Cerebral cortex- cells to function Flashcards
do humans have unipolar cells
no
where does action potential get triggered
axon hillock
classify neurons into number of processes they have
unipolar
bipolar
multipolar
pseudo-unipolar cells (start as bipolar then fuse), peripheral and central process- looks like uni polar
where do you find bipolar nerve cells
special sense organs- SENSORY
ears, eyes, nose
what is the commonest type of neuron in cns
multipolar neuron
what does it mean if the neurons have short axon vs long axon
short axon- local processing
long axon- sending info to another region/ long way
what type of multipolar cell has a long axon
pyramidal cells
send info from cerrebral cortex
what type of neuron has short axons
interneuron
for local processing
what does oligodendrocyte mean
few process cell
one cell connects to multiple axons
multiple internodes for different axons.
what happens to the unmyelinated axons
PNS- schwann cells envelope unmyelinated axons- containing 1 or more axons
CNS- no embedding or association with glial cells
what are examples of unmyelinated axons
sensory fibres carrying pain, temperature, itch
what kind of conduction do unmyelinated axons have
continuous conduction of AP due to passive current flow.
what is a demylinating type disorder
multiple sclerosis
what are the glial cells of the cns
oligodendrocytes
astrocytes
microglia
ependyma
what are the glial cells of PNS
schwann cells
satellite cells
do astrocytes form the blood brain barrier
no
describe the difference found in white vs grey matter astrocytes
white matter- fibrous
grey matter- protoplasmic (more blobby lol)
describe astrocytes
star like
control water distribution
potassium buffering (K+ in AP regulated via astrocytes)
Reactive oxygen species scavenging (bad things that cause stress and cell death)
define architecture of brain (strong rope like filaments)
regulate migration/ pruning/ synaptogenesis
maintain BBB
build scar tissue
what is the bbb composed of
endothelial cells and their tight junctions
astrocytes and bbb
maintain cells that make BBB
integrity highly dependent on astrocyte end feet
describe microglial cells
phagocytosis and antigen presentation (immune response)
synaptic pruning
(blobs lol)
describe ependymal cells
they line the ventricles and tubular systems
they are ciliated cuboidal epithelial cells
secrete CSF and reabsorb CSF
how is CSF produced
produced in specialised ependyma on choroid plexus
how many layers does the cerebral cortex have
6
what are the limited areas of lamination
3 and 4 layers (older evolutionary)
what are layer 2 and 4 used for
what is between these layers
layer 2 and 4 are involved in input
within the layers there are stellate interneurons
granular layers contain the interneurons
have internal and external granular layers
what do layers 3 and 5 do
sending info out OUTPUT
contain pyramidal layers (external and internal)
external- are local communication
internal- sending info far!
are there more pyramidal cells in the motor cortex
yes because sending info out!
vice versa for sensory cortex
what is the strip of high density found in layer 4
stria of Gennari
huge input from outside to INTERNAL GRANULAR LAYER- visible with naked eye
Internal means FAR
runs parallel to cerebral cortex
what are the Brodmann areas
created a map that shows subtle differences in structure- was done via histology
turns out it relates CLOSELY to function
what are some way to map the brain
disease, damage effects
fMRI
PET
electrical stimulation (during surgery)
what does fMRI stand for
functional MRI
What are association cortexes
give an example
do much more complicated things than the primary areas
bigger
next door
for example primary visual cortex within occipital lobe–> also had motion, object recognition, depth, binocular, patterns near primary motor cortex
association cortex for vision= all of occipital lobe plus more (sensory cortex!!)
what is the dorsal stream
The dorsal stream, or where pathway, describes a hierarchy of areas that support visually-guided behaviors and localizing objects in space.
what is prosopagnosia
inability to recognise faces
what causes prosopagnosia
damage to fusiform gyrus area 37
what happens when there is damage to the dorsal stream area
optic ataxia
what happens when there is damage to the ventral stream area
prosopagnosia
is vision processed outside the occipital lobe
yes
use sensory cortex as well
it flows therefore–> dorsal stream.
where are faces recognised
temporal lobe
what does association area do
integrate, processing of cognate primary cortex info
two types- unimodal (processing one type on input) and polymodal (vision and sensory mixing)
becomes mixed further away (touching, vision, reacting, motor) therefore integrating eg. a reaching movement
what does dorsal stream do
vision for ACTION /movement
integrate motion vs object locations
coordinate visual guided action for skilled movements
guides visual attention
what does ventral stream do
vision perception RECOGNITION
recognition infero-temporal cortex
distinguishes spatial patterns, objects and faces
stores visual memory
recognises significance of objects and faces
why are some areas enlarged in homunculus
lots of sensory and motor and therefore fine movement
hand and face
lips tongue
what are the motor association cortex regions
- supplementary motor area in longitudinal fissure PLANNING COMPLEX TASKS
- premotor cortex PREPARING FOR ACTION (posture and gait, spatial info)
- posterior parietal cortex INTEGRATING SENSORY TO MAKE MOTOR COMMANDS
what is the relation between primary somatosensory cortex and central sulcus
further towards asxociation cortex- more complex
what are the somatosensory cortexes
and what do they do
inferior parietal lobule
superior parietal lobule
awareness/perception in space, rearrangement of memories, organising grasping movements, number processing, MIRROR NEURONS FOUND HERE
what happens if there is damage ti the inferior parietal lobule
contralateral neglect
astereognosis
what happens if there is damage to the superior parietal lobule
optic ataxia- problems with visuomotor integration
what are the features of frontal lobe damage
personality changes
deficits in planning
perseveration
primitive reflexes
abulia
what is the function of prefrontal lobes
contributes to attention
morality
planning
working memory
conscious decision making
social behaviour regulation
what is expressive aphasia
cant express words, but can understand
how do you get expressive aphasia
damage to brocas area
what is wernicke area used for
comprehension speech
not execution
where are brocas and wernickes area near
near primary auditory area
what is receptive aphasia
unable to understand/ generate meaningful language
what is conduction aphasia and what causes it
difficulty repeating words
damage of arcuate fasiculus (association bundle that connects Wernicks and Brocas areas)- two areas cant communicate
what percent of people have a dominant left hemisphere
96%
other 4 normally has damage
hemisphers are specialised how?
left mostly dominant
left- language and calculation
right- drawing, music, spatial perception
found out during corpus callosum cutting
why cut corpus callosum in bad epilepsy
stop electrical activity of brain spreading
what is the feels the key experiement
cant transfer info to other side
recognition happens but word formation cant happen
what does dti do
trace white matter and therfore communication pathways.
what is commissural , association and projection communication
- cortex to cortex over midline
- cortex to cortex “stay” on same side
- communicate with other structures inside and outside the brain
two ways to test specialisation of hemispheres?
feel the keys experiment
touch the finger test
