output: movement

output: movement

1. voluntary

   • conscious contro
   • strategies for cntrlling voluntary movements
     • ballistic movements (preprogrammes
       • Movement based largely on a set of pre-programmed instructions are called Ballistic movements
       • Rapid but at expense of accuracy – little opportunity for compensation for unexpected changes e.g. striking a cricket ball, returning a tennis serve
     • pursuit or bisual feedback movements
       • Motor command continually updated according to sensory feedback (e.g. visual)
       • Highly accurate (can be modified while in progress) but slow e.g. visual tracking
     • In practice most movements involve a mixture of both feedback and ballistic strategies
   • stages of voluntary movement
     • 1 intention 2 motor program 3 motor strategy 4 execution of movement
   • brain regions and movement
     • prefrontal cortex
       • intention
     • suplementary motor area and premotor area
       • planning
     • primarymotor cortex
       • origin of pyramidal triad i.e. motor map
     • basal ganglie
       • initiation of movement by putting motor plan into actin
       • effected in parkinson disease
         • DOPA, deep brain stimulation
       • input mainly from prefrontal cortex i.e. intent
       • Output: to pre-motor area (via thalamus)
     • cerebellum
       • motor learning and error detection

2. involuntary

   • automatic

3. skilled movement involves motor action and memory

   • declarative memory
     • factual information i.e. life events, consciously accessible
   • non declarative memory
     • procedural memory i.e. motor skills info is less easily formed and les easily forgotten, it is not available to sconsciousness

4. stroke

   • Paralysis and loss of sensation will be contralateral to the side of the haemorrhage

5. descending pathways for motor control

   • Fig. 14.18 from Bear et al “Neuroscience: Exploring the Brain” Lateral pathways (corticospinal and rubrospinal)
     • Pyramidal neurones in M1 project to the spinal cord (corticospinal tract) and red nucleus (rubrospinal tract) • Main function – control of voluntary movement e.g. distal muscles – fine control of hand
     • mainly control voluntary movement and distal muscle groups
   • ventromedial pathways
     • Control of axial (trunk) muscles – control of posture • Descending systems synapse on motoneurones or on interneurones in the spinal cord
     • Mainly control proximal and axial (trunk) muscles and maintain posture

6. motor neuron organisation

   • Skeletal muscle fibres are innervated by alpha- motoneurones
   • Motoneurones provide final common output
   • Each motor axon branches to innervate from 3 (e.g. ocular) to 1000 (e.g. gastrocnemius) muscle fibres
   • Motoneurone and the muscle fibres it innervates form a functional unit called a motor unit
   • Motoneurone pools of each muscle form columns in the ventral horn Collections of motoneurones in the ventral horn are also called motonuclei