RTG 2175 Perception in Context and its neural Basis
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New TP Ruscheweyh/Deubel

Modulation of central sensitization in pain pathways by sensory and cognitive-emotional processes in humans

 

Supervisors:
PD Dr. R. Ruscheweyh, Department of Neurology, Ludwig-Maximilians University Munich and
Prof. Dr. H. Deubel, Department of Psychology, Ludwig-Maximilians University Munich

Ruscheweyh

Background and Goals:
Sensitization of central nociceptive (pain) pathways, also called “central sensitization”, is an important mechanism in the development and maintenance of chronic pain and can be induced by acute painful events.
It has been hypothesized that the context (e.g. the attentional and emotional state) present in the moment of an acute pain event can influence the development of central sensitization at the spinal level, e.g. by modulating the activity of descending pain inhibitory systems, and thereby impact the development of chronic pain (see figure). In the first part of the project, the effect of cognitive-emotional context on the development of central sensitization will be examined in a human experimental pain model.
In addition, at the cortical level, central sensitization leads to shrinking of somatosensory representation areas, as it has been demonstrated e.g. in phantom pain and in complex regional pain syndrome. Clinical pain and local cortical shrinking both can be partially reversed by sensory discrimination training, suggesting a tight multisensory interaction between tactile and nociceptive information. However, it is an open question if changes in sensory cortical representation alone lead to changes in pain perception and affect the induction of central sensitization. Therefore, in the second part of the project, the effect of a sensory (tactile) discrimination training on acute pain and central sensitization in the same human experimental pain model will be investigated.

Methodology and Work Program:
Capsaicin, the active ingredient of hot chili peppers, induced a burning pain sensation by activating TRPV1 receptors on nociceptive nerve fibres. In the human capsaicin model, application of capsaicin to the skin (via subcutaneous injection or patch) induces both, acute burning pain within the application area (acute nociception), and increased sensitivity to mechanical stimuli in a larger surrounding area. The latter phenomenon is termed “secondary hyperalgesia” and is believed to reflect central sensitization.
Part 1: The PhD student will use the capsaicin model on the forearm of healthy subjects to assess both acute nociception and central nociceptive sensitization. During the acute pain phase, attention (distraction from pain, pain catastrophizing) or mood (positive or negative emotions) will be modified by specific psychological interventions to determine if the attentional-emotional context plays a role in the development of central sensitization.
Part 2: In a second part of the project, sensory discrimination training using a 3x3 electrode array will be performed on the forearm. Subjects will learn to locate the stimulating electrode within the array and to detect the presence or absence of a short delay between stimulations of different electrodes. Sensory and nociceptive two-point discrimination thresholds will be measured to estimate the effect of the discrimination training on the sensory and nociceptive cortical representation. Then, the capsaicin model will be used on the site where discrimination training was performed, to determine if and in which direction an expansion of the cortical representation by sensory discrimination training affects acute nociception and/or the development of central sensitization.

If you are interested in this position, you should:

  • Have a genuine interest in the processes involved in acute and chronic pain perception, underlying neuronal systems, and their modulation by psychological and sensory processes.
  • Like to work with human subjects.
  • Be ready to perform preliminary work in order to establish and modify experimental procedures as needed.
  • Be able to work independently after the initial training. However, regular meetings and supervision of the experimental progress, data analysis and statistics are granted.
  • Be meticulous in the preparation and performance of the experiments and documentation of the results.
  • Have successfully completed the GSN-LMU’s selection procedure (for further information about the application, please click here)

More information:
The 3-year PhD position starts in October 2017 or latest in January 2018. It is part of a dedicated doctoral research training group (RTG 2175) at the Graduate School of Systemic Neurosciences of LMU Munich.
For more information, please contact: ruth.ruscheweyh@med.uni-muenchen.de