Fig. 6.

A: time series of voltage-sensitive dye (VSD) images during and after focal electrical stimulation in a parasagittal slice, to illustrate the development of the “patchy” or discontinuous distribution of activity along the rostrocaudal axis. Time points shown at left of each image are relative to the onset of the 30-ms stimulus train (Stim.; indicated by the red vertical bar). Note that the time intervals between the images are not equal throughout the series. Circle on each image marks the stimulus position. Dashed lines mark approximate position of the laminae I–II borders. Dorsal direction is at top. B: plot of time course of activity for the same stimulus trial shown in A. Time is represented on the y-axis (the dorsoventral axis is not represented in this plot). Activity is shown for a single rostrocaudally oriented line drawn approximately parallel to the laminar borders through the zone of peak activity (black line in top image). Arrowhead marks the rostrocaudal position of the stimulus. Distance calibration is same as in A. Stimulus intensity is 36 µA, which is considerably higher than the intensities used for the experiments illustrated in transverse slices (Figs. 1–4). All VSD images, ×10 objective.