LECTURE 13: basal ganglia Flashcards
BG involved with not only motor control, but also what other 3 things
goal-directed actions, social behavior and emotions.
BG and cerebellum adjust motor tract activity via the ____ and have ___ direct contact with motor neurons
thalamus
no
BG predicts outcomes of actions and then chooses/executes the plan by ____ competing movements and facilitating others
inhibiting
the basal ganglia is deep brain nuclei that form what 5 things
caudate
putamen
globus pallidus , internus and externus
subthalamic nucleus
substantia nigra
caudate and putamen together form the ___
striatum
anterior junction of the putamen and caudate = ___ striatum
central
nucleus ___ = ventral striatum
accumbens
what does the putamen and globus pallidus form ?
lentiform nucleus
what nucleus is inferior to the thalamus and lateral to the hypothal
subthalamic nucleus
where is the substantia nigra located
midbrain
what is the only BG nucleus that is in the midbrain
substantia nigra
inputs to the BG come from the ___ thru the ____ pathways
cerebrum
corticostriatal
what is the NT that comes form the cerebrum thru the corticostriatal pathways
glutamate (excitatory)
inputs from the BG come from the cerebrum thru the corticostriatal pathways via what 3 things
striatum (caudate, putamen)
substantia nigra
subtahalamic nucleus
inputs from the BG come from the cerebrum thru the corticostriatal pathways via the striatum (caudate, putamen) ,substantia nigra pars compacta (SNc) and the subtahalamic nucleus, the inputs goes thur the SNc to striatum thru ___ pathways
nigrostriatal
what NT adjusts transmission in pathwyas between striatum and other BG nuclei
dopamine (
dopamine excitatory going to ___/___ pathway and ___ in indirect/No-Go motor pathway
direct/go
inhibitory
what are the 2 other NT for afferents into BG ?
ACH (excit)
serotonin (inhib)
outputs from BG goes from ___ ___ ___ to the thalamus to the ___ and ____ ___
globus pallidus internus
cortex
reticular formation (reticulospinal tract)
outs puts from the BG goes from the substantia nigra to the ___ colliculus and eye fields of ___ _____ and ___ tract
superior
premotor cortex
tectospinal
what NT comes from the outputs from the BG
GABA (inhbit)
what are the 2 motor loops of the basal ganglia circuitry
oculomotor loop and motor loop
what are the 3 loops of the non motor loops of the BG circuitry
goal directed behavior loop
social behavior loop
emotion loop
what loops of the BG circuitry are dorsal striatal pathways
oculomotor loop
motor loop
goal directed behvior loop
social behavior loop
which BG circuitry is part of the ventral striatal pathways
emotion loop
which BG circuitry loop is part of the limbic channel
emotion loo[
what channel is the goal directed behavior loop apart of
prefrontal channel
what cortex is the goal directed behavior loop apart of
lateral prefrontal cortex
the goal directed behavior loop in the BG comes from lateral prefrontal cortex to the ___ of the caudate whcih evaluated input for what 3 things ?
head
decision making, planning and picking actions most appropriate for the contect
after the goal directed behavior loop goes to the head of the caudate where does it go ?
