Fig. 3.

Sigma band energy variation (in dB) during scalp spindle intervals compared to control intervals for individual spindles. Each row corresponds to a different intracranial channel and each column to a single scalp spindle. The channels are sorted according to the p-value in a paired t-test comparing the sigma band energy in the spindle and control intervals. The white spaces correspond to channels of subjects with fewer than 50 marked scalp spindles. Channels show a large variability in sigma band energy increase at the time of different scalp spindles. More significant channels are more likely to exhibit an increase in the sigma band energy, but such increases are also seen occasionally on non-significant channels.