Basal Ganglia Flashcards
Basal Ganglia function
goal oriented mvmnt, automaticity, efficient and selective production of well learned motor plans
Basal ganglia has more of a connection with what motor area
SMA
Cerebellum has more of a connection with what motor area
PMA
Basal ganglia plays an important and major role in what (most cutting edge role)
Selection! focusing neural activity and supressing alternative mvmnt patterns based on some sort of reward or motivation of the person
Basal ganglia is a group of
nuclei
GREY MATTER!
cell bodies of neurons that live together
What makes up the stiratum
caudate and putamen
What are the input components of the BG
Striatum! Caudate and putamen
Caudate receives info from where
prefrontal
Caudate receives what type of info
cognitive
Putamen receives info from where
primary motor
Putamen receives what type of info
motor
5 nuclei of the BG
Caudate Putamen GP (GPi and GPe) Subthalamic nucleus Substantia nigra
Globus pallidus does what
integration of infomation
Globus pallidus is made up of what
Gp internus and externus
Subthalamic nucleus (STN) is located where
below the thalamus
Substantia nigra is located where
midbrain
what is in the internal capsule
white matter - axons from the cortex - major highway of ascending and descending pathways - lateral cortical spinal tract
It houses the largest descending pathways
BG components include
input, modulator, output, facilitator
BG input
striatum (caudate and putamen)
BG modulator
substantia nigra compacta
SN compacta - known for what
Parkinsons - SN has dopamine producing cells
Internal circuitry of BG relies on dopamine so when not producing dopamine correctly - get mvmnt disorder
BG output
GP internus
Substantia nigra reticulata
GP internus acts directly on the
thalamus
BG facilitator
subthalamic nucleus
BG gets input from wide variety of areas and integrates this and then goes to the thalamus and targets the same cortical areas - T or F
TRUE!
Skeletal motor loop/body mvmnt loop/motor circuit - where does it get input from
primary motor, premotor, supplementary motor
Cognitive loop/Corticothalamic loops/oculomotor and prefrontal get input from where
Prefrontal mainly
Motor loop - circuit
MI, premotor, SMA - putamen - GP - thalamus
Cognitive loop - circuit
Prefrontal- caudate - GP - thalamus
Limbic loop - gets input from where
Amygdala
Orbital frontal
Ant cingulate
Limbic loop - circuit
Amygdala/orbital frontal/ant cingulate - striatum - GP - Thalamus
Is the BG only getting input from motor areas
NO - all of these are linking cognition with mvmnt in some way
BG represents ____ function
distributed!
BG motor circuit - within the circuit there are ___ and ___ pathways
Direct and Indirect!
Direct pathway of the motor circuit - function
Drives the cortex gas!
Direct pathway of the motor circuit - what does it do - how does it work
Reduces inhibitory output to thalamus (inhibit gpi)
Direct pathway of the motor circuit - What is the end result from it
thalamocortical neurons are activated
What do you need for the motor pathways to work
SN to supply the dopamine!
Output from putamen is what
inhibitory
Output from gpi is what
inhibitory
Putamen is sending inhibition to the gpi which means what
it is inhibiting the inhibitor so the net is excitatory
What is the net effect of the direct motor circuit pathway
Excitatory!
The direct motor circuit focuses and facilitates what
Wanted/Intended movement
What is the hyperdirect pathway
Turns on STN (subthalamic nucleus) which turns on gpi which makes gpi send out inhibition to the thalamus
Function of hyperdirect pathway
It is in constant use to tonically inhibit these neurons so that we arent moving around so much - and then the direct and indirect pathways decide what input will go through and what will not
BG allows you to ___ neural activity
focus
BG - indirect motor pathway - function
reduces drive of the cortex
BRAKE
Indirect pathway of the motor circuit - what does it do - how does it work
Inc inhibitory output to thalamus
Facilitates gpi vis gpe and STN
Indirect pathway of the motor circuit - What is the end result from it
Inhibits the thalamocortical neurons
Less info going back up to cortex - so whatever the plan was is not being facilitated
Net effect of the indirect motor pathway
Inhibitory
Parkinsons disease - what is going on at striatum
Reduced facilitation
Parkinsons - the direct pathway
is not facilitated
Parkinsons - the indirect pathway
is not inhibited
Losing the direct path (parkinsons) leads to what
gpi is not getting checked so is in a constant state of inhibition
continuously working off hyperdirect which is inhibitory
More specifically what do you lose with parkinsosn
the gas pedal to the movements planned by the SMA
internally generated movements
Why do auditory and visual cues work for patients with parkinsons
External cue so it is using a different pathway - not internally generated anymore! External cues will drive the premotor system which is still working! cbm and PMA are fine!
BG - Huntington’s is what
reduced inhibitory gpi output
BG - Huntingtons - what happens to direct and indirect pathways
Indirect pathway is lost
Gpe is inhibiting gpi
Lose gpi inhibition of the thalamus
BG - huntingtons- end result
movement is facilitated
You have involuntary, unpurposeful movement
BG - subserves what
goal directed bx related to cognition, movement, mood
BG - circuits link what
cortex and BG
BG - simultaneously activated indirect and direct pathways fxn to
produce focused selection of an intended response
BG - direct pathway - ____ ____ cortical pattern generating neurons
selectively activates
BG - indirect pathway - ___ ___ of pattern generating cortical neurons
general inhibition
