Skip to main content
. Author manuscript; available in PMC: 2018 Feb 1.
Published in final edited form as: Hear Res. 2016 Nov 9;344:13–23. doi: 10.1016/j.heares.2016.10.017

Figure 2.

Figure 2

5-HT has heterogeneous effects on evoked and spontaneous spiking of DCN neurons. (A) Representative example in which 5-HT application increased the spiking rate. The first three panels show PSTHs of the response before (left), during (middle), and following (right) the delivery of 5-HT. The bars below each PSTH mark the duration of the 25 kHz CF tone in the recording window. The last panel represents the spiking rate at time points over the course of the recording protocol, with the time course of 5-HT application depicted as a bar below the data points. Error bars represent the standard deviation of spiking to 100 presentations of the stimulus at each time point. (B, C) Example neurons that exhibited a decrease (B) and no change (C) in spiking during 5-HT application in response to respective 36 and 8 kHz CF tones. All tones had durations of 50 ms and were presented 10 dB above threshold. The colored symbols in the far right panels correspond to the middle PSTHs that represent the respective increase, decrease, and no change in response during 5-HT application. The corresponding colors in figures 3–5 also represent data from these example neurons. (D) Normalized change in evoked spiking for the sample of neurons was determined by dividing the mean spiking rate at the maximal 5-HT effect by the control rate prior to 5-HT application. Changes greater than 1.0 represent increases in spiking and changes less than 1.0 represent decreases. Changes greater than 0.1 in either direction were statistically significant (black bars; paired student's t test, α = 0.05), while changes less than 0.1 (white bars) could not be attributed to an effect of 5-HT. The majority of neurons (13/23) responded to 5-HT application with a significant increase in evoked spiking rate. (E) Normalized change in spontaneous versus evoked spiking rate during 5-HT application. The significant positive correlation of normalized responses (Pearson r = 0.65, p < 0.0001) indicates that 5-HT affected spontaneous and evoked spiking similarly.