Control of Movement (3) Flashcards
What are the roles of the cerebellum in movement?
Timing - affects control of agonist and antagonist muscles
Motor learning - strengthens input-output connections
Coordination - coordinates muscle activity in multiple joints - compares intended and executed movements
What are the inputs to the cerebellum?
Mossy fibres
Climbing fibres
Where do the mossy fibres into the cerebellum originate and what types of information do they relay?
Spinal cord - proprioceptive
Pontine nuclei - cortical info. and copies of motor commands before carried to spinal cord
Reticular nuclei - ascending and descending info.
What is the general structure of cerebellar circuitry?
Mossy fibres synapse onto granule cells - send parallel fibres to Purkinje cells
Climbing fibres from inferior olive in brainstem - synapse onto Purkinje cells - involved in learning
What are the output cells of the cerebellum and what is their effect?
Purkinje cells
Inhibitory
What are the roles of the basal ganglia in movement?
Movement control
Postural maintenance
In which layer of the cerebral cortex do the corticospinal tracts originate?
Layer 5
In what way is there task dependence of corticomotor neuron firing in the motor cortex?
Precision grip - increased firing
Power grip - low level firing - no increase
What are the 4 main motor cortical areas?
Supplementary motor area
Premotor cortex
Cingulate motor area
Primary motor cortex
What are the role of the SMA?
Reciprocal connections with basal ganglia
Planning learned movement sequences
What is the role of the premotor cortex?
Receives inputs from cerebellum
Planning visually-guided movements
Bilateral hand movements
Movements depending on visual cues
What is the role of the cingulate motor area?
Imagined movements
Signal-triggered movements
What is the role of the primary motor cortex?
Controlling muscle groups
What is the evidence for the involvement of the SMA in motor planning?
Imagined movement causes SMA activation
Executed movement causes SMA and M1 activation
Where does the readiness potential occur before movement?
Motor cortex and SMA
What are the two processing streams of the premotor cortex and what are their roles?
Ventral - object processing - e.g. shape, size, colour
Dorsal - spatial processing - e.g. location, movement, spatial relations
Do all of the corticospinal projection neurons originate in M1?
No
What is the role of the ipsilateral corticospinal tract fibres?
Fractionated movements - e.g. independent finger movements
What are the roles of the corticospinal tracts?
Descending control of afferent inputs - synapses onto alphaMNs and interneurons in spinal cord
Gating and gain control of spinal reflexes
Direct and indirect MN excitation
Dextrous movements
