Lecture 16: Basil Ganglia Flashcards
The basal ganglia consist of five paired structures that include:
the globes pallidus, the putamen, the caudate nucleus, the subthalamic nucleus, and the substantial nigra
What is the importance of the basal ganglia
for control of voluntary movements (inferred mostly from clinical observations)
Disorders of the basal ganglia can cause____.
excessive involuntary movements to movement poverty and slowness, typically without paralysis.
The _____ and the _____ are the sites of almost all afferent inputs to the basal ganglia
caudate nucleus and the putamen
Much of the input comes from different areas of the cerebral cortex; other input comes from _______.
nuclei of the thalamus
Direct Pathway: Projections from the cortex onto the ______ and _______. Project directly onto thalamus and back to cerebral cortex
GPi (internal globus pallidus) and substantia nigra.
Direct Pathway: Direct Loop has _____________on cortical neurons (positive feedback)
net excitatory effect
Direct Pathway: Believed to play a major role in the control of ________.
limb movements
Indirect Pathway: Projects from the cortex onto the _______, then to the _______.
GPe (external); subthalamic nuclei
Indirect Pathway: Indirect loop has a ___________ on cortical neurons (negative feedback)
net inhibitory effect
Indirect Pathway: Believed to play a role in __________.
oculomotor control
Direct and Indirect loops contribute to the _________.
motor circuit of the basal ganglia
Most of the thalamic projections to the cortex are directed to the ______.
premotor cortex and the supplementary motor area
Connectections within the cortico-basal-thalamo cortical loop are mostly____.
inhibitory
Hypothesis of BG: They disinhibit ares of the ________ and thus allow movement to occur. (not well supported)
motor system
