ANAT 321 Lecture Notes - Lecture 19: Substantia Nigra, Subthalamic Nucleus, Basal Ganglia

• School: McGill University
• Department: Anatomy & Cell Biology
• Course: ANAT 321
• Professor: David Ragsdale

Document Summary

Cortex is top of hierarchy of control of voluntary movements. But ability to make coordinated, complex movements also depends on basal ganglia & cerebellum. Green: caudate (lines lateral wall of lateral ventricle, long thin strip, down temporal lobe) & putamen. Substantia nigra: midbrain, black strips on either side; dopamine neurons that send axons to other structures of basal ganglia. Output of basal ganglia: internal segment of globus pallidus (gpi) Gpi always fires spontaneous ap at high frequency; inhibitory to thalamus thalamus excitatory to cortex excitatory back to putamen (basal ganglia) Inputs to basal ganglia are caudate & putamen, putamen movement of basal ganglia putamen has 2 sets of neurons that form 2 pathways: direct & indirect pathways. Direct pathway: putamen inhibitory (not spontaneously active) gpi (output neurons) relieves inhibition on thalamus thalamus can activate motor cortex (m1, premotor, sma) Direct pathway active increase cortex activity enhance movement.