21 Adaptations to Practice.docx

Practice

Aimed at improving movement production and information processing used to perform motor skills

• Primarily involves neural adaptations (plasticity) 

  • Working in two-walls, learning new footwork

• Can also induce muscular and metabolic adaptations

Training

Aimed at improving physiological functioning and physical abilities involved in performing motor skills 

• Primarily involves muscular and metabolic adaptations 

  • Mel’s drill, getting up quickly to make a wall

• Can also induce neural adaptations (plasticity)

Neuron Structure

Interneurons in the brain and spinal cord have a cell body, dendrites, and axons

Neurotransmission

Uses chemicals to transmit signals from axons to dendrites 

Neurotransmitters

Chemicals used for neurotransmission

Synapses

Spaces between axon terminals and dendrites

Presynaptic neurons

Initially release neurotransmitters into synapses

Postsynaptic neurons

Have receptors that bind neurotransmitters

Neurotransmission (Series of events)

• Action potentials travel down presynaptic axons to axon terminals 

• Neurotransmitters are released from vesicles located in axon terminals 

• Neurotransmitters diffuse across synapses to postsynaptic dendrites

• Neurotransmitters bind to receptors located on postsynaptic dendrites

• Ion channels open to allow electrical current to flow in postsynaptic dendrites

Excitatory postsynaptic potentials (EPSPs)

Occur when currents produce depolarization (excitation)

Inhibitory postsynaptic potentials (IPSPs)

Occur when currents produce hyperpolarization (inhibition)

Postsynaptic APs

Occur when the electrical potential of a neuron reaches an all-or-none threshold (around –50mV)

Spatial summation

Involves summation of both EPSPs and IPSPs that across at different synapses located close in space (one-time, multiple spots)

Temporal summation

Involves summation of either EPSPs or IPSPs that occur close in time at the same synapse

Plasticity

• Adaptations of neural structure and function due to experience 

  • Adaptations induce transient and persistent changes in neurotransmission

    • Increased release of neurotransmitter by presynaptic neurons

    • Increased number of neurotransmitter receptors on postsynaptic neurons 

    • Formation of new synapses between presynaptic and postsynaptic neurons

Neural Adaptations to practice

Practicing motor skills induces cortical, subcortical, and spinal adaptations that improve motor skills

Cortical regions

• Typically exhibit lower activity 

  • Reflects greater efficiency of neural processing

Subcortical regions

• Often exhibit greater activity 

  • Reflects recruitment of additional resources

Spinal regions

• Commonly exhibit lower activity

  • Reflects decreased reliance on hard-wired circuits that mediate stereotyped actions

Neural adaptations following BALANCE PRACTICE

• Practicing balance tasks induces cortical, subcortical, and spinal adaptations that lead to greater autonomic control of posture

Lower cortical activity

Reflects decreased use of voluntary postural control

Greater subcortical activity

Reflects increased use of autonomic postural control

Lower spinal activity

Reflects decreased use of reflexive postural control