Synchronization of Isolated Downstates (K-Complexes) May Be Caused by Cortically-Induced Disruption of Thalamic Spindling
Figure 12
Disruption of spindling in the human thalamus precedes the cortical KC.
KCs chosen on a single prefrontal bipolar SEEG channel located in Brodmann's area 10 are displayed as single trials (A, 50 randomly selected individual KCs) and, B, the average of all 229 KCs, band pass filtered to 0.1 to 5 Hz. C, Time frequency analysis (5–120 Hz) in the 1st (most medial) thalamic bipolar SEEG channel using the times of the frontal KCs in B, thresholded at p<0.01 (uncorrected) compared to the −1.5 to −0.5 second baseline. The blue arrow shows that there appears to be a drop in spindle power. D, The average absolute value of the Hilbert transform applied to the frontal KCs in B, band pass filtered for high gamma (60–120 Hz), is plotted in black. The grey box indicates the time period where high gamma drops significantly compared to baseline, outlined with a black box (−1.5 to −1 seconds, p<0.01, FDR corrected). The blue line indicates the average absolute value of the Hilbert transform applied to the 1st thalamic bipolar SEEG channel band pass filtered for spindling (12–16 Hz), using the times of the frontal KCs. The blue box indicates the time period where spindling drops significantly compared to baseline (p<0.01, FDR corrected). The drop in thalamic spindling (blue box) occurs prior to the drop in cortical high gamma (grey box). E& F, The same analysis as outlined in D is applied to the 2nd thalamic bipolar channel (E) and the 3rd thalamic bipolar channel (F). The cortical data are the same in all three subplots; the thalamic spindling amplitude scales are individualized for each thalamic bipolar contact in D–F. For all three thalamic bipolar channels, thalamic spindling drops significantly (blue box) prior to the significant cortical high gamma drop (grey box).