cerebral cotex Flashcards
what makes up the cerebral cortex phyiscally
sheets of neurons(gray matter), in a 2ft squared area,2 -5 mm thick
weight of cerebral cortex
half of brains weight
neurons in the cerebral cortex
25-50 billion
axons in the cerbreal cortex
100,000 km
synapses in the cerebral cortex
10^14
role of the cerebral cortex
language, abstract thinking, adaptation to environment, planning, art…
what makes up the cerebral cortex
neocortex ( the evolved new part of cortex) 95% of total cortex
layers of the cerebtral cortex
6 layers
layers of paleocortex
3 layers
layers of archicortex
3 layers
role of paleocortex
olfaction
the paleocortex lies where
over the uncus
what makes up the archicortex
most of the hippocampus
where do layers of the neocortex sit
layer run is right under the pia mater and layer 6 is right above the white mater
what makes up most of the cells of the neocortex
pyramidal cells
morphology of the pyramidal cells of the neocortex
pyramidal cell body, with apical dendrites that goes straight up to the cortex talking to neurons along the way
basal dendrites that basically go out laterally to talk to nerons in the same layer
axon goes out to talk to other parts of brain and in the cortex e
functional layers of the neocortex are arranged how
vertically
nonpyramidal cells of the brain
Basket cells, Candle Cells, and Bipolar cells and more
synapses of pyramidal cells of the cortical neuron
excitatory (glutmate) synapses
The preferential siteof excitatory synapses
Dendritic spines
why dod dendritic spines apear
selectively modified asa result of learning
what do changes in dendritic spine configurations lead to
change in electrical properties and in turn synapse effeciency
poor dendritic spine formation leads to
intellectual disability: autism, fragile X syndrome
neruotransmitter of non-pyramidal neruons
non-excitatory (inhibitory)- GABA
axons of non-pyramidal cells
short and remain in the cortex
roll of non-pyramidal cells in the cortex
principle interneurons of the cortex
nonpyramidal cells with spiny denrites, generally excitatory, and glutamineric synapses with pyramidal cell
Spiny stellate cells
were do spiny stellate cells recieve their synapses
afferednt inputs from thalamus and other cortical areas
nonpyramidal cells with non-spiny dendrites, receives recurrent collateral branches from pyramidal cells, inhibiotry(GABAergic synapses with pyramidal cells)
Smooth stellate cells
activity of Smooth stellate cells
silence weakly active cell columns in the cortex (similar to focusing action)
nonpyramidal cells loacted maining in the outer layers, containing peptide co-release with GABA
bipolar cells
the precentral gyrus is what
the somatic sensory cortex
the postcentral gyrus is wat
the primary motor cortex
what is found in layer 1 (molecular) layer of the cortex
ends of pyramidal cell apical dendrites
distal ends of some thalamocortical(intralaminar nuclei) axons
what is found in layer 2 of cortex (outer granular)
small pyramidal and stellate cells
what is found in lay 3 of cortex (outer pyramidal)
medium sized pyramidal and stellate cells
what is found in layer 4 (inner granular) cortex
stellate cells receiving thalamocorotical axons (relay nuclei)
what is found in layer 5 (inner pyramidal) cortex
large pyramidal cells to striatus and spinal cord
what is found in layer 6 (fusiform) cortex
modified pyramidal cells porjecting to the thalamus
mylin bands of the cortex
outer band of baillarger
Inner band of Baillarger
5 sources of afferents to the cortex
Association fibers(long and short): Commissural Fibers: Thalamocortical Fibers: Non-Specific thalamocortical fibers Cholinergic & aminergic
association fibers fiber in the cortex travel from
from small and mdeium sized pyramidal cells in other parts of ipsilateral cortex
commissural fibers in the cortex travel from
medium sized pyramidal cells via corpus callosum or anterior commissure from corresponding contralateral cortex
thalmocortical fibers in the cortex travel from
from relay or association nuclei
non-specific thalamocortical in the cortex fibers travel from
from intralaminar nuclei
cholinergic and aminergic fibers in the cortex travel from
basal forebrain, hypothalamus(tuberoinfuncibulum), brainstem (midbrain raphe, LC)
what are all efferents
pyramidal cell axons
excititory
short association efferents from the cortex connext
sensory cortex to the motor cortex
