models of motor control Flashcards
what is the stretch reflex ?
keeps the muscle in a desired length
muscle acts a a spring
what’s the role of the alpha neuron in the stretch reflex ?
causes muscle contraction
what’s the role of the gamma motor neurone in the stretch reflex ?
adjusts sensitivity of the reflex
allows muscle to contract until reach desired length
what is Sherrington’s reflex hypothesis ?
moments are obtained by combining stretch reflexes
brain sets desired length of springs and can be triggered without central supervision
when movement is generated by stretch reflexes what does this mean ?
hyopthesis 1
sensory afferent
what does the gamma motor neurone drive do?
hypothesis 2
proceeds the movement
- alpha neuron drive
gamma detects
alpha acts
what was found when the spinal cord of a monkey was disconnected?
they can still reach visual targets accurately without view of limbs
quality of pointing was worse than monkeys intact
movement is not a reflex
what does microneurography record?
muscle spindle discharges
what does the reflex hypothesis assume about the feedback control system?
movement is generated by sensation
delay makes the system unstable
what is the equilibrium point hypothesis ?
the brain controls a virtual equilibrium point to control the reaching movement
no reflexes involved
what are the main assumptions of the equilibrium point hypothesis?
brain only cares where the arm should be not where the arm actually is
brain doesn’t care about the forces as long as final configuration can be reached
what is equifinality
brain only cares about equilibrium and final configuration
what Is signal dependent noise in terms of muscles?
movement causes noise which depends on the control signal
more abrupt and bigger movement makes more noise
more variability means more noise
what is optimal feedback control ?
assuming,es brain keeps feedback policies for diff motor skills
reduces errors compared to only having plans
