Fig. 4: Spike output of single granule cells in vivo.

a Representative recordings of the same cell as in Fig. 3a; simultaneous field potential recordings from S1 (top) and whole-cell current clamp recordings from a granule cell (lower); 20 traces are overlaid. The averaged traces are in red. Detected spikes are shown in raster plots (middle) and time histograms (bottom). Green and brown bars indicate the early and late phases, respectively. The trials under control (left) and light (right) conditions were interleaved. b Numbers of evoked spikes plotted against the native resting potentials (filled circles, n = 16). In a subset of cells that had hyperpolarized native resting potentials (<−65 mV), a steady depolarizing current was applied to facilitate firing (open circles, n = 9). The spike numbers were corrected for baseline spontaneous firing by subtraction in this and the following panels. c Numbers of evoked spikes in the early and the late phases were compared in 16 cells, including three cells that lacked voltage clamp recordings. Error bars indicate SEMs (trial-by-trial fluctuation). The arrow points to the cell recorded in a. d Numbers of evoked spikes in the early phase (left) and late phase (right) were plotted against the numbers of EPSCs during the same time periods. Individual cells (n = 13) are plotted as different marks common in d and e. e Left, averaged traces of all 16 granule cells in current clamp mode. Black, control; blue, photoinhibition of S1. Right, depolarization at 20 ms after the onset of stimulation is plotted against the number of EPSCs in the early phase. f Evoked spike numbers were compared for the early phase (left) and the late phase (right) (n = 16). Means ± SEMs are presented as black lines and bars, respectively.