Lec 17 Flashcards
What is presynaptic inhibition
Selective inhibition of only the presynaptic neuron.
Describe the axo-axonal synapse used for presynaptic inhibition, and through what mechanism it works.
What does this help us do?
Axo-axonal synapse is when an axon attaches to another axon (at end) before the synaptic cleft.
Can reduce the charge of act pot before terminal and reduce Ca2+ influx causing a reduced release of neurotransmitter. Does this by Cl- coming in causing decreased charge
Helps us fine tune our responses
How fast are longer-latency reflex responses compared to voluntary reaction time and monosynaptic reflexes
Slower than mono
Faster than voluntary
What is the significance of longer latency reflexes, what are they good for?
Give example of how you can voluntarily control them
They involve pathways that pass through brainstem or cortex
can give us more precise adjustments to stimuli and take into account context.
If told to respond to something, you will increase reflex amplitude. If told not to respond will reduce reflex. Then obviously if told to do something, then will have voluntary reaction, but if told not to, will not.
Where do longer-latency reflexes go? What research has proved this.
They go to the brainstem and cortex.
This can be proven with people who have mirror-movement syndrome. This is where action in one limb is mimicked in the contralateral limb. EMG will show a stretch reflex in ipsilateral limb, then the longer latency reflex happening. In the contralateral limb, you will see only the longer-latency reflex meaning that it travelled using a different pathway (supra-spinal pathway)
