Figure 6.
PCIST positively correlated with the depth of the stimulation site within the M2 cortex during wakefulness and ketamine anesthesia, but not with propofol or sevoflurane. A, left, Coronal cortical sections (Nissl staining) showing the location of the electrode for electrical stimulation in the right M2 cortex from one rat with the tip of the electrode positioned close to the cortical surface (top panel, superficial) and from another animal with the tip of the electrode deeper implanted in the cortex (bottom panel: deeper). Black arrowheads indicate the marks of one pole of the stimulating electrode. Right, Superimposition of mean ERPs from all recording electrodes in response to single pulse stimulation (1 ms, 50 μA; dashed line) from the same two rats shown on the left, during wakefulness (W) and propofol (P) and ketamine (K) anesthesia. One averaged ERP from the same channel (S1) is shown in bold to highlight differences across conditions. B, Values of PCIST (in time range: 0.08–0.6 s) from six rats and for all conditions are plotted against the corresponding distances of the stimulating electrode tips from the cortical surface and linearly fitted (coefficient of determination R2 and p value are reported if p < 0.05). Strong positive correlations were identified for wakefulness and ketamine conditions with similar slopes (45.35 and 46.30, respectively), but not for propofol and sevoflurane (S) anesthesia. See Extended Data Figure 6-1 for in depth examination of correlation of PCIST with stimulus location in wakefulness (examples of ERPs with sevoflurane are also shown). See Extended Data Figure 6-2 for correlations with stimulus location of number of principal components and state transitions, HF power and ITPC drop time, in all conditions. See Extended Data Figure 6-3 for in depth analysis across conditions, with only those rats with confirmed colocalization of stimulating electrodes in Layer II/III.