action Flashcards
difference between extensors and flexors
extensors extend a joint
flexors contract f
what 3 parts of the NS does action focus on
somatic - moving limbs on purpose
autonomic - unconscious inner body action
internal actions - switching thoughts
why is action an inverse problem
you start with a goal, and figure out what sequence of actions you can take to accomplish it
this chapter we went from top to bottom of action through diff brain and body structures - list them top to bottom
start with motor cortex
premotor and supplementary motor areas in prefrontal cortex
basal ganliga role in initiation
cerebellums role in coordination
spinal cord
muscles
what is motor equivalence
the ability to use different movement produced by either the same or different parts of the Boyd, to perform a task under different conditions
forward model
what will come of the result if I perform an action?
feed forward control
come up with a motor command, send it to muscles to perform, and that’s it - hope for the best.
fast but less accurate, so you may use it when speed is the most important thing
feedback control
come up with a motor command to send to muscles, perform action and compare what actually happens to what you were hoping was gonna happen
If you detect errors, you revise the motor command. Not just send commands and hope for the best, there is a continuous feedback loop of adjustment
slower but more accurate
if the input is the goal and the output is the motor command - what kind of model is it
inverse model
is feedback control an inverse model?
yes because it starts with goal state, and motor command as output. but through visual sensory we compare what happens with our goal and adjust if necessary - this part is a forward model
what common household item is a feedback control system
thermostat - tries to reach a heat, compares goal to actual temperature, simple feedback loop that makes adjustments
what role does the premotor cortex play
cognitive function - what my goal is and how will I accomplish that goal
high level goals and action planning
how long before an action occurs can we see planning activity (readiness potential) in the ipsa or contra lateral hemisphere premotor cortex
what about when they consciously note the decision to make the movement
contralateral because opposite sides control each other
as much as a second before movement occurs
when they consciously report to making the decision, the premotor cortex has already become active
the monkey study with spatail cues shows brain activity when monkey is planning for 2 actions - explain
has to pick one colour or the other based on the cue, neyrons are tuned to diff directions of movement
- baseline - all fire at same level
- sees which 2 movements it may have to do - these two start to fire more simultaneously
-cues disappear while memory is held in mind, neurons continue to fire
-cue of which movement to make is shown, one increases firing rate, and the other is inhibited below baseline
- knows what action to take but waiting for the go, neurons ramp up in preparation
- go cue, neurons have final burst to make the movement
what controls initiation or inhibition of movements
basal ganglia
how does BG initiate or inhibit movements
Cortico BasalGanglia Thalamo Cortical Loops
start in cortex, descend to BG, go to Thal, and then back to cortex
how does the BG know whether to initiate or inhibit a movement,
what else is it used for initiating besides motor actions
Reinforcement learning based on Dopamine from Substantia Nigra
also helps us switch thoughts or update memories, control emotion, relax or take action
