Distinction of different fingers by the frequency of stimulus induced beta oscillations in the human EEG

Induced beta oscillations were studied in three normal subjects after mechanical stimulation of each fingertip of the right hand. For stimulation short tactile stimuli of 10 ms duration were presented at intervals of 4 s. The electroencephalogram was recorded with 60 closely spaced electrodes and sampled at 256 Hz. For each subject the reactive beta band was determined by comparing 1-s power spectra. The largest beta power increase was found in the range of 12-28 Hz on electrodes overlying the left-hand area. The Matching Pursuit algorithm was applied to single trials data and the frequency of single "atoms" determined. In one subject the little finger showed a significant higher frequency as compared to the thumb. The difference in frequency was in the order of 1 Hz.