Synchronization of Isolated Downstates (K-Complexes) May Be Caused by Cortically-Induced Disruption of Thalamic Spindling
Figure 7
Evoking KCs by directly versus indirectly depolarizing RE.
A, KCs are evoked by directly depolarizing all RE neurons for 350 ms at 85.8pA. B, KCs are evoked by stimulating 6 PY neurons, indicated by the red arrow, for 200 ms at 15pA. In A & B, the membrane potential of individual neurons (Vm), the average membrane potential (Avg Vm), the spiking of a single cell, and the average spiking rate (Avg Spikes/Sec) are graphed for each population. The membrane potential color scales are the same for both panels for each cell population. The number of the individual cell graphed is also the same between panels. The length of the RE depolarization is outlined by the orange box and the length of the stimulation of the 6 PY neurons is outlined by the black box. In both cases, the KC was quantified by a drop in the PY membrane potential and the spiking in cell populations (blue asterisks and “KC”). There was a marked increase in the membrane potential of the stimulated 6 PY neurons projecting to all RE neurons (yellow asterisk). In both cases, RE membrane potential was depolarized for the duration of RE current injection or PY stimulation (purple asterisks), but this did not correspond to an increase in RE spiking (orange asterisks). Like the spontaneous KC (Figures 4 & 5), a drop in the TC and RE spindling occurred at the same time as the evoked KC (red asterisks) in both cases.