Figure 3.

LD neurons produce time-varying taste responses with dynamics similar to those of GC. A, The top halves of each panel are the spiking activity of a representative LD neuron in response to each of the four tastes. Each row is a single trial, and each hash mark is an action potential; the x-axis is time, with 0 being the moment of taste delivery (marked with a vertical line). These plots are summarized below in PSTHs, which show the firing rate (in spikes per second) of the neuron in response to the tastes. Shaded areas indicate periods of firing significantly higher than the prestimulus rate. Note that there is an initial excitatory response to each taste but that the quinine and citric acid responses return quickly to baseline; the sucrose and NaCl responses remain high throughout the first second of the response, and the sucrose response remains high even after the NaCl response has declined. B, Plot showing the percentage of LD neurons (y-axis) that responded to one (blue line), two to three (red line), or all four (green line) tastes in each 250 ms bin of poststimulus time (x-axis). Each category peaks during a distinct epoch of time (neurons are most likely to respond to all 4 tastes early, to 2–3 tastes later, and to 1 taste later still).