EP 110. Phase-locking as a neurophysiological marker of movement execution in young and elderly subjects

• Published in: Clinical neurophysiology Vol. 127; no. 9; p. e287
• Main Authors: Popovych, S., Rosjat, N., Liu, L., Yeldesbay, A., Toth, T., Wang, B., Abdollahi, R., Viswanathan, S., Grefkes, C., Fink, G., Daun-Gruhn, S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2016
• Subjects: Neurology
• DOI: 10.1016/j.clinph.2016.05.153
• ISSN: 1388-2457

Motor actions are generated by complex interactions of various brain regions. The same brain regions can build various functional networks depending on the action. Identifying the neural signals that encode an action’s component (selection, preparation, execution) remains a difficult task. In the current study, EEG data were recorded continuously from 18 young (22–35years) and 16 elderly (60–71years) right-handed healthy subjects as they performed a simple motor task. The task required participants to execute a left or right index finger tapping triggered by a visual cue or by an uncued voluntary choice. We found that voluntary and visually triggered movements exhibit significant phase locking in the delta-theta frequency band (2–7Hz) around movement onset both in young and old subjects. However, significant differences in movement and processing time between the two groups of subjects were observed as well. Moreover, there was a negative correlation between the movement time and the maximal value of the phase-locking index (PLI) in young subjects. This indicates that the aforementioned changes in behavioral performance result from a decrease of PLI in the respective motor regions. In summary, we suggest that this enhanced intra-regional synchrony, which seems to be impaired in the elderly, helps the simultaneously active pathways of distinct cortical networks that initiate voluntary and stimulus-triggered movements, converge to a common motor output and activate the appropriate muscles to perform the movement. This mechanism may thus be regarded as a prototype for organizing more complex motor activities.