Individual peak alpha frequency in touch – cognitive and methodological implications
Alexander Jones1, Jonathan Silas1; 1Middlesex University London
Oscillations in the alpha frequency range (8-12Hz), measured using electroencephalography (EEG), have been shown to have a functional role in cognition and attention in particular. For example, voluntarily shifting covert attention to one side of space leads to a decrease of alpha activity over the contralateral hemisphere. More recently, interest has turned to the notion that across individuals there is notable variance in the peak of the frequency, and these peaks are dependent on task demands or the participant’s “state”. Here we directly contrast four separate tasks commonly known to modulate alpha power, in a within subjects design. Using a somatosensory cue, participants (N=21) either oriented (1) endogenous or (2) exogenous attention to the right or left hand and response times were measured. In a passive task (3) participants received tactile stimuli at regular intervals to one hand only, akin to studies determining peak alpha desynchronization for subsequent brain stimulation. Finally, EEG was measured from participants whilst at rest (4) when no stimuli were presented. Results show a difference in lateralized alpha power depending on the task. Interestingly, we also observe differences in peak frequencies across tasks within the same individual. These findings have key implications in terms of understanding the functional role of alpha oscillations and how they vary across different states and individuals. Furthermore, recent advances in transcranial alternating current stimulation (tACS) have relied on ‘individualising’ EEG frequencies for subsequent stimulation. We suggest, that such frequency ‘individualisation’ or ‘localisation’ for the purposes of tACS, requires task-specific functional localisation.
Topic Area: ATTENTION: Other