The Basal Ganglia Flashcards
What is the Basal Ganglia?
A group of neuronal cell bodies in the white matter of cerebrum.
What are the 5 nuclei that make up the Basal Ganglia?
Caudate, Putamen, Globus Pallidus, Subthalamic nuclei and the Substantia Nigra.
What are it’s inputs and outputs?
Inputs - Cerebral cortex
Outputs - Cerebral Cortex via the thalamus, the globus pallidus connects to the Reticular formation and Vestibular nuclei.
What are it’s input nuclei?
Caudate and Putamen
What are it’s output nuclei?
Globus Pallidus and Substantia Nigra.
What is the function of the Basal Ganglia?
Acts as a ‘brake’ to selectively inhibit and modulate the effect of the Thalamus which is excitatory to the cerebral cortex. It therefore prevents unwanted movement and initiates/terminates voluntary movements. It also has a role in the motor planning stages of movement with the Pre and Supplementary motor cortices.
What structures does the Globus Pallidus act on? What happens if these pathways are disrupted?
The Reticular formation and the Vestibular Nuclei. If these pathways are disrupted there could be excessive contraction, causing hypertonicity (the name given to a higher than normal amount of tone in the muscle - seen as rigidity in Parkinson’s and spasticity in stroke.
What occurs if there is too much inhibition from the BG?
Hypokinetic disorders such as Parkinson’s
What happens if there is too little inhibition from the BG?
Hyperkinetic disorders such as Huntington’s
Does the basal ganglia receive feedback of ongoing movements?
Yes - as the sensory afferent pathways link to the Cerebral cortex, and the spinocerebellar pathway to the cerebellum which connects to the cerebral cortex. The cerebral cortex communicates with the basal ganglia through the input nuclei, the caudate and putamen - thus being able to continue to modulate movements to increase/decrease inhibition.
