Basal Nuclei- added paths Flashcards
What structure is similar in structure and function to GPi?
substantia nigra pars reticulata
What are the fibers called from the striatum to the pars reticulata?
striatonigral fibers
What does the pars reticulata inhibit?
the VA/VL thalamus with GAGAergic inhibitory neurons
What do neurons of the pars compacta release?
Dopamine (DA)
What are the two actions that dopamine produces on the striatum?
- inhibition via D2 receptors of the indirect pathway
2. excitation via D1 receptors on the striatal neurons of the direct pathway
With both actions of the SNc, what does it promote?
thalamic excitation.
neurons of the SNc are inhibited by ______, but excited by _______
- striatal GABAergic input
- cholinergic input from pedunculo-pontine nucleus (PPN)
What is the other role in movement that the PPN has other than facilitating disinhibition of the thalamus?
it is one of the brainstem nuclei that contributes to the pontine reticulospinal tract (therefore it can produce descending excitation of the spinal LMN)
What are the four parallel channels of functions involving the basal nuclei?
- Motor channel
- Oculomotor Channel
- Prefrontal channel
- Limbic channel
What is the motor loop associated with?
regulation of voluntary movement
What does the motor loop arise from?
supplementary motor cortex and other cortical areas
What does the motor loop regulate?
VA/VL thalami and motor cortex excitability via connections through the putamen and the GPi(direct) and the GPe and subthalamus (indirect_
SMA generates readiness that precedes what movements?
volitional, self paces, voluntary
Functions associated with the motor channel include?
- initiated by the intention to act
- preparation, organization and execution of action
- endogenous generation of responses when environmental stimuli fail to provoke responses
What is the oculomotor channel associated with?
regulation of eye movements