long association efferents connect
prefrontal cortex to the motor cortex
efferent commisural fibers travel
from contralateral cerebrum via corpus callosum and anterior commissure
what makes up the largest input to the basal ganglia
fibers from primary sensory and motor cortex
the thalamus receives input from what
all of the cortex
efferents from the cortex
association (long and short)
commissural fibers
fibers from primary asensorya nd motor cortex
thalamus
corticopontine, corticospinal,corticobulbar
where in the cerebral cortex do afferents from the cerebral cortex go
Layers 2 and 3
where do afferents from the thalamic relay nuclei go in the cerebral cortex
middle layers sensory to IV
where do thalamic intralaminar nuclei afferents go in the cerebral cortex
Layer VI
what layer of cortex contains corticothalamic fibers
VI
what layer of cortex is the major source of corticostriate fibers and also to BS and SC
V
what layer of cortex is the major source of cortico-cortical fibers
III
what interconnects the cerebral hemisphers
Commissures
the predominant interconnextion between hemisphers
Corpus callosum
what interconnexts temporal lobes(inferiorly) and the anterior olfactory neculei
anterior commissure
the largest bundle o fibers in the brain that interconnects the hemispheres
Corpus Callosum
what parts of the brain do NOT receive commissural fibers
hand area of somatosensory and motor cortex
parts of primary visual cortex
disconnection syndromes are caused by
white matter damage
also stokes
disconnection syndromes cause
alexia without agraphia (can write but unable to read, cannot read words even they wrote, also homonymous hemianopia)
how does alexia without agraphia occure
languages area on left isolated from all visual input
leeft visual cortex damaged by stroke
right visual cortex intact but corpus callosum damaged
language areas intact, so speech is unaffected
what do association bundles connect
interconnects areas of 1 hemisphere
shape of short association bundles
U-fibers
long association bundles
travel to different lobes
Association bundles
Superior longitudinal (arcuate) fasciculus Superior occipitofrontal Fasciculus Inferior occipitofrontal fasciculus Cingulum Uncinate Fasciculus
ranular vs granular cortex
Agranuluar: primary motor cortex/precentral gyrus
granular: somatosensory cortex/postcentral gyrus
how many pyramidal cells do areas that send off long axons have
more pyramidal cells
primary sensory areas of the neocortex project to____ so they lack____ and have fewer____
nearby cortex
long axons
pyramidal cells
distribution of granuluar and agranular cortex
irregularly distributued
the areas of the neocortex is characterized how
brodmann did it with 44 areas, with imprecise boundaries
relation of granular strucutre and function
not tightly correlated with function
relation of brodmann area size between individuals
cortical volume constant
large variation in brodmann area sizes among individuals
types of cortical regions
primary motor areas
Primary sensory areas
Association areas
Limbic areas
cortical region that gives rise to much of the corticospinal tract
Primary motor area
cortical region that receives info from thalamic sensory relay nuceli
Primary sensory area
how is the sensory area of the brain organized
topographical organization (body surface, rnage of frequencies, visual world are mapped on cortical surface) highly sensitive areas(fingers, fovea) have large cortical representations
roll of parietal lobe, primary somatosensory cortex(postcentral gyrus (3,1,2)
initial processing of tactile and prorprioceptive info)
roll of parietal lobe, inferior parietal lobule are 1 hemisphere (left)
language comprehension)
roll of parital cortex minus the inferior parietal lobule of 1 hemisphere(left) and the primary somatosensory cortex
complex aspects of spatial orientation and directing attention
location of the primary visual cortex
in the banks of calcarine sulcus of the occipital lobe
roll of the visual association cortex
higher order visual processing
location of the visual assocation cortex
occipital lobe
bilateral injury to the inferior occipital lobe leads to
color blindness
bilateral injury to the occipital temporal junction leads to
motion blindness
the thin stripe of myelin in the primary visual cortex, aka striate cortex
line of gennari
what does the striate cortex parallel and where does it extend
