26-Motor7-BasalGanglia Flashcards
Main components of basal ganglia (x4)
- neostriatum (caudate and putamen)
- globus pallidus
- subthalamic nucleus
- substantia nigra
The ___ receives major inputs to basal ganglia
neostriatum
caudate and putamen grouped together because
they are cytoarchitecturally similar nuclei
neostriatum:
primary output neurons
spiny neurons
neostriatum:
two subtypes of spiny neurons
- GABA/substance P (SP)
- Gaba/enkaphilin (ENK)
SP
substance P
ENK
enkephalin
neostriatum:
secondary neurons
aspiny neurons and interneurons
corticostriate pathway originates from ___
many cortical areas, especially premotor and primary motor cortex
corticostriate pathway terminates on ___ neurons in ___
spiny (both subtypes), neostriatum
corticostriate neurons are [excitatory/inhibitory]
excitatory (glutamate)
corticostriate information reflects [specific/nonspecific] cortical activity
specific
thalamostriate originates from ___ thalamic nuclei
midline
thalamostriate neurons are [excitate/inhibitory]
excitatory (glutamate)
thalamostriate information reflects [specific/nonspecific] activity
nonspecific, from reticular formation (arousal and attention)
striatum outputs to ___ and ___
GPi and GPe
direct pathway involves GABA/___ neurons to ___
SP, GP_i
indirect pathway involves GABA/___ neurons to ___
ENK, GP_e
globus pallidus (internal) is major [input/processing/output] system
output
GP_i projects to ___
VA/VL of thalamus
GP_i is mainly [excitatory/inhibitory]
inhibitory (GABA)
GP_e projects to ___
subthalamic nuclei (STh)
STh
subthalamic nuclei
GP_e in mainly [excitatory/inhibitory]
inhibitory (GABA)
true
Two parts of substantia nigra
- pars compacta
- pars reticulata
striatonigral projection originates from ___
spiny neurons (primarily GABA/SP)
striatonigral projection is primarily [excitatory/inhibitory]
inhibitory
SNr is to ___ mvt as GP_i is to ___ mvt
eye, limb
SNr projects to (x2)
- VA/VL of thalamus
- brainstem
SNc projects to (x1)
striatum, spiny neurons
SNc uses ___ as neurotransmitter
dopamine
SNc ___ GABA/ENK neurons and ___ GABA/SP neurons ([excites/inhibits])
inhibits, excites
Input to STh originates in ___
lateral segment of globus pallidus (GP_e)
Input to STh from GP_e is primarily [excitatory/inhibitory]
inhibitory (GABA), but some excitatory
Hyperdirect pathway is from ___ to ___ and is [excitatory/inhibitory]
cerebral cortex to STh, excitatory
Output from STh projects to ___ and is primarily [excitatory/inhibitory]
GP_i, excitatory (glutamate)
Main function of STh
modulates major output projections of basal ganglia (affects last stage of processing)
Rate model:
[True/false]: the rate model is a comprehensive explanation of basal ganglia function
false, it is the dominant view but has many flaws. Servers only as an initial framework
Rate model:
Role of the GP_i in rate model is to
tonically inhibit thalamus and motor activity
Rate model:
Motor activity requires [incr./decr.] in GP_i activity
decr
Rate model:
Direct pathway [facilitates/suppresses] movement
facilitates
Rate model:
Indirect pathway [facilitates/suppresses] movement
suppresses
Rate model:
net effect on striatum of increase in dopamine
decreased GP_i inhibitory output, therefore increased motor activity
- dopamine inhibits GABA/ENK spiny neurons, so increase GP_e output, decrease STh excitation of GP_i, thus decreasing GP_i
- dopamine excites GABA/SP spine neurons that inhibit GP_i
Basal ganglia model of movement selection
- basal ganglia used for movement selection based on value/reward
- dopamine neurons provide estimate of value/reward of an action
true (in the context of reward selection)
Lesions of STh produce
hyperkinetic dyskinesia (contralateral)
hyperkinetic dyskinesia
results in ballismus (wild exaggerated involuntary movements of limbs)
bilateral lesions of SNc produces
akinesia
Parkinson’s Disease:
Four main symptoms
- bradykinesia/akinesia
- rigidity
- rest tremor of 4-7 Hz
- postural instability
Parkinson’s Disease:
Main pathology
loss of pigmented cells in SNc
Parkinson’s Disease:
[incr./decr.] in GP_e activity
decrease
Parkinson’s Disease:
[incr./decr.] in STh activity
increase
Parkinson’s Disease:
[incr./decr.] in GP_i and SNr activity
increase
Parkinson’s Disease:
Hypothesized etiology
oxidative stress
Parkinson’s Disease:
Pharmacological treatment
L-DOPA
Parkinson’s Disease:
Side effects of L-DOPA
hyperkinetic movements
false, would predict involuntary movements that do not actually occur
Lesion of putamen produces (x2)
- obstinate progression
- sterotypic behavior
Bilateral lesion of caudate produces
changes in more complex behavior, eg
- compulsory approaching syndrome
- perseverative behavior
Huntington’s Chorea:
Pathology
- initial loss of spiny neurons in neostriatum (particularly GABA/ENK)
- also loss of cerebral cortical neurons
Huntington’s Chorea:
Symptoms
- involuntary movements (chorea and athetosis)
- dementia / personality changes