Subcortical control of movement (BG) Flashcards
What are the motor components of the BG?
Caudate nucleus, internal capsule, putaman and globus palidus, subthalamic nucleus (STN)
What is the striatum?
Caudate nucleaus, putaman and globus pallidus
Where does the striatum get input from?
Sensorimotor cortex, limbic system, association cortex, thalamus, Raphe nuclei, and SNc
Where does the STN get input from?
Frontal cortex (hyperdirect pathway)
What are the two major pathways?
Direct (movement) and indirect (prevents movement)
What types of neurons innervate the BG?
Glutamatergic: corte, thalamus, STN
GABA: striatum, GPE, GPI, SNr
Dopamine: SNc
What does inhibition of inhibition cause, and what is it called?
It’s called disinhibition, and causes excitation
Describe how the nerve cells are arranged in the disinhibitory circuit of the BG.
Excitatory neurons from cortex –> inhibitory neurons in striatum –> inhibitory neurons in globus pallidus –> excitatory neurons in VA/VL of thalamus –> motor cortex
Describe the direct pathway.
Disinhibition:
Cortex/SNc –> caudate/putaman –I globus pallidus/SNr –I (motor areas in brainstem) + VA/VL of thalamus –> frontal cortex
Describe the mechanisms for action selection in the direct pathway.
Lateral inhibition in striatum from activated cells inhibit other striatal cells
Describe the indirect pathway.
Cortex –> STN –> GPi/SNr –I motor areas
Dopamine released from SNr prevent movement
True or false: direct and indirect pathway is activated simultaneously.
True: to promote wanted movement, and prevent unwanted
Describe the hyperdirect pathway.
Cortex –> STN –> GPi/SNr –I motor areas in the brainstem + VA/VL of thalamus
How are the direct and indirect pathways functionally organized?
Center-around
How does the degeneration of dopaminergic neurons in Parkinson’s disease affect voluntary movement?
Reducing it
