Cerebral Cortex: Gondre-Lewis Flashcards
What is the Cerebral Cortex?
-external gray matter of the telencephalon -organized into layers -Necessary for higher cortical function. -Highest level of processing of information entering the brain -Serial processing between different parts of the cortex. (Primary, Secondary, etc.)
90% of the cerebral cortex is what?
Neocortex with 6 layers -has gray matter which is the cortical matter grouped neuronal cell bodies bunched together has basal ganglia/basal nuclei ?????
What is the most primitive layer of the cerebral cortex?
Archicortex “ancient”which has 3 layers and includes: -dentate -hippocampal gyri
Describe the paleocortex “old” philogenetic catergory of the cerebral cortex.
has 3-5 layers and includes: -rostral insular cortex -uncus -anterior perforated substance -primary olfactory cortex -entorhinal cortex occupies very little space
What is the gray matter of the cerebral hemisphere?
Cerebral Cortex Basal Nuclei
What is the white matter of the cerebral hemispheres?
Projection Fibers Commissural Fibers Association Fibers – short and long -Corpus callosum: a commissural axon -Internal capsule: projection fibers that pierce through the basal nuclei -Anterior commissure
Going micro to macro Cerebral Cortex –neuronal circuitry
Cerebral cortex has neurons and glia. NEURONS: projection neurons -other areas of cortex (ipsilateral, contralateral, or lateral) -subcortical areas interneurons (local circuit neurons) are GABAnergic neurons????? GLIA: -Oligodendrocytes -Microglia -Astrocytes
Relationship of GABA-ergic neurons with pyramidal neurons
-gabaergic control of pyramidal cells -Pyramidal neurons can be excited and inhibited by the neurotransmitters glutamate and GABA, respectively. GABA is the chief inhibitory NT
Dendritic arbors and spines
A dendritic spine (or spine) is a small membranous protrusion from a neuron’s dendrite that typically receives input from a single axon at the synapse. Dendritic spines serve as a storage site for synaptic strength and help transmit electrical signals to the neuron’s cell body -with intellectual disabilities you have decreased or fewer dendritic spines -some diseases have long and thin dendritic spins that still do not have capability to function
Different types of GABAergic interneurons
modulating behavior of the pyramidal cells -Chandelier cell -Double Bouquet Cell Large Basket Cell
Most projection neurons are
pyramidal cells which are excitatory
Most interneurons (local circuit neurons) are
non-pyramidal cells and are inhibitory (GABA)*
What are barbiturates and benzodiazepines?
-drugs that suppress the CNS and act as depressants -uses include sedation (anesthesia), anticonvulsants (seizure), antixiolytics (for anxiety) -are agonists at ionotropic GABA receptors
Area 17
lingual gyrus (upper visual) , cuneate gyrus (lower visual), calcarine fissure The visual cortex of the brain is a part of the cerebral cortex that processes visual information. It is located in the occipital lobe.
Brodmann area 4 refers to
the primary motor cortex of the human brain
What areas are primary sensory?
somatosensory: 3, 1, 2 Vision: 17 Auditory: 41
What areas are secondary sensory?
Vision: 18 Auditory: 42 Secondary motor: 6 Motor and speech: 44 and 45 ????
Describe the 6 layers of the neocortex.
Layers 1–>6 from the pial surface and down Layers I, II, III -Project to and receive input from intrahemispheric and interhemispheric cortex Layer IV -Receives Thalamocortical input Layer V -Projects to subcortical regions Layers VI -Projects to Thalamus
The thickness of the 6 layers varies according to function.
layer 4, which receives inputs from thalamus, is very thick in primary sensory but thin in primary motor areas. layer 5, which projects to the brainstem/spinal cord, is very thick in primary motor but thin in primary sensory areas.
What are the different types of fiber bundles coursing through the cortex?
-short U-fibers -longer associational bundles -commissures inclusive of corpus callosum and anterior commissure
Short U-Fibers Connect?
Adjacent Area of Cortex
Long Associational Bundles Connect?
Cortical Areas That are Far Away
Commissures connect?
Corpus Callosum: connects the right and left cerebral hemispheres; connects the left and right sides of the brain allowing for communication between both hemispheres; largest fiber tract (splenium, body, genu) Anterior Commissure: connecting the two temporal lobes of the cerebral hemispheres across the midline, and placed in front of the columns of the fornix; interconnects the right & left temporal lobes and olfactory tracts
VPL nucleus: ventral posterolateral nucleus (VPL) is a nucleus of the thalamus LGN goes to primary visual cortex MGN goes to primary auditory cortex
The VPL receives information from the neospinothalamic tract and the medial lemniscus of the posterior column-medial lemniscus pathway. It then projects this sensory information to Brodmann’s Areas 3, 1 and 2 in the postcentral gyrus. Collectively, Brodmann areas 3, 1 and 2 make up the primary somatosensory cortex of the brain.
The thalamus is a sensory relay center between the brain stem & cortex.
Specific thalamic nuclei project to specific areas of cortex
Projection Fibers
Internal Capsule – Projections fibers connecting cortex to subcortical structures Internal Capsule- A compact bundle of fibres through which the following fibers Pass: Thalamocortical fibres Corticothalamic fibres Corticopontine fibres Corticobulbar fibres
What are the 3 arteries that supply the cerebral cortex?
