Topic 4 Action pt 1 Flashcards
What is action?
- change the environment
- somatic (skeletal mm moves limbs)
- autonomic
- internal to CNS
What is an example of internal action to CNS
updating memory: holding a phone number in our minds and then updating it to change it to the right phone number
switching tasks: studying one subject then studying another subject right after
What is the problem with action and why is this important?
problem: how to effect change in the world
importance: necessary to achieve goals (eat, drink, reproduce, survive)
Action: inverse problems
planning which actions to take in order to achieve goals
inverse model
- current position and desired position
- > motor command
- used to create motor plan
used to create motor plan
inverse model
forward model
- current position and motor command
- > predicted position
- used to evaluate motor plan and/or action
Carson is playing the piano. Which part of the brain is he using the most to do these movements?
supplementary motor cortex
feedforward control uses ______
feedforward model uses inverse model
feedback model uses ______
feedback model uses both inverse model (because it has a feedforward controller) as well as the forward model (because it uses comparator)
what part of the brain is responsible for initiation and termination of movement
basal ganglia
actuator
to cause something to operate or to activate something (muscles)
Which homunculus has bigger area for the hand? somatosensory or motor?
motor
how does using top down and bottom up processing help?
probably helps speed things up
function of brainstem centers
basic movements and postural control
Supplementary motor cortex is ____ to primary motor cortex and ______ to premotor cortex
Supplementary motor cortex is rostral to primary motor cortex and dorsal to premotor cortex
What is it called when we are able to write the same sentence despite using different mm groups?
motor equivalence
current position and desired conditions
-> motor command
inverse model
current position and motor command
-> predicted position
forward model
efference copy
internal copy of a motor command
Faster but less accurate (feedforward or feedback control?)
feedforward control
feedback control (4 points)
- motor control sent to mm
- actual state compared to desired state
- adjustments made based on errors
- slower, but more accurate
feedforward control (2 points)
- motor command sent to mm
- faster, but less accurate
Quench thirst
goal
drink from cup
conceptual level
pick up cup from right hand
effector level
activate appropriate mm in arm
implementation level (actuator is mm)
supplementary motor cortex
- involved in selecting goals and planning actions at a conceptual level
- particularly when plans involve internally generated sequence of actions
- keeps track of where we are in the sequence
peristimulus time histogram
shows action potentials during individual trials as well as histogram of action potential firings over time (recordings from SMA allows us to know that neurons fire in anticipation of a sequence of events)
When do neurons fire in the SMA?
- some neurons fire in anticipation of a sequence
- some neurons fire in anticipation of a particular action in a particular sequence
- some neurons fire in anticipation of the next particular action (could be any action, such as the 3rd action of any sequence of movement)
what does injecting muscimol do to the SMA?
- GABA agonist to manipulate SMA
- animal trained to already do particular sequence of actions is injected with muscimol to SMA
- injecting muscimol turns off this brain area temporarily
What happened to the primates ability to do a learned sequence when their SMA was inhibited ?
Although the primates could still do cued sequences, the primates made a lot of mistakes when they were asked to do a learned sequence
True or False: The motor cortex represents specific mm actions
false: the motor cortex represents directional movements of body parts, not the specific mm actions
Signals from motor cortex travel directly to ____
signals from motor cortex travel directly to lower motor neurons and lower circuit in the brainstem and spinal cord
motor cortex activity is related to ____
movement direction
response rate as a function of direction of movement can be summarized by a
tuning curve
In a population vector, what does the length of the arrow mean?
long arrow: relative rate of firing increases, increase intensity
short arrow: relative rate of firing decreases, decrease intensity
population vector
accurately represents actual movement direction
do population vectors represent the action has been taken?
no, population vectors are plans of the movement.
first we are given a cue, then neurons fire (population vector), then the “go” signal is given
basal ganglia function
- help select, initiate, and inhibit movements through cortico-basal-ganglia-thalamocortical loops
- dopamine based reinforcement learning
- participate in motor control, cognitive control, and emotional control
Direct pathway
- Cortex
- striatum
- GPi/SNr
- Thalamus
- Cortex
Indirect pathway
- Cortex
- Striatum
- GPe
- STN (subthalamic nucleus)
- GPi/SNr
- Thalamus
- Cortex
Hyperdirect pathway
- Motor cortex
- STN
- Thalamus
- Cortex
Where is the dopamine signal coming from?
substantia nigra pars compacta
The _____ is activated by external stimuli whereas the _____ is moreso activated by internal stimuli (sequence)
The premotor cortex is more activated by external stimuli whereas the SMA is more activated by the internal stimuli
what is reponsible for reflex coordination?
local circuit neurons (interneurons in the spinal cord)
the striatum (inhibits, excites) _____ the _______ via the indirect pathway and (inhibits, Excites)_______ the ________ via the direct pathway
the striatum inhibits the GPe in the indirect pathway and inhibits the GPi/SNR via the direct pathway
