Figure 3. ON and OFF-type hindbrain ELL pyramidal neurons display more phase invariance by decoding correlated activity from peripheral afferents.

(A) Schematic showing the different stages of processing in the electrosensory system. Recordings were made from ELL ON- (N = 22) and OFF-type (N = 9) pyramidal neurons. (B) Example responses of an ON-type (green) and an OFF-type neuron (magenta) to stimulus waveforms associated with the same electrosensory object. Shown are the stimulus waveforms, raster plots showing responses to 20 presentations of each stimulus, and trial-averaged time varying firing rates. Stimulus waveforms corresponding to '+ chirps' are shown above while those corresponding to '- chirps' are shown below. Note that excitatory responses of the ON-type neuron were mainly observed during + chirps while excitatory responses of the OFF-type neuron were found for - chirps. (C,D) Averaged time dependent firing rates for ON (C) and OFF (D) –type neurons in response to '+ chirps' (dark green) and '- chirps' (light green). (E) Tuning curves averaged from individual responses for ON- (green) and OFF (magenta) -type neurons. (F) Phase invariance scores computed from individual ON and OFF-type pyramidal neurons for all stimulus waveforms, same-type chirp combinations only ('++/- -'), and opposite-type chirp combinations only '+- chirps'. '*' indicates statistical significance at the p = 0.05 level using a one-way ANOVA.

DOI: http://dx.doi.org/10.7554/eLife.12993.010

Figure 3—figure supplement 1. Responses of ELL pyramidal ON and OFF type populations to chirp stimuli.

(A) Averaged responses of ON (green; N = 22) and OFF- (magenta; N = 9) type pyramidal neurons to '+ chirps' (top row) and '- chirps' (lower row). Note that '+ chirps' elicited increased response of ON-type units, while '- chirps' instead elicited increased response in OFF-type units. (B) Correlation coefficients for linear correlations of the ON- and OFF-type population responses for the chirps occurring at different phases in the beat cycle. Note that for all chirp waveforms the population responses were significantly negatively correlated (r<-0.45; p<<10–3 in all cases). (C) Plots of the distance between responses as a function of the distance between the corresponding stimulus waveforms for example ON-type (green) and OFF-type (magenta) ELL pyramidal cell.

DOI: http://dx.doi.org/10.7554/eLife.12993.012