Figure 1. Approach for chronic single unit recordings and optogenetic activation in mouse A1.

(A) Immunolabeling of PV neurons in A1 with co-localization of EYFP reporter in Pv-Cre:Ai32 transgenic mice. DAPI labels cell nuclei. Scale bar = 15 µm. (B) Spike raster plots illustrating that optogenetic activation of fast spiking (FS) PV+ units (black, top) inhibits regular spiking (RS) units (gray, bottom). Right, spike waveforms for the RS and FS units. Arrowheads denote spike peak and trough. Scale bars, 0.5 ms and 50 µV. (C) Scatter plot showing the bimodal distribution of peak-tough amplitude and timing differences across all RS (gray) and FS (black) units. (D) A random sub-sampling of spike waveforms recorded over 53 days from a single wire of a tetrode projected down into the first three principal components (PC). (E) Spike waveforms from the two units identified in (D) across all recording sessions, color-coded and superimposed chronologically. Waveforms for random units were selected at random from all simultaneously recorded units. (F) The variability in the actual unit waveforms, estimated as the sum of squared errors (SSE), is significantly less than randomly shuffled units (p<0.001, f(1)=814.73, mean ± SEM). (G) Experimental design.

DOI: http://dx.doi.org/10.7554/eLife.21452.002

Figure 1—figure supplement 1. Long-term tetrode recordings from isolated single units is feasible with RS neurons, but not FS neurons.

(A) As per Figure 1E, single unit spike waveforms across all recording sessions, are shown for a representative RS unit as well as two representative FS units. The RS unit waveform is consistent across the 7–8-week recording period, while the FS unit waveforms are lost after a few recording sessions. (B) Cumulative probability functions depict the number of consecutive recording sessions before each RS and FS unit was lost in noise-exposed and ouabain-treated mice. (C) For the analysis provided in the main text, we only analyzed units that were present in at least 75% of all recording sessions for a given mouse. None of the FS units we recorded met this criterion. Thus, we were unable to contrast changes in the FS neurons themselves with changes reported in the main text for RS neurons or PV-mediated inhibition.

DOI: http://dx.doi.org/10.7554/eLife.21452.003