CC Flashcards
How many layers does the neocortex have?
6
95% of cortex
How many layers does the paleocortex have?
3
uncus, olfaction
How many layers does the archicortex have?
3
most of hippocampus
How many apical dendrites does a pyramidal cell have?
one per cell, extends to top of cortex
How many basal dendrites does a pyramidal cell have?
many per cell, extend horizontally in cell layer
What are the most prevalent type of cells in the cortex? are they excitatory or inhibitory?
pyramidal cells are principle projection neurons
excitatory
What are dendritic spines?
on pyramidal cells, preferential site of excitatory synapses, highly regulated
may be in solved in autism, fragile X syndrome
Are non-pyramidal cells excitatory or inhibitory?
mostly inhibitory
What are the different types of non pyramidal cells?
spiny stellate cells
smooth stellate cells
bipolar cells
Describe spiny stellate cells
have spiny dendrites
general excitatory synapses w/ pyramidal cells
receive afferent info from thalamus and other areas
Describe smooth stellate cells
non spiny dendrites
inhibitory (GABA synapse w/ pyramidal)
receive recurrent collaterals from pyramidal cells (sense weakly active pyramidal cell columns and shut them down)
Describe bipolar cells
located mainly in outer layer and contain peptides that are co-released w GABA
What are the six cell layers of the cortex, from outer most to innermost?
I: Molecular II: Outer Granular III: Outer pyramidal IV: Inner granular V: inner pyramidal VI: fusiform
What is in the molecular layer?
mostly acellular
has ends of pyramidal dendrites
Whats in the outer granular layer?
small pyramidal and stellate cells
Whats in the outer pyramidal layer?
medium sized pyramidal and stellate cells
What layer of the cortex receives thalamocortical axons (relay nuclei)?
inner granular layer
What layer of the cortex makes up the cortical spinal tract?
inner pyramidal layer
Whats in the fusiform layer?
modified pyramidal cells projecting to thalamus
What layer is the line of gennari found in?
inner granular layer
What are the afferents to the cortex? (5)
- association fibers: from small and medial sized pyramidal cells in other parts of IPSI cortex
- commissural fibers: from medium sized pyramidal cells through corpus callosum or anterior commissure (R talks to L cortex)
- Thalamocortical fibers: from relay or association nuclei
- non-specific thalamocortical fibers: from intralaminar nuclei
- cholinergic and aminergic: from basal forebrain, hypothalamus, brainstem (MB raphe, locus ceruleus)
What are the efferents from the cortex?
- short association (to neighboring areas)
- long association (from lobe to lobe)
- commisural fibers
- primary sensory/motor to basal ganglia
- from all areas of cortex to thalamus
- corticopontine
- corticospinal
- corticobulbar
T/F: all efferents are pyramidal cell axons and all are excitatory
tru
What would you expect to find in an agranular part of the cortex, and where would you find it?
- lots of pyramidal cells, long axons
- found in motor areas of cortex
What would you expect to find in a granular part of the cortex, and where would you find it?
- fewer pyramidal cells because sensory areas project to nearby areas of cortex
- found in sensory areas
Does the neocortex show regional specification?
Yes (brodmann’s areas: based on cell density)
but it is highly variable, structure not that tightly correlated with function
What are the main types of cortical regions? (4)
- Primary motor areas: give rise to cortical spinal tract
- primary sensory areas: receive info from thalamic sensory relay nuclei
- association areas: higher order sensory
- limbic areas: memory and stuff
How are sensory areas of the cortex arranged?
somatotopically
map is distorted so that highly sensitive areas have disproportionately large areas (think the giant lips thing)
What is the general function of the primary somatosensory cortex and where is it located?
initial processing of tactile and proprioceptive information
parietal lobe
What part of the parietal lobe is involved in language comprehension?
left inferior parietal lobule
Where is the primary visual cortex located?
occipital lobe in banks of calcimine sulcus
What happens if you have a bilateral injury to the inferior occipital lobe?
color blindness
What happens if you have a bilateral injury to the occipital-temporal junction?
motion blindness
Why is the primary visual cortex called the striate cortex?
very defined line of gennari (stripe of white matter)
How is the LGN organized?
into 6 different layers, each layer gets info from one eye.
What do the parvocellular layers of the LGN perceive?
color and form
What perceives movement and contrast in the LGN?
magocellular layers
Where does the LGN project?
primary visual cortex
shit is upside down and backwards thing, like inferior field is superior etc etc
What is the role of the primary visual cortex in vision?
breaks info down into parts: color, orientation, depth, motion etc
simultaneous, parallel processing!
recognizes duck as being duck
T/F: cortex has a columnar organization
yes, columns of neurons have a very specific modality
especially noticeable in visual cortex areas
Are columns associated with the fovea large or small?
small–more “pixels”
What goes into the ventral striate cortex?
parvocellular layers (color and form)
What goes into the dorsal striate cortex?
magnocellular layers (location, movement)
What are the temporal lobe functions?
primary auditory cortex
auditory association cortex
language comprehension (wernicke’s)
higher order visual processing
Where is the gustatory cortex?
frontal lober (operculum and insula)
Where is the vestibular cortex?
superior temporal gyrus and posterior insula
T/F: the olfactory complex is part of the neocortex
false, it is part of the paleocortex
Where is the olfactory complex locate?
around amygdala, parahippocampal region
What are the main functions of the frontal lobe?
motor areas of brain
broca’s area: production of speech
prefrontal cortex: executive functions, personality etc
What does a unimodal association area do?
elaborates on what the neighboring primary area generates
What does a multimodal association area do?
high level intellectual functions
What is a ‘dominant hemisphere’?
wherever language areas are located
What side is dominant in most people
left
even for left handed ppl
Which lateral sulcus extends further back and why?
left, because the planum temporale is larger
What is the planum temporale?
part of superior temporal gyrus, posterior to auditory cortex
Where are language areas generally located?
near the left lateral sulcus
think about motor homunculus thing: mouth areas are near lateral sulcus…need your mouth to talk
What lobe is brocas area in?
frontal
What lobe is wernicke’s area in?
temporal
nonfluent aphasia: where
broca’s
Can someone with broca’s aphasia understand language?
yes, but they cannot produce speech
fluent aphasia: where
wernicke’s
Can someone with wernicke’s aphasia understand language?
no, they just spew a bunch of nonsensical words endlessly
How do broca and wernicke’s areas communicate?
white matter tract called arcuate fasciculus
What role does the right hemisphere play in language?
produces emotional content (rhythm, tone etc), called prosody
What area produces prosody?
right inferior frontal gyrus (think about broca)
What area understand prosody?
right posterior temporoparietal region (think about wernicke)
What happens if you damage your right parietal lobe?
you have trouble with left side of body–can even reject its existence
What happens if you damage your left parietal lobe?
can’t plan movements accurately
called apraxias
ask patient to touch nose–cant do it
What part of the cortex is interconnected with the dorsomedial nucleus of thalamus?
prefrontal cortex
What part of the prefrontal cortex is involved in working memory, solving problems and maintaining attention?
dorsolateral
What part of the prefrontal cortex is involved in making people impulsive and unable to suppress emotions?
ventromedial
What do the corpus callosum and anterior commissures connect:
CC: opposite sides of cortex
anterior commissure: inferior temporal lobes, olfactory nuclei
When would ‘alexia without agraphia’ occur?
if the corpus callosum is damaged, you may be able to write but not read because your language areas on the left are isolated from all visual input
