PSL300H1 Lecture Notes - Lecture 30: Reciprocal Inhibition, Motor Neuron, Brainstem
Document Summary
Definition: network on interneurons, that coordinate interactions b/w different motor groups. Location: interneurons, of spinal cord & brainstem (and little in hypothamalus) Behavioural responses, locomotion, motor control: breathing, swallowing, walking. Restores proper states if posture is perturbed, reflexes are not complicated enough to restore homeostasis. Each phase is programmed by neural networks in the intermediate zone, of lumbar spinal cord. Properties: pacemaker neurons, diffuse excitation, reciprocal inhibition, phase-dependent reflexes. Achieved through the 2 cpg"s in each leg (flexor & extensor cpg"s) Organized into 2 half-centers (for each cpg: flexor burst generator flexor motor nuclei (leg flex, extensor burst generator extensor activation (leg extension & stance) Mutually inhibitive: when the flexor burst is on, extensor burst is off. No leg movement both spontaneously active: spontaneously active, when not inhibited (default state on) Fixed duration (0. 25-3ms: regardless of speed of locomotion. Build-up of inhibition stops the ap"s ends flexor motoneuron activation. Reciprocal inhibition of extensor stops: therefore extensors on.
