Brain Organization and Networking (Week 2) Flashcards
front of the brain
anterior
back of the brain
posterior
top of brain
dorsal
bottom of brain
ventral
side/outside of brain
lateral
middle/inside of brain
medial
4 lobes of the brain
frontal, parietal, occipital, temporal
frontal lobe function
decision making, planning, motor control, high level thinking
parietal lobe function
touch, spatial transformation of spaces, spatial recognition)
what separates the frontal and parietal lobe
central sulcus
temporal lobe function
hearing, higher level vision
occipital lobe function
vision
brainstem components
midbrain, pons and medulla
cerebellum
“little brain”
*has as many cells as in the cerebral cortex
which sensory pathway does NOT go through the thalamus
sense of smell
sensory pathway: eye
light -> retina -> thalamus (LGN) -> primary visual cortex (V1) in posterior occipital lobe
sensory pathway: ear
inner ear -> processing in brainstem -> MGN -> primary auditory cortex (A1)
sensory pathway: skin
touch receptors in skin -> processing in brain stem -> thalamus -> primary somatosensory cortex (S1)
which sensory pathway goes straight to thalamus (no brainstem processing step)
eye
first order thalamic areas
thalamic areas that receives major input from sensory periphery
brodmann’s areas
regions of the cerebral cortex that are defined by their cellular structure and organization
brodmann’s area 17
primary visual area
hierarchical organization of cerebral cortex
primary sensory areas, secondary sensory areas, higher-order areas
what kind of info processed in lower level areas in cerebral cortex
simple sensory aspects (ex. vertical vs horizontal line orientation)
what kind of info processed in higher level areas in cerebral cortex
abstract/complex representations
feedforward pathways
carry info about sensory environment from posterior -> anterior
feedback pathways
carry complex info (behavior, goals, predictions, etc) from anterior to posterior
*modulate posterior area activities and select for more behaviorally relevant information
where in the cerebral cortex is more complex information
front of the brain (anterior)
what are the 2 “parts” of the thalamus
first-order thalamus- info from sensory organs
higher-order thalamus- information from cerebral cortex
how is information passed from the primary sensory cortex to secondary and higher order sensory cortices
go through the higher order thalmus each time
what are the 2 brainwide pathways in your visual system
dorsal pathway/ how pathway and ventral pathway/what pathway
dorsal pathway
the how pathway on the top of the brain; how to use an object/ where it is
ventral pathway
the what pathway on the bottom of the brain; identify what an object is
how many layers in the cerebral cortex
6
*different areas of the brain show different layering
cytoarchitectonics
arrangement of neurons in the brain
how thick is the cerebral cortex
2-3mm
what is the thickest/densest layer in the primary visual cortex?
layer 4; receives signals from sensory systems
what is layer 4 of the cerebral cortex called
granular layer (very dense)
why does primary motor cortex have small layer 4
does not receive many signals from sensory systems
how many brodmann’s areas are there
52
cytoarchitectonic maps
maps that depict neurons in the brain
ex. brodmann
what is the vertical organization of neurons in the cortex
repeating units of cortical columns containing cortical minicolumns acorss cortex
cortical column size
0.4-0.5mm in diameter
cortical minicolumn size
30-50 microns in diameter
what types of cells are in the cerebral cortex
pyramidal cells, stellate and interneurons
pyramidal cells
-make up 70% of cells in cerebral cortex
-excitatory cells; depolarize postsynaptic cells
-can excite cells next to it or across the brain
stellate cells
excitatory cells in cortex but not excitatory everyone else in brain
interneuron cells
inhibitory cells that hyperpolarize postsynaptic cells
canonical microcircuit of the cerebral cortex: what layer receives feedforward input from thalamus and other cortical areas
layer 4
canonical microcircuit of the cerebral cortex: what layer(s) send feedforward output to other cortical areas
layers 2/3
canonical microcircuit of the cerebral cortex: what layer sends feedforward output to subcortical areas (ex. thalamus, basal ganglia)
layer 5
canonical microcircuit of the cerebral cortex: what layer sends feedback output to thalamus or other cortical areas
layer 6
canonical microcircuit of the cerebral cortex: what layer receives feedback input from thalamus and other cortical areas
layer 1
large difference between rodent brains and primate brains
no granular frontal cortex (no layer 4)
what is the basal ganglia
collection of cell bodies in deep brain; play crucial roles in motor control, cognitive function, and emotional regulation
what are the structures in the basal ganglia
striatum (caudate nucleus and putamen), internal and external globus pallidus, subthalamic nucleus
what is the loop that describes how information is transferred to and from cerebral cortex
cortico-striatal-thalmic loop
cortico-striatal-thalmic loop mechanism
cerebral cortex -> striatum -> pallidum/nigra -> thalamus —> back to cortex
what are the 2 places in the cerebral cortex that do NOT project their processing to the striatum (in the basal ganglia)
primary visual and primary auditory cortices
what does the basal ganglia contribue to
action selection and reinforcement learning
basal ganglia direct pathway
cortex -> striatum -> gp internal segment which inhibiting the inhibitor on the higher order thalamus -> sends info to cortex
basal ganglia hyperdirect pathway
cortex to subthalamic nucleus; inhibits thalamus quickly
basal ganglia indirect pathway
cortex -> striatum ->internal GP -> subthalamic nucleus -> external GP -> inhibits thalamus
what does increased strial activity do in the direct pathway
disinhibit the thalamus; inhibits the GP internal segment which removes inhabition on the thalmus
cortico-cerabeller system
motor cortex and prefrontal cortex send messages to cerebellum; muscle memory
cortico-cerabeller system mechanism
cortex sends info to pontine nuclei in the pons (brainstem) -> cerebellum -> thalamus -> back to cortex
effrence copies
copy of motor/ cognitive command sent to cerebellum from cortex; predict sensory consequences so one can adapt quickly
cortico-hippocampal system
cortex can communicate with hippocampus indirectly though thalamus and parahippocampal areas BUT hippocampus can directly send info to cortex
hippocampus function
episodic memory (autobiographical) and spatial navigation
parahippocampal areas
parahippocampal cortex, perirhinal cortex, entorhinal cortex
where is the hippocampus located
medial temporal lobe
regular network pros and cons
pros: can form local clusters -> specialization
cons: long time to transfer info far away
random network pros and cons
pros:quick long range connections
cons: no local connection/specialization
small world network
local and long ranged connections!
module
subset of nodes with high within model connectivity and low intermodal connectivity
high degree node
node with lots of connections to other nodes (hub)
low degree node
node that is more isolated/ not as many connections
path length
minimum number if edges to go from 1 node to another
clustering coefcient
number of connections that exist between nearest neighbors of a node; proportion of maximum possible connections
rich node
node with large number of connections; hub
rich club
rich nodes that are well connected with eachother
rich club organization
greater likelihood of high degree nodes forming rich clubs than low degree nodes
main brain hubs
precuneus, cingulate cortex, superior frontal cortex, insular cortex, lateral parietal cortex, thalamus
ways to map anatomical connections in brain
-tracer studies (chemical travels down axon and you can see which neurons are connected)
-function MRI: infer direction of white matter (axon) path based on water diffusion
how to interpret connectivity from a fMRI
water diffuses more easily along connections between brain areas; connect voxels based on prefered discussion directions
