Peterson - Basal Nuclei Flashcards
striatum
- caudate nucleus
- nucleus accumbens
- putamen
lenticular nucleus
- putamen
- globus pallidus (external and internal segment)
substantia nigra (dark segment)
- compact - pigmented nuclei; dopaminergic regulation
- reticular - basal nuclei outputs
general inputs and outputs
basal nuclei help control motor functions
- excitatory input to striatum and subthalamic nuclei using glutamate
- inhibitory output by internal globus pallidus and substantial nigra to thalamus using GABA
- excitatory output from thalamus to cerebral cortex using glutamate
striatum connections
job is to inhibit globus pallidus and substantia nigra when receiving excitatory inputs from cortex and thalamic nuclei and dopaminergic input from substantial nigra
parallel loops
striatum receives different input
- association cortex –> caudate nucleus
- sensorimotor cortex –> putamen
- limbic area –> nucleus accumbens
connections to GPe
- excitatory inputs from subthalamic nuclei
- inhibitory outputs to striatum, GPi, SNr, and STN
connections to GPi and SNr
- inhibited if receiving inputs from striatum
- excited by STN to go on to inhibit thalamus
- inhibitory effect to thalamus when activated
connections to STN
excited by cortex –> excitatory outputs to GP and and SNr
-inhibited by GPe
direct pathway
removes inhibition on thalamus
-striatum inhibits GPi –> remove inhibition on thalamus causing it to excite cortex
indirect pathway
keep default inhibition on thalamus
-striatum inhibits GPe –> remove inhibition on STN causing excitation of GPi –> inhibit thalamus
dopamine effects - indirect vs. direct
- activator in direct path and inhibitor in indirect path
- both paths increase muscle movement
1. direct - dopamine binds to D1 activating inhibitory neuron –> inhibit GPi –> less inhibition on thalamus –> excite muscles
2. indirect - dopamine binds to D2 inhibiting inhibitory neuron –> less inhibition on GPe –> inhibit STN –> less excitation of GPi –> less inhibition on thalamus –> excite muscle
hemiballismus
uncontrolled movement of one arm and leg due to lesion in contralateral sub thalamic nuclei
-damage STN –> do not excite GPi –> more active thalamus
Huntington’s
neural degeneration of striatum –> uncontrolled movements (chorea)
Parkinson’s disease
reduce pigmentation of substantia nigra compacta –> reduce dopamine –> more inhibition on thalamus –> less muscle movement
-treat with L-dopa or unilateral pallidotomy
