Video-electroencephalographic (EEG) recordings before and after 6-Hz corneal stimulation in mice.

(A) EEG traces obtained from frontal and occipital cortices, and hippocampal CA1 area before, during and after a corneal stimulation from one representative mouse. Pre-stimulus represents baseline activity. Black bar indicates stimulus artifact. In post-stimulation period, two major components are evident: ictal event followed by post-ictal depression characterized by flattening of basal activity (compare traces during post-ictal depression and baseline provided at higher magnification in insets). Small inset on the left shows electrodes position. (B) Mean power spectra obtained by fast Fourier transformation of traces recorded by epidural electrode in frontal cortex, during baseline (n = 6), ictal (n = 6), post-ictal (n = 6) and recovery (n = 5) phases. (C) Histogram on the left shows that power peak during ictal event is significantly greater that power peak during baseline, post-ictal and recovery phase (** = P<0.005; Mann-Whitney rank sum test). Histogram on the right shows that power peak during post-ictal depression is significantly lower than power peak during baseline and recovery (P<0.005; Mann-Whitney rank sum test). CA1: Cornu Ammonis 1 (depth electrode); Ref: reference electrode; RFC: right frontal cortex (epidural electrode); ROC: right occipital cortex (epidural electrode).