Cortical Neuroplasticity by Muscle Pain of Pain-induced Plasticity

Cortical Neuroplasticity by Muscle Pain and Non-invasive Modulation of Pain-induced Plasticity

The purpose of this study is to investigate the sensory-motor cortical excitability response to delayed onset muscle soreness (DOMS) on Extensor Carpi Radialis (ECR) muscle during muscle hyperalgesia provoked by nerve growth factor (NGF).

The purpose of this study is to assess changes in sensory-motor cortical excitability during experimental muscle hyperalgesia across several days provoked by injections of nerve growth factor (NGF) into the Extensor Carpi Radialis (ECR) muscle and delayed onset muscle soreness (DOMS) of the ECR muscle.

It was hypothesized that muscle hyperalgesia across several days would result in:

i) Increased sensory cortical excitability, based on somatosensory evoked potentials by means of electrical stimulation of the radial nerve, (increase of central-parietal evoked-potential P45 and decrease of frontal evoked-potential N30); ii) Increased corticomotor excitability of a ECR (increase map volume and number of active sites), assessed as motor evoked potentials induced by transcranial magnetic stimulation in primary motor cortex (M1); iii) Reduction of alpha oscillation based on nociceptive stimulus-evoked suppression of alpha activity in sensory regions (recording electrodes on contra-lateral parietal area);

Inclusion Criteria:

• Healthy men and women
• Speak and understand English.

Exclusion Criteria:Pregnancy

• Drug addiction defined as the use of cannabis, opioids or other drugs
• Previous neurologic, musculoskeletal or mental illnesses
• Lack of ability to cooperate
• History of chronic pain or current acute pain
• Previous experience with rTMS
• Contraindications to rTMS application (history of epilepsy, metal in the head or jaw etc.).
• Failure to pass the "TASS questionnaire" (TASS = Transcranial Magnetic Stimulation Adult Safety Screen)