L10 - Motor control concepts and motor cortex

Primary motor

Location, Role in voluntary mvm, somatotopic organisation

location

frontal lobe —> pre central gyrus

role

execute commands to motor neurons,

secondary motor area - premotor cortex

Location, Role in voluntary mvm, somatotopic organisation

location

frontal lobe —> anterior to the primary motor cortex

role

planning mvm (p=planning)

sensory input

spatial guidance

Primary motor

Location, Role in voluntary mvm, somatotopic organisation

location

frontal lobe —> pre central gyrus

role

execute commands to motor neurons,

secondary motor area - premotor cortex

Location, Role in voluntary mvm, somatotopic organisation

location

frontal lobe —> anterior to the primary motor cortex

role

planning mvm (p=planning)

sensory input

spatial guidance

Explain the differences between ‘reflex’ and ‘voluntary’ movements.

a) Describe the sensory contribution to learning and movement control.

b) Describe a stepping pattern generator.

Central Pattern Generator (CPG)

• neuronal circuit

• produce rhythmic motor patterns in absense of sensory/descending inputs that carry timing info

• initiated by higher centres (brainstem) modified by sensory input from PNS

Stepping pattern generators (SPG)

• active lower motor neurons to innervate pattern of alternating flexion and extension rd for walking

• output - adapted to …

  • task

  • environment

  • stage of walking cycle

Describe what is meant by the concept of ‘motor control’.

regulate and direct mechanisms pivotal to mvm

sensory info

proprioceptive

• receptions in periopheral NS

• info on weight bearing, limb position prior to mv

visual system

• visual cues for mvm and guidance during mvm

• vision to fixate on object, corrective adjustmend to achieve contact

vestibular system

• input form inner ear about head position relative to gravity and mvm

Define coordination and degrees of freedom

degrees of freedom

• humans have degrees of freedom that need ot be controlled

• inherent variability that is critical to optimal funciotn

Contrast different models of motor control including hierarchical model, ecological and dynamical systems approach

dynamic interplay btwn perception, cognition, action systems

hierarchial model

• organisation control that is top down

• limitation; cannot explain dominance of reflex behaviour eg stepping on smth fast

dynamic systems theory (DST)

• whole body as mechanical system

• variability as necessary for optimal fx rather than result of error'

• limitation; presume NS has less important role and mathematical formuals are dominant in motor control

ecological

• motor control evolved to cope w. environment

• suggests action rq perceptual info speciial to desired goal-direction action in speicifc environment

• limitation; less acknowledgement to structure and fx of NS

secondary motor area - supplementary motor cortex

Location, Role in voluntary mvm, somatotopic organisation

location

frontal lobe —> midline surface of the hemisphere anterior the primary motor cortex

role

feeds motor instruction in correct sequence esp in coordinated mvm

3 classes of mvm

reflexes

• involuntary

• rapid

• sterotyped

• eg; eye blink, coughing, knee jerk reflex

• inittiated by an eliciting sitmulus

rhythmic motor patterns

• combines voluntary and reflexive acts

• voluntary initiation and termination

• once initiated mvm repetitive and reflexive

• eg; chewing, walking, running

voluntary

• purposeful, goal oreinted

• learnt and can be improved

• process of planning, programming, execution

• complex actions; writing, speaking, playing piano