Figure 2.

Two types of taste neurons can be observed in BLA. A, Scatterplot showing the response properties of all BLA neurons that responded to taste administration with excitatory changes in firing rate. Each neuron's responses were averaged across tastes (x-axis, average response duration; y-axis, average response onset), such that there is one dot on the graph per neuron. Neurons that appear to cluster together are plotted in the same color. B, The results of a hierarchical cluster analysis on the same data, confirming that BLA taste-responsive neurons, color-coded to match A, come in two types. Note the high intracluster similarity (far-left branching) and low between-cluster similarity. C, Population histograms of the neurons in each cluster, color-coded to match A and B, showing that the responses of LD and SD neurons start at similar magnitudes but quickly diverge. The x-axis is time after delivery (the time of taste delivery is noted with a vertical line), and the y-axis is average firing rate in spikes per second. Error bars (here and in all other figures) are SEM. D, Plot showing, for LD and SD neurons, the average between-taste differences in response. The x-axis is time after delivery, and the y-axis is difference in spikes per second. SD responses to different tastes differ immediately, whereas LD responses to different tastes are similar early and then diverge. *p < 0.05, LD>SD; ^#p < 0.05, SD>LD.