Motor Control - Basal Ganglia Flashcards
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
the basal ganglia is actually
several nuclei in a loosely arranged group.
not all nuclei in the basal ganglia participate in motor control, but
most do
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
striatium =
putamen and caudate nucleus
Nigrostriatal dopaminergic system
from
to
effects
SNPC
nuclei of striatum
D1 receptors +, D2 receptors -
The intrastriatal cholinergic system
between
effects
between the nuclei of the striatum
excitatiory
The striatonigral Gaba-ergig pathway
from
aka
leads to
stratum to the SNPR and Gpi
“the direct pathway”
initiation of movement
information leaves the basal ganglia via the
SNPR and GPi
the SNPR and the GPi project to the
thalamus, releasing GABA within the thalamus
- to cortex via thalamus
- to brainstem and spinal cord
Nuclei of the basal ganglia
substantia nigra -pars compacta -pars reticulata striatum -caudate -putamen Globus pallidus -external segment -internal segment subthalamic nucleus
neurotransmitters of the Basal ganglia (3)
dopamine
cholinergic
gabanergic
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
CHolinergic system in the basal ganglia
cell bodies
axons
function
neurons of striatum
synaps on other neurons in striatum
excitation
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
Inputs of the basal ganglia
substantia nigra pars compacta receives input and relays them to the striatum
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
Motor control - basal ganglia
what they do
control begining and to a lesser extent the end of movement
how do the basal ganglia work
by inhibition and withdrawal of that inhibition (to start movement)
excess of gabba
Basal ganglia work from ___via ____
cortex via corticostriate track
What receives the input for the basal ganglia
STRIATUM
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
- direct pathway beomes difficult to activate
- 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
