Motor Overview Flashcards
Define voluntary behaviour.
The physical manifestation of an individual’s intention to act on the environment.
Define sensorimotor transformation.
The brain transforms a goal into motor commands to achieve that goal.
Name the three theoretical models for the neural basis of voluntary movement.
Traditional.
Dynamic causal.
Optimal feedback control.
Describe the traditional model of voluntary movement.
Uses representations of the external world to execute pre-planned sequences of movement.
Any disruptions would result in failure.
Describe the dynamic causal model of voluntary movement.
Motor control circuit adaptability allows for real-time adjustments, but most useful for repetitive movements.
Describe the optimal feedback control model of voluntary movement.
Combines visual and proprioceptive information to execute movement.
Uses real-time feedback to execute real-time adjustments.
What are the three key processes involved in the dynamic causal model of voluntary movement?
State estimation.
Task selection.
Control policy.
Explain the process of state estimation.
Uses copies of motor commands and sensory feedback to estimate the present state of the body and the environment.
Explain the process of task selection.
The brain chooses a behavioural goal in the current context and what motor actions might best attain that goal.
Explain the process of control policy.
Provides the set of computations that establish how to generate the motor commands to attain the behavioural goal given the present state of the body and the environment.
Describe Brodmann’s area 6.
It is divided into 5 or 6 functional areas involved in the planning and control of motor actions.
Where are the arm-control regions in Brodmann’s area 6?
Dorsal premotor cortex (PMd).
Predorsal premotor cortex (pre-PMd).
Where are the hand-control regions in Brodmann’s area 6?
Ventral premotor cortex (PMv).
Where are the supplementary motor areas in Brodmann’s area 6?
Supplementary motor area proper (SMA) = caudal.
Presupplementary motor area (pre-SMA) = rostral.
Where is the primary motor cortex (M1) located?
Brodmann’s area 4.
Where is the primary somatosensory cortex located?
Anterior postcentral gyrus.
What is the role of the S1?
Processes mechanoreceptor signals from the periphery and transmits that information to other cortical regions.
What is the pyramidal tract?
A key descending pathway for voluntary control.
Where does the pyramidal tract originate?
In the cortical layer V in a number of precentral (M1, SMA, PMd, PMv and cingulate motor areas) and parietal areas.
Where do the axons of the pyramidal tract travel to?
Axons terminate in brainstem motor structures (corticobulbar tract).
Axons project down to the spinal cord (corticospinal tract).
What does CST stand for?
Corticospinal tract.
Describe the lateral CST.
Axons originate in one hemisphere and decussate at the pyramid in the caudal medulla. They then project to the spinal cord.
Describe the ventral CST.
A small portion of axons do not decussate.
In mammals, where do many CST axons terminate?
Terminate only on spinal interneurons and exert their influence on voluntary movement indirectly through spinal interneuronal and reflex pathways.