calcarine sulcus and extends a bit onto posterior surface
which fibers from the retina cross to the contralateral optic tract
fibers from the nasal half of retina
the optic tract sees what visual field
contralateral
how is depth perception gained
comparing areas of both retinas in the chiasm
layers of the Lateral genicular nucleus
6 layers of precise reintotopic arragment
patterning of the lateral geniculate nucleus
same in each layer so any given point in the visual field is represented as a column in all 6 layers
layering of the lateral geniculate nucleus
1,4,6 contraleral eye
2,3,5 ipsilateral eye
what are the parvocellular layers of the LGN
3-6 for color and form
what are the MAgnocellular layers of the LGN
1-2 for movement and contrast
what does the LGN project to
primary visual cortex
fibers representing inferior visual fields project to
most superior in radiations
fibers representing superior visual fields project to
most superior in radiation
how did Dr. Tatsuji Inouye figure out the travel of fibers to the primary visual cortex
used bullet travel with the part of occipital lobe damaged and the visual field that was lost
where do optic tadiations end
reinotopically in the occipital cortex, above and below the calcarine sulucs
(inferior visual fields above )
(superior visual fields below)
location of macula and peripherals fields in the occipital lobe
macula: most posterior
Peripheral: most anterior
roll of the primary visual cortex
breaks visual info into component parts: orientation, color, depth, motion, brightness…
distributes infro to specialized parts of extrastriate cortex
the primary visual cortex processing is an example of
simultaneous, paralel processing
how are neurons arranged
functionally in columns that extend radially through all 6 horizontal layers
what are the neurons of each column of the cortex sensitive to
one modality (modality-specific) such as 1 particular joint, one patch of skin, orientation of an object in visual field…
how are modular collections of neurons aranged in the pimary visual cortex
array of repeated modular collections of neurons in columns
what do columns in one cortical module analyze
all aspects of visual info arriving from discrete areas of the visual field
modules in the foveal parts analyze ____ and that means ____
small areas of the visual fields
fovea has many more modules and therefore better resolution
where does visual processing begin
in the LGN
the ventral stream of visual info contains
parvocellular layers (color, form)- ventral striate cortex
the dorsal stream of visual information contains
magnoceullar layers (location, movment)- dorsal striate cortex
damage to extrastriate cortex can lead to
strange visual deficits: selective deficit in distinguishing colors, motion, and faces
what is found in the temporal lobe
primary auditory cortex
auditory association cortex
Wernicke’s area
where is the primary auditory cortex
transverse temporal gyri, superior surface of the superior temporal gyrus
where is language comprehension done
Wernicke’s area - posterior aspect of 1 hemisphere (left)
where is higher order visual processing done
temporal lobe
what is found in the frontal lobe
Broca’s area
prefrontal cortx
location of broca’s area
inferior frontal gyrus of 1 hemisphere (left)
roll of broca’s area
production of spoken and written language
location of the prefrontal cortex
all of frontal gyrus asside from the inferior
roll of the prefrontal cortex
executive function (personality, foresight, insight)
roll of association areas
mediate higher mental functions (language, art, music, etc)
how much is known about association areas
little, most of knowledge stems from case reports of patients with naturally occuring lessions
functional imaging scans though help advance understanding area
where is the unimodal asssociation cortex
adjacent to the primary area
roll of the unimodal association cortex
devoted to elaborating on business of primary
roll of multimodal association cortex
high level of intellectual functions
where is the multimodal association cortex
inferior parietal lobule
much of frontal and temporal lobes
what is dominant hemisphere
the hemisphere that produces and comrehends language (usually the left)
relation of hemisphere dominance with hand preference
no relation
lateral sulcus on the right and left hemisphere
Right lateral sulcus goes up higher and left lateral sulcus extends more posteiorly
