Somatosensory evoked fields after exercise induced pain

Abstract

The amount of research utilizing magnetoencephalography (MEG) has increased within the last few decades because of the development and better availability of equipment. With MEG, different areas of brain functionality can be studied in a variety of tasks and pathologies. Somatosensory evoked fields (SEF) are magnetic fields generated by tens of thousands of neurons firing in the primary somatosensory cortex. The purpose of this master’s thesis is to study the modulation of SEFs after exercise induced pain.

The study was carried out in Jyväskylä Centre for Interdisciplinary Brain Research (CIBR). The study subjects (N=18, male 10, female 8) were healthy and suitable for MEG measurements. Data was gathered in December 2015 and January 2016 in collaboration with another Master’s student. An international article will be published utilizing the data of the present measurement protocol. The study subjects’ SEFs were measured from the median nerve of the right arm before and after a 2 minute fatiguing static gripping task.

Two components were analyzed from the SEFs. The first component (N20) can be seen roughly 20 ms after stimulus onset. The second analyzed component (P40-60) was a later response to the stimulus, appearing at 40-60 ms after stimulus onset. The static gripping task had no statistically significant effect on the peak amplitudes of the N20 component (p=0,529) or the P40-60 component (p=0,160). The change in the ratio of N20 and P40-60 components was also analyzed, but no statistically significant difference was found (p=0,169).

With this study protocol, exercise induced pain does not have a statistically significant effect to somatosensory processing in the primary somatosensory cortex. Pain after fatiguing muscle activity seems not to be inhibitory or excitatory to somatosensory processing. Future studies in the subject area should have a larger study group and further develop the study protocol.