Latency responses Flashcards
what does a short latency reflex (SLR) include
spinal processing only
how much control do we have over SLRs
very little
how can we control SLRs
decrease - inhibition sent from M1 adn synapsing onto inhibitiory interneurons to relax the msucle
increase - increase background activity in the muscle to increase the size of MUs activated
what are SLRs sensitive to
background EMG activity
- high background activity = higher amplitude
rate of muscle stretch
- large stretch = higher amplitude
what is an example of an SLR
knee jerk reflex / monosynaptic reflex
what is a long latency response (LLR)
polysynaptic reflex
spinal and cortical processing
- large range in time due to differences in length to get to the brain
what are the properties of an LLR
recruits the same areas as voluntary motor actions
can be manipulated depending on desired task
show flexible and goal directed processing
how do LLRs change depending on the task
can increase responses reaching to smaller targets when perturbed vs reaching to large targets
EMG responses are larger to crrect back to small target vs large target
LLR can increase when the goal is to resist an expected perturbation
how long does each latency response take
SLR = 20-50ms
LLR = 50-105ms
VOL = 100+ms
what types of feedback do voluntary responses use
spinal, cortical, and visual feedback
why are voluntary repsonses slower than SLRs, and LLRs
vision and visual processing is slow
how long does a voluntary repsonse to perturbation (muscle stretch) take
120-180ms
where are goal directed feedback responses generated
M1 - primary motor cortex
what happens to M1 responses during perturbations
responses are larger when the hand is pushed away from the target and must get to the target on time
increased firing in M1 later in the LLR when visual input gets integrated and there is more time to process
when can a SLR be manipulated
when we know when, where, and how strong the perturbations will be