where are cortical language areas found
near lateral sulcus
why does the left lateral sulcus extend further posteriorly than the right
planum temporale is larger on the left
the part of the superior temporal gyrus psoterior to the primary auditory cortex (transverse temporal gyri)
planum temporale
what would happen if you stimulate motor cortex near mouth in the dominant lateral sulcus
produce involuntary grants, vocalizations
what happens if you stimulate areas other than motor cortex near the mouth on the dominant hemisphere
ceases to speak, but still moves mouth
make linguistic errors, fials to find appropriate words
perisylvian language areas
broca’s area in the inferior frontal gyrus (opercular and triangular parts)
Wernicke’s area in the posterior part of superior temporal gyrus, continuing into planum temporale and inferior parietal lobule
the inability to use language, lose the use of or access to symbols humans use as concepts (words)
Aphasia
broca’s and wernicke’s areas provide framework for 2 broad types of aphasia classifed depending on how easily words are produced
nonfluent
Fluent
symptoms of nonfluent aphasia
make few written or spoken words, or get by with just phrases
very difficult to produce words
all detail and meaning in sentence is lost
can comprehend language
cause of nonfluent aphasia
damage in broca’s area
symptoms of fluent aphasia
can write and speak, but words used and sequences of words used in sentences are incorrect little/no linguistic content substitute one letter/word for another make up new words difficulty in language comprehension
cause of fluent aphasia
damage of wernicke’s area
making up new words
neologisms
subsitute one letter or word for another
paraphasia
damage to broca’s area leads to
deprive motor areas of ability to generate language (muscle function normally for other activities though)
comprehension of language unaffected
damage to wernicke’s area leads to
broca’s area is unchecked
words are generated with no meaning
interconnects broca’s and wernicke’s area
arcuate fasciculus
language with the right hemisphere
the emotional and linguist content is given rhythm (musical elements)
the musical aspects of speech
prosody
what produces prosody
right inferior frontal gyrus
motor aprosody leads to
cant convey authority, anger… in speach
where is the comprehension of prosody done
right posterior temporoparietal region
sensory aprosody leads to
difficulty comprehending the emotional content of speech from others
where are the association areas
posterior to primary somatosensory cortex
what are the unimodal areas of the parietal cortex
visual assocaition cortex
auditory association areas
somatosensory areas
damage to the unimodal areas of the parietal cortex areas can lead to
sensory specific agnosias (inability to recognize faces perceive movement)
the inability to recognize faces, and preceive movement
Visual agnosias
location of the multimodal areas of the parietal cortex
Centered on intraparietal sulcus
roll of the multimodal areas of the parietal cortex
monitor relationships of body with outside world
damage to the right parietal lobe leads to
trouble with left half of body
deny something is wrong with left limb and can be convinced the left limb is someone else’s
ignore left half of body
ingorance of the left half of the body
contralateral neglect
left parietal lobe damage leads to
apraxius (lack of action)
symptoms of apraxias
unable to perform some actions, many diff types
how to test of apraxias
ask patient to imitate examiner who toucher finger to face and they can’t do it, but they can scratch an itch on their face
location of the prefrontal cortex
anterior to primary motor and supplemental motor cortices
the prefrontal cortex controls
activities of the other cortical areas, underlying executive functions
the prefrontal cortex is interconnected with what
dorsomedial nucleus of the thalamus
the 2 broad types of prefrontal cortex
dorsolateral (over lateral convexity)
Ventromedial (extends to orbitofrontal and anterior cingulate areas)
the dorsolateral prefrontal cortex interconnected with
parietal association areas
roll of the dorsaolateral prefrontal cortex
working memory (keep in mind), problems planning, solving problems, maintaining attention
damge to ventromedial prefrontal cortex leads to
makes people impulsive, can’t suppress inappropriate responses/emotions
