Figure 6.
EPSP efficacy varies in time with LGN spike type. A, A set of 200 rasters for each category of LGN spike from an OFF magnocellular neuron (LGN spike, black dot; EPSP, red dot). Rasters were centered at t = 0 for the LGN tonic spikes and for the initial spikes in a short-ISI or burst spike train. B, LGN spike auto-correlograms (black) and LGN–EPSP cross-correlograms (red) computed from the entire dataset for this cell (tonic, n = 13,267; initial short-ISI, n = 3,560; initial burst, n = 1519). The correlograms were zeroed over the interval −1 < t < 1 ms for tonic spikes and −1 < t < 5 ms for short-ISI and burst spikes to avoid the large central peaks present by definition and were then smoothed with a 2-ms-wide Blackman filter. Bin size, 0.5 ms. Dotted lines, Mean firing rates. C, Population EPSP efficacy profiles for each category of spike, centered on t = 0 for a tonic LGN spike (left) or on the initial spike in a short-ISI or burst train (middle and right). For burst spikes, the efficacy was 0 by definition for 100 ms before the burst train. The number of short-ISI or burst spike trains was too small in seven cells to generate meaningful efficacy curves. Blue shading, One SD; red dotted line, mean efficacy.