Attentional modulation of somatosensory steady-state in the human EEG

Giabbiconi, C.-M., and Müller, M. M.
Institut für Allgemeine Psychologie, University of Leipzig, Germany

Focusing attention to a specific location in the environment has been shown to improve perception of objects or events that are within the so-called ‘spotlight of attention’. The steady-state response (SSR) in the human EEG has been used in the visual and auditory modality in order to investigate attentional mechanisms in the human brain. As of today, little is known about the attentional modulation of the somatosensory steady-state evoked potentials (SSSEPs) and their underlying cortical mechanisms. We elicited somatosensory steady-state evoked potentials by mechanical vibratory stimulation applied to the second metacarpal of the left and right index finger (4.9 Newton) and subjects were instructed to selectively attend to one finger while ignoring the other. We showed a significant increase of SSSEP amplitude for attended stimuli for frequencies in the 20 Hz range. Further, we replicated this effect in a high density EEG experiment, allowing us to examine the topographical distribution of the attentional SSSEP modulation. The importance of this result for research on attention, in particular cross-modal integration and clinical research will be discussed.