Motor Control - Basal Ganglia Flashcards by Katie Smeltzer

without the basal ganglia, you’ll either end up

a) being unable to initiate the motion that will grab an objet
b) getting ‘stuck’ at the start of the motion, only able to repeat the action

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the basal ganglia is actually

several nuclei in a loosely arranged group.

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not all nuclei in the basal ganglia participate in motor control, but

most do

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Nuclei of the basal ganglia

subthalamic nucleus
substantia nigra pars compacta
substantia nigra pars reticulata
putamen and caudate= striatum
globus pallidus internal (medial) segment
globus pallid us external (lateral) segment

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striatium =

putamen and caudate nucleus

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Nigrostriatal dopaminergic system
from
to
effects

SNPC
nuclei of striatum
D1 receptors +, D2 receptors -

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The intrastriatal cholinergic system
between
effects

between the nuclei of the striatum

excitatiory

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The striatonigral Gaba-ergig pathway
from
aka
leads to

stratum to the SNPR and Gpi
“the direct pathway”
initiation of movement

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information leaves the basal ganglia via the

SNPR and GPi

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the SNPR and the GPi project to the

thalamus, releasing GABA within the thalamus

to cortex via thalamus
to brainstem and spinal cord

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Nuclei of the basal ganglia

substantia nigra
-pars compacta
-pars reticulata
striatum
-caudate
-putamen
Globus pallidus
-external segment
-internal segment
subthalamic nucleus

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neurotransmitters of the Basal ganglia (3)

dopamine
cholinergic
gabanergic

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Dopamine system in basal ganglia
cell bodies
axons
receptors

substantia nigra pars compacta
travel to the striatum
D1 and D2 receptors on different neurons in striatum

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CHolinergic system in the basal ganglia
cell bodies
axons
function

neurons of striatum
synaps on other neurons in striatum
excitation

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GABAergic system in the basal ganglia
cell bodies
axons
function

striatum
travel to Globus pallid us internal segment and the substantial nigra pars reticulate
inhibition

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Inputs of the basal ganglia

substantia nigra pars compacta receives input and relays them to the striatum

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outputs of the basal ganglia

GPi and SNPR send axons to the thalamus - when activated they release GABA at synapses in the thalamus=inhibition of thalamus

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Motor control - basal ganglia

what they do

control begining and to a lesser extent the end of movement

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how do the basal ganglia work

by inhibition and withdrawal of that inhibition (to start movement)
excess of gabba

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Basal ganglia work from ___via ____

cortex via corticostriate track

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What receives the input for the basal ganglia

STRIATUM

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Nigrostriatal path
from
tonic condition
NT

from SNPC
tonically active
dopaminergic

Pars compact of substantial niagra sends _______ to act on the ____

dopamine Striatum

the ____ receives most?all of the input related to motor control

putamen

the effect of dopamine released in the striatum that there are

two distict pathways within the basal ganglia that control motion

Direct pathway in the basal ganglia that controls motion

D1 excited by dopamine allows motion

Indirect pathway in the basal ganglia that controls motion

D2 inhibited by dopamine, excited by EAA/Ach inhibits motion

The direct pathway - from striatum to

SNPR and GPI SNPC -->dopamine to Striatum=+ Striatal cell release GABA--> SNPR and GPI (-) SNPR and GPi are inhibited and therefore release less GABA in the thalamus (thalamus is less inhibited)

by inhibiting the SNPR and GPi, LESS GABBA is released in the ______. The _____ is then free to ______ allowing

thalamus. | thalamus is then free to excite the cortex, allowing the initiation of movement

indirect pathway - from SNPCis _____ due to

inhibitory | striatal neurons that are part of the indirect pathway due to D2 reeptors

To activate the indirect pathway, we must use input from

the cortex and the intrastriatal pathway

Striatal neurons synapse on the _____ releasing _____

GPe, GABA

by activating the stratal neurons we release _______ in the GPe. Result?

more GABA | (-) Gpe

the neurons of the GPe synapse in the

subthalamic nucleus

when the Gpe neurons are less active, there is ____ inhibition of the sub thalamic nucleus

less

nt release by the Gpe

GABA

neurons from the sub thalamic nucleus synapse in the_____. in the indirect pathway, since the sub thalamic neurons are less inhibited (more active) MORE _____ are released in the SNPR

snpr. | EAA

What ne does the sub thalamic nucleus release

EAA

with activation of the indirect pathway, there is ______ of the SNPR and GPI, meaning ______ is released in the talamus. The thalamus is then ________, _______ing excitation of the cortex, resulting in ______

more excitation more gaba inhibited decreasing suppressing the initiation of movement

Direct pathway - summary

``` to activate - SNPC sends dopamine to striatum dopamine binds D1 receptors striatal neurons are excited axons releas GABA in GPi and SNPR when active - allows motion ```

Indirect pathway - smmary

to activate- cortical inputs release EAA striatal neurons of indirect path are excited axons synapse in Gpe, release GABA GPE axons travel to the sub thalamic nucleus (GABA) axons from sub thalamic nucleus traeelt to Gpi and SNPR (EAA) when active - inhibit motion

parkinsons, the ____ input is abolished

SNPC

parkinsons effects of SNPC input being abolished

1. direct pathway beomes difficult to activate 2. inidrec pathway becomes overactive, due to loo of inhibition we see an inability to initiate motion

Voluntary motion: association cortex - two major areas of function

planning of complex motor actions | carrying out of thought process

Higher functions of the brain are in what cortex

prefronal cortex

planning com complex motor actions -

prefrontal cortex interacts with parieto - temporal - occipital association areas and all levels of motor cortex

planning of a complex motor action requires what areas of the cortex and brain

frontal association area supplementary motor cortex premotor cortex cerebrocerebellum

interactions between the fontal, premotor, supplementary motor, and basal ganglia determine

IF the motion will occur

once the motion is planned, sequenced, and "approved"

the appropriate columns in the primary cortex are activated

when the columns in the primary motor cortex are activated, APS travel down the _________ and activate the

pyramidal cells | the alphamotorneurons tha innervate the muscles needed to complete the motion

in planned motions, the muscle spindle could be a problem as it will oppose every motion we make unless we do something about it. The brain :solves" this problem by

using the gamma motor neurons to trick the muscle spindle into believing that the muscle is not changing lengthe

To make motion occur, if the brain activates the alpha motoneuron, and also activates

the gama motorneuron fro spindles in the contracting (agonist muscle)

To make motion occur, if the brain inhibits the alpha motor neuron, it also inhibits the

gamma motorneruon fro spindles in the stretchin (antagonist) muscle

ONce the motion has started, the _____ is used to make sure the motion is correct

spinocerebellum