12. Cerebral cortex Flashcards
temporal:
define
relating to time;
has more to do with temporal region of the skull;
where the hair start to turn gray, denoting the passage of time
neocortex:
definition, % of cortex
“new, young”; newest evoluntionarily
90% of cortex
paleocortex:
define, location, function
“ancient, primitive”;
location: ventral surface
function: olfactory cortex
archicortex:
define, function
“primary, early, chief”; oldest evolutionarily;
function: hippocampal portions of limbic system
as mammals get more complex, which subdivision of the cortex has more “real estate” devoted to it?
what other effect does this have?
isocortex (neocortex);
sacrfices some of the olfactory capability of “lower mammals”
what are the 6 layers of the cerebral cortex?
the cortex itself is very thin (only about 2.5 mm thick)
- molecular layer (most superficial)
- mostly cell processes (dendrites)
- few granule (Stellate cells)
- pyramidal and granular levels
- multiform layer is deepest
- projects to thalamus
direction of most information traveling in the cerebral cortex?
most traveling vertically;
granule (stellate) cells help information move horiztonally
describe layers 2-5 of cerebral cortex
- alternating pyramidal and granular layers
characteristics of pyramidal layers (external - III and internal -V)
-
pyramidal: chief cortical afferent cell;
- apical dendrites from surface &
- basal dendrites: horizontal;
- w/ axons leaving the cortex for other cortical areas or subcortical nuclei
characteristics of granular layers (II-external) and (internal-IV)
granular: cortical interneurons;
- especially numerous in sensory regions;
- short dendrites and axons (extending in all directions)
- input from the thalamus
intracortical fibers:
location, characteristics
- located superficially (layer I of cerebral cortex); just deep to the arachnoid and pia mater
- ipsilateral: travels shorts distances w/in the same hemisphere
cortical columns:
define
vertically oriented functional units of the cerebral cortex;
each is a few mm in diameter and contains
thousands of neurons that are interconnected in the vertical direction
association fibers:
define, characteristics
- layers II & III
- ipsilateral
- connects adjacent gyri or lobes
arcuate loop:
define
association fibers connecting adjacent gyri
arcuate fasciculus:
define
association fibers connecting frontal and temporal lobes
commisural fibers:
characteristics
- cross midline
- connect Right and Left homologous areas
- 2 major commissural fibers bundles:
- anterior commissure
- corpus callosum
corpus callosum:
define and components
- thick and tough “like a callus” body; fiber body, connects cerebral hemispheres; just deep to cingulate gyrus (involved in Papaz circuit - memory formation in limbic system)
- components
- Rostrum: “beak”
- Genu: “knee”
- Trunk:
- Splenium: “bandage”
anterior commissure:
function
connects right and left TEMPORAL lobes
trunk of corpus callosum connects…
connects R & L frontal and parietal lobes
in what view would you find both the genu and splenium of the corpus callosum connecting the two?
in a horizontal view;
how connections between homologous areas L and R thru the corpus callosum
cortex has been removed from this image:
what structure is transmitting fibers from side to side?
corpus callosum
projection fibers:
characteristics
- cortex <–> subcortical nuclei
- two directions
- corticofugal
- corticopetal
corticoFUGAL vs corticoPETAL
- corticoFUGAL: efferent to nuclei
- corticoPETAL: afferent from thalamus
pathway of projection fibers?
pass thru subcortical areas (such as internal capsule)
located b/w thalamus and corpus striatum
w/in the internal capsule, what are the different limbs?
- ANTERIOR limb
- Genu
- POSTERIOR limb
- Retrolenticular limb
- optic radiation fibers
- Sublenticular limb
- auditory radiation fibers
where are the optic radiation fibers found in the internal capsule?
in the retrolenticular limb
think: RETRO glasses for optic radiation?
where are the auditory radiation fibers found in the internal capsule?
in the sublenticular limb:
think SUBwoofer speakers = SUBlenticular = AUDITORY radiation
components of ANTERIOR limb
-
corticofugal: motor tracts; darker matter
- to corpus striatum
- to pontine nuclei
-
corticopetal:
- thalamic nuclei –> cortex
components of genu
(of internal capsule)
- corticofugal: corticobulbar tract
-
corticopetal: motor thalamus; (VA/VL) - cortex
- hitting the PEDAL = motor accelerates
posterior limb: components
- somatotopic organization
-
corticofugal:
- these are the axons of the upper motor neuron
-
corticopetal:
- thalamic radiations