Neurophysiology Laboratory

Research Focus: Neural Control of Human Movement

The Neurophysiology Laboratory focusses on identifying how the nervous system controls human movement. Within this broad area of investigation, research is divided into two main categories:

  1. How sensory feedback contributes to movement control, including
  2. The role of reflexes in neural control of movements such as walking and grasping
  3. The importance of feedback from sensory receptors in the skin
  4. How intrinsic properties of neurons within the spinal cord play a role in helping to shape motor output, including
  5. The extent to which such intrinsic neuronal properties contribute to normal voluntary contractions and “abnormal” contractions such as those during muscle cramps, spasms and spasticity.
  6. Whether activating these spinal neurons may be useful clinically for functional electrical stimulation (FES) of muscle to help restore movement and overcome the muscle wasting that results from disuse.
  • Current findings show that:
  • when electrical stimulation is applied over human muscle, large contractions develop which are not due to the direct activation of the muscle beneath the stimulating electrodes.
  • They result from the “reflex” activation of neurons within the spinal cord, probably involving plateau potentials in the spinal neurons.
  • This suggests that human spinal neurons may play a very active role in helping to shape motor output.

Equipment:

  • 16 amplifiers for bioelectric signals (to record muscle and brain activity)
  • Grass S-88 stimulator with constant current and stimulus isolation units (to stimulate nerve and muscle)
  • Bicycle ergometer and custom made arm cycle ergometer (to study rhythmic movements of the legs and arms)
  • Treadmill (to study human walking)
  • Cybex 340 (to study isolated contractions of different muscle groups)
  • Penny and Giles goiniometer system (to record movements about different joints)
  • Custom written data collection (Labview) and analysis (Matlab) packages

Techniques:

  • EMG recording using surface and intramuscular electrodes (recording the activity of human muscle)
  • Human reflex studies including H-reflexes, stretch reflexes, tendon-tap and cutaneous reflexes
  • Muscle stimulation for functional electrical stimulation (to improve techniques for restoring movement for persons with stroke or spinal cord injury)
  • Somatosensory evoked potentials (recording brain activity in response to stimulation of sensory receptors in the arms and legs)
  • Motor evoked potentials using transcranial magnetic stimulation (recording responses in arm and leg muscles from stimulation of the brain)
  • Human microneurography (recording the activity of single nerve fibres in humans)
  • Psychophysical studies (to identify mechanisms involved in the perception of human movement; kinesthesia/proprioception)

Researcher: David F. Collins (link to A-Z faculty listing and research interests.)

Representative publications

Brooke, J.D., Cheng, J., Collins, D.F., McIlroy, W.E., Misiaszek, J.E., and Staines, W.R. (1997) Sensori-sensory afferent conditioning with leg movement: Gain control in spinal reflex and ascending paths. Prog.Neurobiol. 51(4):393-421.

Collins, D.F., Cameron, T., Gillard, D.M. and Prochazka, A. (1998) Muscular sense is attenuated when humans move. J.Physiol. 508.2: 635-643.

Collins, D.F. Knight, B. and Prochazka, A. (1999) Contact-evoked changes in EMG activity during human grasp. J.Neurophysiol. 81(5): 2215-2225.

Mushahwar, V.K., Collins, D.F. and Prochazka, A. (2000) Spinal cord microstimulation for the control of movement in chronically implanted cats. Exp.Neurol. 163: 422-429.

Collins, D.F., Refshauge, K.M. and Gandevia, S.C. (2000) Sensory integration in the perception of movements at the human metacarpophalangeal joint. J.Physiol. 529: 505-515.

Collins, D.F., Burke, D. and Gandevia, S.C. (2001) Large involuntary forces consistent with plateau-like behavior of human motoneurons. J.Neurosci. 21: 4059-4065.

Zehr, E.P., Chua, R., and Collins, D.F. (2001) Human interlimb reflexes evoked by electrical stimulation of cutaneous nerves innervating the hand and foot. Exp. Brain Res. 140: 495-504.

Collins, D.F., Burke, D. and Gandevia, S.C. (2002) Sustained contractions produced by plateau-like behaviour in human motoneurones. J.Physiol. 538: 289-301.

Stuart, M., Butler, J.E., Collins, D.F., Taylor, J.L., Gandevia, S.C. (2002) The history of contraction of the wrist flexors can change cortical excitability. (Rapid Report) J.Physiol. 545.3: 731 737.

Zehr, E.P. Collins, D.F., Frigon, A, and Hoogenboom, N. (2003) Neural control of rhythmic human arm movement: phase and task dependence of Hoffman reflexes. J.Neurophysiol. 89(1): 12-21.