Basal Ganglia Flashcards
What is the pyramidal pathway?
The executor pathway
What is another name for the extrapyramidal pathways?
The accessory pathways
What are the components involved in the extrapyramidal pathways?
basal ganglia (complex motor actions), cerebellum (movement coordination), reticulospinal and vestibulospinal tracts, corticorubrospinal system
What does basal ganglia refer to?
a large and functionally diverse set of nuclei that lies deep within the cerebral hemispheres
What are the 5 nuclei that compose the basal ganglia?
Caudate
Putamen
globus pallidus
substantia nigra
subthalamus
“Can Peter Go Sell Soup
What does the Basal ganglia do to influence movement
It regulates the activity of upper motor neuronal circuits:
regulate muscle contraction
force initiation and termination of movement
regulate multi-joint movement
control movement sequencing
oculomotor control
motor habit learning
What are some of the complex patterns of motor activity that the basal ganglia controls?
writing
using scissors
throwing balls
shoveling dirt
some aspects of vocalization
What is the input zone of the basal ganglia?
The striatum composed of the caudate and putamen
What does the striatum do?
Receives and process movement related signals from the cerebral cortex and substantia nigra pars compacta
What are the main neurons of the caudate and putamen and what neurons do they contact?
Main neuron are the medium spiny neurons (inhibitory, GABA)
Contact neurons of the globus pallidus and the substantia nigra pars reticulata
What is the pathway of the output zone of the basal ganglia from the globus pallidus ?
neurons of internal segment of globus pallidus (inhibitory) ==> ventral anterior and vetral lateral complex nuclei of thalamus (excitatory) ==> motor cortex on the frontal cortex (upper motor neurons)
What is the pathway of the output zone of the basal ganglia from the substantia nigra pars reticulata ?
neurons of substantia nigra pars reticulata (inhibitory) ==> superior colliculus (excitatory) that command head and eye movement
Why do the efferent cells of globus pallidus internal and substantia nigra pars reticulata have high levels of spontaneous activity?
To prevent unwanted movement by tonically inhibiting cells in the thalamus and superior colliculus
What does the direct pathway of the BG system do?
serves to release the thalamic neurons from tonic inhibition practiced by the globus pallidus to facilitate the initiation of voluntary movement
What does the indirect pathway of the BG system do?
serves to increase the level of tonic inhibition of the thalamic neurons in order to prevent unwanted movement
