Flashcards in The Brain II Deck (53):
where is the neocortex? How many layers does it have?
it forms the majority of the cortex and it has 6 layers
list the layers in order of closest to pia mater till the one closest to subcortical white matter
I molecular, II external granular, III small pyramidal, IV internal granular, V large pyramidal, VI multiform
the I molecular layer is aka?
the plexiform layer. It has the least neurons
are most of the cells in the neocortex inhibitory or excitatory?
they are excitatory, (this is opposite to cerebellar cortex)
what are the 2 kinds of cortical neurons?
the pyramidal and the non-pyramidal neurons.
the spiny dendritic neurons are?
what are chandelier neurons?
the branches of the axon embrace the pyramidal cell axons
what are basket neurons?
the branch of the non-pyramidal cell branch onto the proximal part of the dendrites
where do non pyramidal cells originate from?
the ganglionic eminence
where do pyramidal cells originate from?
how do pyramidal cells reach the cortex?
they perform interkinetic nuclear migration. hey move from the basal/Pial side to the ventricular/apical side
what are radial glia?
they are used as pole for the cells ,which are leaving the ventricular side, to wrap around and move up and down. They are both a migrating scaffold but also a proliferative precursor
the neurons which are on the radial glia can be called? They need which chemicals?
locomotion neurons, Multipolar neurons. Need Cdc42, Rac1, RhoA
which gene when mutated drastically mutates the cortex formation?
the Lis1 gene. A microtubule 'cage' surrounds the nucleus and links it with the centrosome using the microtubule network. The lissencephaly 1 protein (LIS1) functions as a bridge
what allows cells to move?
the link between the nucleus, the microtubule network and the centrosome to enable movement.
REFER TO SLIDE
the walls of the neural tube are divided into?
the innermost (ventricular) ependymal layer, then mantle, marginal layer. In the center is the canal
explain the inside out formation of the cortical layers
there is the first wave migration of neurons and glia which exit the ventricular layer and they move and form the preplate area which is very superficial. These neurons start to extend some axons and they form an intermediate zone.
The second wave migration: it leads to formation of cortical plane, and causes the preplate to divide into an upper marginal zone and lower subplate.
Last: the later born neurons migrate through the intermediate zone, subplate, lamina V/VI and then they form lamina II,III,IV
the subplate forms which layer?
where is the subventricular zone?
it is below the ventricular layer. It is an accessory germinative layer
what becomes the white matter?
the intermediate zone, MZ,CP,SP
note that the first born neurons in the lamina I ?
disappear and so does the subplate
what is reln?
it is a protein that is produced by cajal retzius cells, they are already present in the preplate before the first wave
what is the tangential migration and who performs it?
it is the outward and tangential migration of neurons and glia, it is done by the cells from the ganglionic eminence
which layer is targeted for thalmic projection? Which is the source for centrifugal cells
layer IV, layer V
what are the 3 layers of the cornu ammonis?
polymorph, pyramidal, molecular layer
what are the 3 layers of the dentate gyrus
the polymorph, the granular, molecular
the paleocortex is close to the ?
what is the uncus?
it is the hooked part of the temporal lobe
name the structures found in/near the anterior horn of the lateral ventrical
septum pellucidum, forceps minor, rostrum of corpus callosum, caudate nucleus, tapetum of corpus callosum, thalamus (forms the floor)
what structures are near/in the posterior/occipital horn of the lateral ventrical?
the tapetum, forceps major, note that this is embedded in the white matter of the occipital lobe
name the structures in the inferior horn of the lateral ventrical?
the hippocampus, amygdala, tail of caudate nucleus, stria terminalis, associative fibers
name the parts of the diencephalon
the thalamus (metathalamus), hypothalamus, epithalamus, subthalamus
how can we see the epithalamus and the thalamus
by removing the corpus callosum and the body of the fornix
what is the point where the two thalamus lobes meet
the interthalmic adhesion
what it the large posterior part of the epithalamus and thalamus called
what is the structure on the roof of the third ventrical?
the tele coroidea
what is the stria medullaris?
the connection between the limbic system
what is the foramina of Monroe?
the communication between the third and lateral ventrical
The epithalamus has which glands. What happens as we age?
It has the pineal glands, which produce melatonin and calcify as we age
When the pulvinar is displaced,what do we find under It?
The lateral and medial geniculate bodies : The metathalamus
Where is the trigone of habenular? What is It?
It is in the epithalamus, it contains the habenular nuclei, which function to help limbic system communication. Note that when we move anterior to it we find it's attachment to the stria medullaris
Where is the habenular commisure
At the epithalamus. It contains the habenular commisure and the posterior commisure
What is the purpose of the posterior commisure
It connects the 2 mesencephalon, it is involved in the papillary reflex, it connects the 2 colliculi (superior and inferior) , connects the prefectal nuclei.
Where is the prefectal area
It is the transition area from the base of the brain to the midbrain
The presence of which structure can explain why when a light is shone into one eye,both pupils constrict
The posterior commisure
Where is the subcommisural organ
It is in the wall of the mesencephalic aqueduct where it enters into the 3rd ventricle
What is the purpose of the subcommisural organ. An error in it leads to what illness?
It secretes a protein that keeps the mesencephalic aqueduct open and promotes neurogenesis, and binds to compounds that need to be cleared from the CSF.
It leads to congenital hydrocephaly : the CSF produced in the lateral ventricles and the 3rd ventricle cannot be drained through the fourth ventricle into the cisterna magna and eventually the sub arachnoid space
Explain the division of the thalamus
It is made mostly of Gray matter, yet it has 2 strips of white matter that help it's division. The internal lamina medullary, and the external medullary lamina.
The internal lamina is Y shaped, in the V of the Y we have the anterior thalamic nuclei.
Medial to the Y we have the median ( closer to thr other thalamus) and medial nuclei. And lateral to the Y is the lateral nuclei which is divided into many other sections .
Lateral to the external medullary lamina we have the reticular nucleus
What are the 3 types of nuclei in the thalamus
The specific relay nuclei, the association nuclei, the non specific nuclei
Refer to slide 69
For matching on thalamic region and type of neurons
What are thalamic peduncles
They are part of the internal capsule, and the corona radiata. It can be superior, inferior, posterior, anterior