Spike parameters were analyzed from spontaneous spikes in whole-cell, voltage-follower mode recordings (current clamp, at I = 0; synaptic transmission was pharmacologically blocked).
No single spike parameters differed between control and depolarized neurons in pro-PKA conditions (Table S2), but there were significant negative correlations between voltage threshold and AIS length in both treatment groups.
Nevertheless, data (Kaphzan et al., 2011, Kaphzan et al., 2013, Kuba and Ohmori, 2009, Kuba et al., 2010) and models (Baalman et al., 2013, Kress et al., 2010, Kuba et al., 2006, Wang et al., 2011) predict that AIS shortening should also cause changes in single spike parameters.
We found that although control mice and non-tinnitus mice show similar non-tinnitus behavior, similar fusiform cell spontaneous firing rates (Li et al., 2013), similar levels of KCNQ2/3 channel activity (Li et al., 2013), and similar spike parameters (Supplementary file 1; 'Materials and methods'), non-tinnitus mice are biophysically distinct from control mice.
Each E and I cell is implemented as an exponential integrate and fire neuron and so its membrane potential approximates the dynamics of a real neuron, as opposed to models in which synaptic input directly updates a spike rate parameter.
On these spike trains parameters and response kernels are estimated.
Recorded spikes were isolated using the Plexon OfflineSorter software: multiple spike sorting parameters (e.g., principle component analysis, energy analysis) were used for the best isolation of the tetrode-recorded spike waveforms.
The first two principal components, as well as the peak height, valley value, FFT and total energy of spike waveform parameters were calculated for each channel, and units were identified and isolated in high-dimensional space through the use of an autoclustering method (KlustaKwik 1.5) [37].
The clusters were separated identically by k-means of the waveforms, and the distribution of the spike width parameters.
Similarly to the previous section, we use 100 sample spike trains per parameter set, with each spike train consisting of N = 1000 ISIs.
