L18 Flashcards
what is reciprocal inhibition
antagonist limb muscles are innervated in a way that permits smooth unimpeded muscle response
How are renshaw cells activated
by alpha motor neuron collateral branches
how else do renshaw cells get input
they receive input also from descending pathways (descending control of aMN excitability)
what do renshaw cells feed back onto
aMN from the same MN pool and onto gamma MN that supply spindles located in the same muscle
to aMNs and gamma MN of synergists
Ia inhibitory inter-neurons
what type of feed back loop do these cells provide
negative feedback loops
what can renshaw cells control and why
reciprocal inhibiton due to their ability to feed back onto the Ia inhibitory inter neuron
increased or decreased activation of RC will increase force resolution
increased activation
what are the three ways to alter the strength of spinal reflex
cell body of the alpha MN
interneurons in reflex pathways
pre synaptic connections to the sensory afferents
how is the strength of spinal reflex altered by the cell body of the aMN
through EPSPs and IPSPs
how does interneurons in the reflex pathway alter the strength of the spinal reflex
inhibitory and excitatory interneurons (Ib interneurons)
reciprocal inhibtion (Ia)
recurrent inhibtion (Renshaw cells)
where does the presynaptic connection occur on the neuron
connection on the presynaptic neurons bouton
what is altered in presynaptic inhibtion
amount of Ca2+ that enters the bouton
and volume of neurotransmitter released by the presynaptic neuron
what is the result of the decrease in neurotransmitter released
decreased postsynaptic response
what is it that is released from the presynaptic neuron that decreases Ca2+ influx
GABA
what are the two types pathways for preprogrammed reactions or reflexes
M1 = monosynaptic
M2/M3 = motor cortex