globus pallidus internus
in the goal directed behavior loop what is responsible for linking the action chosen by the head of the caudate and performing selected movements
the thalamus
what are the deficits in the goal directed behavior loop (non motor loop)
decision making deficits (inattention , poor concentration , disorientation , poor short term mem, and distractibility
so what is the order of the goal directed behavior loop (non motor loop)
lateral prefrontal cortex > BG (head of caudate and GPI) > thalamus > back to the lateral prefrontal cortex
what loop is the 2nd part of the prefrontal channel
social behavior loop
which part of the cortex does the social behavior loop come from
ventral prefrontal cortex
in the social behavior loop the BG , the head of the caudate is aware of what 3 things
social cues regulates self-control, and determines relevant from irrelevant info
in the social behavior loop , what is the output in the BG after it goes to the head of the caudate
substantia nigra
what are the deficits for the social behavior loop
Impulsivity, indifference, easy to anger/become violent, risky behaviors
what is the order of the social behavior loop
ventral prefrontal cortex > BG ( head of caudate > substantia nigra reticularis ) > thalamus > back to the ventral prefrontal cortex
what part of the cortex is the emotion loop
medial prefrontal cortex
in the emotion loop , when it hits the BG the ___ striatum is responsible for __ and ___ and ___ as a link between emotional , cognitive , and motor systems
ventral
emotions
motivation
works
if someone has deficits for the emotional loop what would be imparied
reward seeking , addiction
in the emotion loop a ___ ___ stroke will causes depression and dulling of emotions
L BG
what is the order of the emotional loop
medial prefrontal cortex > BG (ventral striatum_ > thalamus > back to medial prefrontal cortex
what cortex does the oculomotor loop/channel come from
frontal and supplementary eye fields
for the oculomotor loop/channel (motor loop) , in the BG the ___ of the caudate decides about what 2 things
body
motions of the eyes and spatial attnetion
the oculomotor loop/channel is particularly the use of what 2 eye movements?
rapid eye movement ( saccades)
towards or away from an object ( reflexive prosaccades or antisaccades)
what are the deficits for oculomotor loop/channel
poor saccadic eye mvmt
what is the order of the oculomotor loop/channel
frontal and supplementary eye fields > BG ( body of caudate) > thalamus
what cortex does the motor loop/channel come from
motor and premotor cortex
what are the 2 structures in the BG that the motor loop/channel go thru
putamen and globus pallidus
does the motor loop/channel go thru the caudate ?
no
which loop/channel Regulates muscle contraction and force, multi-joint mvmts, and mvmt sequencing
motor loop/channel
what is the order of the motor loop/channel
motor and premotor cortex > putamen (in BG) > globus pallidus (in BG) > thalamus
disinhibition requires at least __ inhibitory neuron in series and __ target neuron
2
1
___ neurons inhibit their ___ neurons
inhibitory
target
when a 2nd inhibiotry neuron inhibits the 1st inhibiotry neuron what occurs ?
disinhibition
when disinhibition occurs it allows what
excitatory activity in target neurons
disinhibition is important for what
fine tuning of movement
is disinhibition a small or big part of BG function
big
for the motor loop what are the 3 internal pathways
stop
go
no-go
the 3 internal pathways of the motor loop all converge on ___ as an output nucleus
globus padallis internus
GPi inhibits ___ ___ whcih excites ___ motor areas and motor cortex excites motor neurons in the __ and ____
motor thalamus
cortical
SC and BS
are all 3 internal pathways of the motor loop needed for normal movement ?
yes
stop pathway is also termed what
hyperdirect pathways
in the stop pathway there is a strong ___ from the cortex to the ____ nucleus with excites the ___
excitation
subthalamic
GPi
in the stop pathway , what does the GPi inhibit
motor thalamus
in the stop pathway , immediately prior to movement initiation , this pathway strongly ___ current motor programs to ___ irrelevant movements
inhibits
stop
the go pathway is also termed what
the direct pathway
activation of the go pathway does what to motor
disinhibits
in the go pathway what inhibits GPi so it sends less inhibition (disinibition) to the motor thalamus
putamen
in the go pathway the motor thalamus transmits toe cortical motor areas to ___ specific ___ neurons
stimulate
corticospinal
no-go pathway is also termed ____ pathway
indirect
in the no go pathway ___ inhibits ___ which then inhibits less (disinbition) of the ___ nucleus
putamen
GPe
subthalamic
in the no go pathway the Putamen inhibits GPe which then inhibits less the
subthalamic nucleus and then the subthalamic nucleus excites ___
GPi
in the no go pathway the GPi then has _____ ____ of the motor thalamus and then ___ motor output to cortical motor areas
increased inhibition
less
what is the result of the no go pathway
inhibition of unwanted movements
what is also known as spiny projection neurons
medium spiny neurons
medium spiny neurons are special type of _____ inhibitory cells
GABAergic
what type of neurons compose of 95% of neurons within the striatum
medium spiny neurons
Putamens D1 and D2 receptors bind to ___-
dopamine
D1 receptors binding to dopamine ____ inhibitory neurons in ____
excites
GPi
___ receptors binding to dopamine inhibits neurons from putamen to ___ thus disinhibits that subthalamic nucleus and stimulates the __
D2
GPe
GPi
which putamen receptor (D1/D2) compose the direct pathway (go)
D1
which putamen receptor (D1/D2) compose the indirect pathway (No-go)
D2
motor loop requires ___ from the substantia nigra compacta
dopamine
____ , in normal quantities , regulates the tonic inhibition from GPi to motor thalamus , peduncleopontine nucleus and midbrain locomotor region depending on the motions desired
dopamine
does the BG have nay direct output to motor neurons?
