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John Harris

Lecturer in Neurophysiology, Faculty of Science

Contact

  • workRoom C18 School of Veterinary Medicine and Science
    Sutton Bonington Campus
    Sutton Bonington
    Leicestershire
    LE12 5RD
    UK
  • work0115 951 6316
  • fax0115 951 6302

Research Summary

All previous work on the organisation and re-organisation of withdrawal reflexes has been based on the measurement of electrical signals rather than the actual movements made. Thus, the primary… read more

Selected Publications

Current Research

All previous work on the organisation and re-organisation of withdrawal reflexes has been based on the measurement of electrical signals rather than the actual movements made. Thus, the primary objective of the present studies is to quantify the movements generated in withdrawal reflexes, by measuring 3-dimensional position changes of a limb evoked by mechanical stimulation of selected parts of the same limb. Once the "normal" organisation of reflex movements has been mapped, it is proposed to examine how reflexes are altered by (i) acute noxious stimulation of strategically-selected parts of the foot; (ii) analgesic drugs, (iii) disruption of endogenous control systems; and (iv) acute and chronic inflammation. This is the first time that the stimulus site-dependence of the movements generated in response to cutaneous stimulation has been studied. Combining motion analysis (Codamotion®) with electrophysiology will provide a crucial link between behavioural and electrophysiological studies of pain, and will provide important data on the motor adaptations to arthritis.

Past Research

Opioids are important analgesics in animals and man but their effectiveness can be radically altered in some chronic pain states. Against inflammatory pain they are generally found to be more potent compared to use in acute pain, however for the treatment of pain following nerve injury (neuropathic pain), opioids can be completely ineffective. Research into the mode of action of opioids is therefore of major importance. A crucial site at which the inhibitory effect of opioids is mediated is the spinal cord (as evidenced by their effectiveness following epidural application), however opioids also have an action in the brain, where it is thought they cause disinhibition (i.e. an overall facilitation) of inhibitory pathways to the spinal cord thereby suppressing the transmission of nociceptive information. Thus one possible explaination for the reduction in efficacy of opioids in neuropathic states is the breakdown of opioid-activated descending inhibition to the spinal cord. Previous studies by our group have therefore looked further at the involvement of these pathways from the brain in determining the potency of opioids, and how their interaction might change in inflammatory and neuropathic conditions. These studies aid in the design of analgesic strategies for long-term pain states.

Future Research

My future plans are to use functional magnetic resonance imaging (fMRI) to look at spinal cord excitability in conditions of acute and chronic pain.

School of Biosciences

University of Nottingham
Sutton Bonington Campus
Loughborough, Leicestershire LE12 5RD

telephone: +44 (0)115 9516400
fax: +44 (0) 115 951 6020
email: biosciences-enquiries@nottingham.ac.uk