- posterior cerebral 2. middle cerebral (can be seen on the lateral face of the brain hemisphere) 3. anterior cerebral
Think of the arteries as 3 water systems: Watershed zones
A watershed zone is an area of brain farthest from direct perfusion with blood supply by the major cerebral arteries. Watershed strokes result from hypoperfusion (a lack of blood flow). May be caused by congestive heart failure, atherosclerosis of the carotid arteries and hypotension.
Advantage of a watershed areas
watershed areas are often spared following obstruction of a single cerebral artery
What part of the brain is the cerebral cortex apart of?
Gray matter of telencephalon
What are the components of the archicortex?
Hippocampus
dentate
*3 layers
What are the components of the paleocortex?
Rostral insular cortex
Uncus
Anterior perforated substance
Primary olfactory cortex
Entorhinal cortex
*3-5 layers
What are the components of the neocortex?
This is the new cortex made up of 6 layers.
__________: which are primary olfactory areas at thebase of the ventral surface of the forebrain
Anterior perforated substance
Lesions of basal ganglia are characterized by disorders of __________, either too much or too little.
movement
Identify important structures of the cortex.
Corpus collosum
Internal capsule
Anterior white commisure
The _____________ cells is modulating the input to the dendrites on the pyramidal cell. ____________ cells are talking to several pyramidal neurons that could be in this column.
double bouquet cell; Basket cells
Grey matter of cerebral hemispheres
Cerebral cortex
Basal nuclei
Dendritic spines are directly related to ______________
intellectual capability.
i.e. FRAGILE X
Most projection neurons are ___________ which are excitatory.
Most _______________ are non-pyramidal cells and are inhibitory (GABA)*
pyramidal cells; interneurons (local circuit neurons)
Barbiturates and benzodiazepines are ______________(agonist/antagonist) at ionotropic GABA receptors.
Agonist
**Because they suppress cortical activity, they are used as antixiolytics (anxiety) and anticonvulsants (seizure).
Primary visual cortex is the occipital lobe but the first place it comes in is the ___________, ________, and ____________.
cuneus gyrus, the lingual gyrus, and calcarine fissue.
___________ is really the center of your visual field.
Calcarine fissure
What are brodmann’s area for primary sensory?
- Somatosensory- 3, 1, 2
- Vision - 17
- Auditory - 41
What are brodmann’s area for secondary sensory?
Vision 18
Auditory 42
What is broadman’s area for primary motor?
Primary Motor 4
What are broadman’s areas for secondary motor and motor speech?
Secondary Motor- 6
Motor Speech -44 & 45
What are the functions of the 6 layers of the neocortex?
Layers I, II, and III
•Project to and receive input from intrahemispheric and interhemispheric cortex
Layer 2 and 3 are intra and interhemispheric small pyramidal neurons
Layer IV
•Receive thalamocortical input
Layer V
- Projects to subcortical regions
- Contains large pyramidal neurons that project from the cortex to subcortical regions
Layer VI
•Projects to the thalamus
Layer _________ is very thick in primary sensory but thin in primary motor areas.
4
*Sends from thalamus to cortex
Layer __________, which projects to the brainstem/spinal cord, is very thick in primary motor but thin in primary sensory areas.
5
NOTE: If you’re an association area where you receive and send out info, you’ll have fairly equal areas of 4 and 5.
Fibers in the corpus collosum come from layer ______ neurons
3
Arucate fasciculus
- It’s part of the longitudinal fasciculus that connects the front and back
- It connects Wernicke’s to Broca’s area
Different parts of the corpus collosum
•Splenium- has info from the occipital cortex
•Genu- The basal ganglia connects through the genu
•Body- Has somatosensory and motor
So __________is radiating fibers in the cortical region that radiate down through the pyramids to act on lower MNs, coming from layer _________to act on the part of the body that cortical area is associated with.
corona radiata; 5
This shows the corticospinal tract fibers- these are the same ones that are coming from layer_________.
5
____________ nucleus projects to the primary visual cortex
LGN
The cerebral cortex is supplied by three arteries:
- posterior cerebral
- anterior cerebral
- middle cerebral
Middle cerebral artery courses through the ____________on the side, it also has collaterals that feed the frontal and lateral lobes.
sylvian fissure
There’s also the posterior cerebral arteries coursing towards the back meant to feed the ____________
occipital lobe
The ____________ artery services the primary auditory cortex, the insula, the basal ganglia, Wernicke’s area, primary and somatosensory presentation of the face and hand. It also services Broca.
middle cerebral
Watershed Zones of the Major Cerebral Arteries
Depending on blood flow, you may have redudancy in terms of blood and oxygen to these regions- the posterior cerebral artery receives blood from the vertebral artery, so even if the internal carotid is blocked you have another source and can bypass it. However, the anterior cerebral artery may not receive a strong enough input since it’s source is the internal carotid artery- you could then have tissue death.
If there is damage to the ACA-MCA watershed infarct, what part of the patient will be affected?
The upper trunk area would be affected.