no
motor loop regulates motor function thru how mnay pathways
3
the voluntary muscle activity of the motor control of the BG going thru the motor ____ to the motor ___ cell bodies in the ___
thalamus
tract
cortex
what 3 tracts does the voluntary muscle activity of the BG going thru
corticospinal
corticopontine
corticobrainstem
the postural and proximal limb muscle activity of the motor contorl by the BG going thru the _____ nucleus in the ____ to the ____ tracts to spinal ___ nerevs
pedunculopontine
midbrain
reticulopsinal
motor
walking pathway of the motor control by the BG going thru the ___ ___ region to the ___ tracts to stepping pattern generators
midbrain locomotor
reticulospinal
Too much Bg inhibtiton of motor thalamus , pedunculopontine nucleus , and midbrain locomotor region causes ___
hypokinesia
what is examples of hypokinetic disorders
parkinsons disease
atypical parkinsonisms
sceondary parkinsonism
what is the most common BG disorder
parkinsons
to little inhibition of the BG causes ___
hyperkinesia
what are 4 examples of hyperkinetic disorders
huntingtons disease /chorea
dystonia
tourette’s disorder
dyskinetic cerebral palsy
if someone has parkinsons diease the decreased dopamine from ___ is the primary changes leading to what
SN
leading to excessive activity of Gpi
is parkinsons disease a progressive neurodegenerative disease ?
yes
what are the 2 subtype symptoms of parkinsons disease ?
postural instability gait difficulty and tremor dominant subtype
what are the postural instability gait difficulty examples for someone with parkinsons
bradykinesia
poverty of movement (hypokineisa)
muscle rigidity
postural instability
autonomic dysfucntion
cognitive dysfunction
what disease is autosomal dominant hereditary disorder and causes cortical and striatum (esp putamen) progressive degeneration
huntingtons disease / chorea
in huntingtons disease there is 90% loss of subset of ___ inhibitory neurons in putamen and caudate so less input to ___
GABAergic
GPe (indirect/no-go pathway)
loss of excitatory output of subthalamc nucleus to GPi causing ballistic ____ movements of limbs called ___ ___ movements:
inovuluntary
chorei form
what are chorei form movements
involuntary , continuous movement of the body
huntingtons disease/chorea includes ___, ___ ,and ___ deterioration
motor
swallowing
cognitive
huntingtons disease causes thalamic neurons to fire randomly and inappropriately causing what
causing the motor cortex to execute motor programs with no control by patient
what is Genetic, typically nonprogressive, movement disorder characterized by involuntary sustained muscle contractions, causing abnormal posture, twisting and repetitive movements
dystonia
dystonia often ___ during activity and/or emotional stress
increases
T/F: dystonia does not vanish during sleep
F (it does)
are tremors associated with dystonia ?
no
examples of focal dystonias include what
writers or musicians cramp, cervical dystonia
generalized dystonias can be ___, including ___ and ___ , interfering with walking and other functions
progressive
limbs and trunk
