in the cortex
- It is a modified pyramidal cell that loses its extrinsic axon in the course of development
chandelier cell
- makes local connections
- synapses onto the axon initial segment of pyramidal cells
- most powerful of the interneurons
double bouquet cell
-gives rise to vertically directed axons that target the distal dendrites of pyramidal cells and non-pyramidal cells across multiple layers.
basket cells
-inhibitory interneurons whose axons spread horizontally and synapse onto the soma and proximal dendrites of pyramidal neurons in the same layer
where do most of the synapses on cortical pyramidal cells come from?
-neighboring stellate (+) cells and pyramidal neurons
where do most of the excitatory drive to basket cells arose from?
-intrinsically from pyramidal neurons
what role do basket cells play in the cortical connectivity
-basket cells inhibit other pyramidal neurons providing necessary connections for: feedback, feedforward, and lateral inhibition
what role do the double bouquet cells play?
- their activation is unknown
- they synapse onto distal dendrites of both pyramidal neurons and other interneurons
in sensory cortices, the major excitatory input is from
- specific thalamic nuclei
- these terminate in layer 4 on stellate or pyramidal cells with some sparse inputs to basket cells
cortico-cortico afferents
Ascending or feed forward projections generally originate in layer ___ and terminate in layer ___
-originate layers 2/3
terminate in layer 4
feedback projections generally originate in layers __ and terminate in layers __
- originate from layers 5/6
- terminate in layers 1 and 6
intralaminar thalamic afferents synapse primarily within layer __
-1
and they innervate the distal dendrites of pyramidal cells
intralaminar thalamic afferents
-increase the overall excitability of cortical neurons to promote a conscious state that is able to process information
cortical regulation of complex behaviors involves ____ pf separate stimulus features through ___ pathways
- parallel processing
- divergent
prefrontal cortex
- sits at the top of both the sensory and motor hierarchies
- it is involved with decision making, executive functions, and future planning
multimodal association cortices
-limbic
prefrontal
parietal-temporal-occipital
the parietal-temporal-occipital association corticex
- occurs at the interface of higher order somatic, visual, and auditory regions
- linking of multimodal information enhances the performance of complex tasks
optic ataxia
- difficulty in using visual guidance to perform motor tasks or to reach for and grasp objects
- can result from damage to parietal-occipital association cortex
astereognosis
- the inability to recognize objects based by touch based on their texture, size, and weight
- result of parietal-temporal-occipital cortex damage
apperceptive agnosia
- inability to distinguish visual shapes
- associated with trouble recognizing, copying or distinguishing between different visual stimuli even though they can name it
- occurs from parietal-temporal-occipital cortex damage
associative agnosia
-patients can recognize the spatial aspects of objects i that they can copy them, but they cant name them
hemi-neglect
- right parietal temporal-occipital association damage
- this is a tendency to ignore sensory information from the opposite side of the body
- this neglect will be both visual and somatosensory
- neglect also affects information that is called to mind from memory
cerebral lateralization
-hemispheric dominance of some cortical functions
Language is lateralized in the brain
-it is developed in the left hemisphere in most people
-two major centers of language are recognized:
Broca’s and Wernicke’s
Broca’s area
- the anterior speech area
- located near the premotor cortex
- important for generation of speech
Wernicke’s area
- is in the temporal lobe
- important for the comprehension of speech
- communicates to Broca’s area in processing both written language and spoken language
Expressive aphasia
- results from damage to Broca’s area
- impaired speech
- some even have agraphia, but language comprehension is alright
sensory (receptive) aphasia
- damage to Wernicke’s area
- spontaneous speech is fluent, but words and sentences are inappropriate
- some people even express alexia
