Action Planning

Question 1

action selection generally occurs across which motor structures?

Answer 1

parietal cortex
premotor cortex
supplementary motor cortex (SMA)
basal ganglia
many other non motor areas like the frontal lobe

Question 2

parietal and premotor cortex

Answer 2

play a role in representing action plans relating to external objects

parietal- maintains activity in diff regions for reaching, looking & grasping
motor intention

responsible for translating from “eye-centered” reference frame to “hand-centered” reference frame

Question 3

stimulation of parietal and premotor cortices

Answer 3

parietal- produce the desire to move, and invoke a belief that one has moved, in the absence of movement

premotor- results in actions, in the absence of feeling intention or awareness of the action

Question 4

more premotor cortex

Answer 4

heavily connected to parietal cortex- extension of the dorsal stream

involved in externally guided action

involved in translating perception into action

Question 5

supplementary motor area (SMA)

Answer 5

heavily connected to the frontal lobe

involved in internally guided action

involved in coordinating actions that occur in a sequence, and coordination bet hands (e.g. tying shoes, playing piano, driving stick)

involved in preparation and initiation of action
–>selection of action based on internal goals or experiences

potential inhibition of undesired actions

Question 6

lateral premotor cortex

Answer 6

codes for actions and their goals

neurons in this area are active during grasping in light or dark

they respond to a specific type of grasp–> this causes similar neurons to remain active when objects are grasped in the same way

Question 7

alien hand syndrome

Answer 7

correlated with lesions in SMA

will reach out and grab objects without a desire or reason

Question 8

readiness potential

Answer 8

a slow negative potential in EEG that precedes involuntary movement –> thought to represent preparation for movement before action begins

can occur as early as 300 ms before the urge or intent to want to move

Question 9

Benjamin Libet clock study

Answer 9

demonstrated the readiness potential

suggested that it is possible to perform movements with no explicit knowledge

Question 10

direct pathway in basal ganglia

Answer 10

striatum –> globus pallidus(int.) –> substantia nigra –> thalamus –> cortex

faster pathway

inhibitory on output nuclei(inhibitory)–> excites action

Question 11

indirect pathway in basal ganglia

Answer 11

striatum –> globus pallidus(ext.) –> subthalamic nuclei –> globus pallidus(int.) –> sub nigra –> thalamus –> cortex

slower pathway

excitatory on output nuclei (inhibitory)–> inhibits action

Question 12

more basal ganglia

Answer 12

dopamine projections from substantia nigra contribute to action selection by exciting the direct pathway, and inhibiting the indirect pathway

baseline=strong inhibition

as one plan preferred, inhibition decreased –> allows for execution of plan/movement

Question 13

affordance-competition hypothesis

Answer 13

the idea that actions (i.e. affordances) compete for selection, and whether or not that action becomes selected depends on a variety of factors, such as height, weight, environment, age, and other contexts

action selection (what) and specification (how) occur simultaneously and continuously within an extended motor network

sensory info used to constantly specify and update affordances

Question 14

affordance-competition in premotor cortex

Answer 14

when one plan out of a few is selected, the population of neurons in this area get excited dramatically for the selected plan, and inhibited for the others

Question 15

mirror neurons

Answer 15

same neuron will fire in PMC when performing an action, as when observing it in someone else

indicates a link between perception and action

expertise studies show that mirror neurons more active when viewing an action in our area of expertise as compared to other areas we are not experts in