Cutaneous Experimental Pain Research Laboratory

Aim

Head of Laboratory Carsten Dahl Mørch, Associate Professor  CDahl

The aim of the Experimental Cutaneous Pain Research laboratory is to develop, refine and apply techniques for induction and assessment of cutaneous pain. This includes acute pain induced by thermal, mechanical, chemical, or electrical stimulators. It also includes models of persistent cutaneous pain, hyperalgesia, allodynia and associated vascular responses. One of the main research topics is the nociceptive withdrawal reflex which is investigated in detail for understanding reflex pathways, reflex modulation, and as a tool for probing spinal nociception.

Assessment of the organisation of nociceptive withdrawal reflexes in the lower limb involve several stimulation sites on the sole of the foot. Typical reflex size distribution for the tibialis anterior muscle is depicted on the right.

Main Research Areas

1. Cutaneous stimulators and psychophysics
   New stimulators are constantly being developed. Recent stimulators include a cold stimulator capable of maintaining skin temperatures down to -10°C. Heat stimulation is achieved by custom designed radiant heat stimulators where temperature controlled uniform skin heating is an important feature. Advanced psychophysical methods are used for assessing the nature of cutanous nociception with focus on spatio-temporal perception.
2. Models of cutaneous hyperalgesia and Long Term Potentiation (LTP)
   New models are developed and sensory characteristics of existing models are evaluated. Both sensory and vascular measures are assessed by state-of-the art cutaneous stimulators and imaging techniques for evaluating peripheral and central mechanisms.
3. Electrical stimulation of nociceptors
   Standard electrical stimulation techniques activate thick myelinated nerve fibres prior to activation of nociceptors. At this lab, research into methods for selective activation of nociceptors is based on theoretical and experimental methods which focus on the shape of the stimulation pulse and on electrode design.
4. Sensory integration in the nociceptive system
   Integration of concurrent nociceptive activity and repetitive nociceptive activity is reflected in the size of the nociceptive reflex. Hence, a gradual build up in reflex size is seen when a train of painful stimuli is presented with a stimulation frequency above 0.5 Hz. Moreover, the reflex is used to probe the spinal processing of cross-modality afferent activity.
5. The nociceptive withdrawal reflex: Probing spinal nociception
   The spinal organization of withdrawal reflexes receives substantial attention in the lab. Methods for quantifying the reflex receptive field (RRF) are constantly in focus. The RRF technique is utilized to study spinal nociceptive processing in models of central sensitization and in patients. The influence of descending control is evaluated, e.g. by studying reflexes in spinal cord injured volunteers.

Cutaneous blood flow (right) is measured using laser Doppler flowmetry (left). These vascular changes are compared to sensory changes around the capsaicin injection site (middle figure, notice the redning of the skin). Sensory changes typically involve mechanical and thermal modalities.

Key Collaborators

• Nanna Finnerup, Astrid Terkelsen, and Troels Staehelin Jensen, Danish Pain Research Center, Aarhus University Hospital, Aarhus, Denmark.
• Michele Curatolo, Division of Pain Therapy, Department of Anesthesiology, University Hospital of Bern, Inselspital, Switzerland.
• Jörg Trojan and Dieter Kleinböhl, University of Mannheim, Otto Selz Institute for Psychology and Educational Science, Laboratory for Clinical Psychophysiology, Germany
• Robert C. Coghill, Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
• Barry Sessle, Faculty of Dentistry, University of Toronto, Ontario, Canada
• Claudia Spadavecchia and Alessandra Bergadano, Department of Clinical Veterinary Medicine, Anaesthesiology Division, Vetsuisse-Faculty, University of Berne, Switzerland.
• Dorit Pud and David Yarnitsky, Faculty of Social Welfare and Health Studies, University of Haifa, Haifa, Israel
• Peter Andersen and Ole Bjarlin Jensen, Risoe National Laboratory, Optics and Plasma Research Department
• Oliver Wilder-Smith, Pain Centre, Department of Anaesthesiology, University Medical Centre St. Radboud, Nijmegen, The Netherlands

Further reading available here.