10.28.2009 - Hochman on CPGs

V0 population of interneurons necessary for righ-left coordination in walking
V1 population still get locomotion, but you slow down in walking
V2 disrupts left-right coordination - don't get locomotion - drive commisural connections from brainstem to spinal cord
Hb9 interneurons activate after the motor-neurons fire
V3 spinal neurons also disrupt the rhythm
No explicit population that is necessary for the CPG, therefore the CPG is an emergent phenomena
How do these experiments actually work? Does it require "feedback" for the rhythmicity? Perhaps physical enervation can help to drive the circuit?
Think that the CPG is in the ventral spinal cord
Feedback is required? Removing afferents appears to abolish locomotion.
Primary afferents and descending systems not required?
Lack of glycinergic or GABAergic transmission still has oscillation in fictive patterns
Lack of glutamatergic transmission still get oscillation in fictive patterns
Cholinergics are required for walking because flexor/extensor are coactive.
There appears like there is an external clock keeping time for the CPG
Swimming to walking consists of completely different populations of neurons in lamprays
The clock may come from sympathetic nervous system
Left then right flexor occurs with low level stimulation