FIG. 3.

Illustration of spatiotemporal pattern of the FA response in cortex after focal stimulation of VPM with 2 mM l-glutamate. A: expanded view of a baseline fluorescence imaging demonstrating the borders (dotted lines) of S1-trunk area (S1-Tr), S1BF, and S2, based on the presence of barrels in S1BF. Scale bar = 1 mm. B: Δf/f image of FA activation in S1BF after thalamic stimulation taken at 3.0 s after stimulus onset. C: Δf/f image of FA activation in S1BF after thalamic stimulation taken at 5.5 s after stimulus onset. D: time courses of activation in an ROI over the S1BF (purple), S1-Tr (green), and S2 (red) using a 1-s-long window for moving average. E: temporal phase of responses, illustrating phase lag of about 2 s in S1-Tr and S2 part of the cortex, and a relatively sharp demarcation of the S1BF/S2 border based on phase differences. See methods for details regarding phase analysis; only pixels with response amplitude >1% above baseline are shown. Pseudocolor scale bar represents phase lag in seconds. Horizontal scale bar = 1 mm. F: plot of percentage of the maximum number of pixels activated in a 30-pixel box scrolled along the diagonal line shown in E, for pixels with a lag of <4.5 s (purple) and lag >4.5 s (red). Overlaid in black is a high-pass filtered plot of pixel intensity of baseline fluorescence image, demonstrating regularity over the first 0.5 mm, corresponding to the barrel field, then transitioning to nonperiodic signal in S2 for both figures. G: time course of activation at the thalamic stimulation site (blue) and in a series of 40 pixels taken from a ring surrounding the thalamic stimulation site (green), normalized to the peak from the stimulation site. Inset shows areas in the center of the stimulus site (blue) and surrounding the site (green) from which pixels were derived for this analysis. l-Glutamate was applied through a picospritzer with pressure pulses (1 psi) 8 ms in duration, applied at 20 pulses/s, with 1-s train duration, with 14-s intertrain interval. Scale bar = 1 mm.