Cortex Flashcards
What are the different architectural areas of the cortex?
Which accounts for the majority of the cortex?
Neocortex (95%)
Allocortex
Juxtallocortex or Periallocortex
Subcortical
What are the layers of the neocortex?
What information does each one send or receive?
Molecular - input from and output to other areas of cortex (association and commissural fibers)
External granular - input from and output to other areas of cortex (association and commissural fibers)
External pyramidal - input from and output to other areas of cortex (association and commissural fibers)
Internal granular - input from thalamus
Internal pyramidal - output to striatum, brainstem and spinal cord
Polymorphous - output to thalamus
What is the difference between granular and agranular parts of the cortex?
What are some examples of granular cortex?
What are some examples of agranular cortex?
Granular has well-developed layer IV and agranular does not
Granular - primary sensory cortex, prefrontal cortex (BA 8, 9, 10)
Agranular - primary motor cortex (BA 4), premotor cortex (BA 6)
Commissural Fibers:
What are commissural fibers made up of?
What do commissural fibers do?
Name specific locations of commissural fibers.
Primarily axons from layers II and III Connect homologous areas of two hemispheres Corpus callosum Anterior commissure Posterior commissure
Corpus Callosum:
What does the genu connect?
What does the body connect?
What does the splenium connect?
Genu - anterior frontal lobes
Body - posterior frontal lobes, all parietal lobes and superior temporal lobes
Splenium - occipital lobes
What does the posterior commissure connect?
Pretectal nuclei important for pupillary light reflex
Projection Fibers:
What do projection fibers connect?
What direction is the signal traveling?
What are the parts of the internal capsule?
Cortex to subcortical, brainstem and spinal cord targets
Up and down
Anterior limb, genu, posterior limb
What fibers are in the anterior limb of the internal capsule?
What do fibers of the anterior limb of the internal capsule connect?
corticofugal fibers and thalamocortical fibers
Medial and anterior nuclei of thalamus to frontal lobes
What fibers are contained in the genu of the internal capsule?
Corticobulbar fibers
What fibers are contained in the posterior limb of the internal capsule?
Mainly corticospinal fibers
What are the stages of cortical development?
When do they occur?
Neurogenesis - prenatal
Migration - prenatal
Arborization - prenatal through early adulthood
Myelination - prenatal through early adulthood
Synapse formation - continues throughout life
What is the resulting pattern from migration of neurons along radial glia?
Inside-out lamination - newer neurons end up superficial to older, deeper neurons
What is filamin?
What is filamin responsible for?
Actin-binding protein
Signaling initiation of migration of neurons (getting new neuron on radial glia)
cc: periventricular heterotropia (FLNA gene mutation)
neurons that should have emigrated remain collected near walls of ventricles
females are only mildly compromised with late onset epilepsy
Males die en utero
What is doublecortin (DCX)?
What is doublecortin responsible for?
Microtubule-associated protein
Maintains proper migration (keeps new neuron on radial glia)
cc: Lissencephaly– smooth brain & pachygria– few gyri(males)
cc: subcortical laminar band herotropia – bad of grey matter that terminated prematurely is found underneath cortex within white matter (females)
What is reelin?
What is reelin responsible for?
What cells secrete reelin? What are they?
Where does reelin accumulate?
Lis1
Extracellular matrix protein
Cell-cell interactions and termination of migrating neurons
Cajal-Retzius cells - early-born neurons in layer I just below pial surface
Norman Roberts Syndrome – inverted cortical lamination (younger neurons deeper to older neurons)
