We used a generalized linear model with a logistic link function to determine whether gamma was predictive of the presence

of an SWR. Either the average gamma power across CA1 or CA3 tetrodes or the gamma coherence between the CA1 and CA3 tetrodes with the maximum number of cells was computed across the entire behavioral session in 200 ms temporal bins. For each bin we also determined whether or not an SWR was observed. Gamma power or coherence was said to predict the occurrence of an SWR for behavioral sessions with significant coefficients for the gamma regression Neratinib clinical trial term. To illustrate the relationship between either gamma power or coherence and the occurrence of an SWR, we binned gamma power or coherence and then computed the proportion of 200 ms bins that had an SWR. SWR triggered coherence was computed for all CA3-CA1 tetrode pairs. To quantify

the magnitude of gamma coherence during SWRs, we computed the absolute value of the average coherence in the gamma band across all CA3-CA1 tetrode pairs. To quantify gamma phase locking during SWRs, the phase of coherence for the gamma band was averaged across all CA3-CA1 tetrode pairs for each SWR. Thus, each SWR contributed a single value for each 100 ms temporal bin relative to SWR detection. We combined values across SWRs to obtain a distribution http://www.selleckchem.com/products/pd-0332991-palbociclib-isethionate.html of gamma phase offsets in each bin. The angular variance of this distribution was taken as a measure of phase locking for each session. Putative interneurons were identified on the basis of spike width and average firing rate (Ranck, 1973; Fox and Ranck, 1981; Frank et al., 2000) and were excluded from all analyses. Gamma phase was measured on the CA3 tetrode with the largest number of isolated cells by band pass filtering (20–50 Hz) the local Florfenicol field potential, performing the Hilbert transform on the filtered

signal, and extracting the phase component. Spikes that occurred during an SWR were identified and the gamma phase at the time of the spike was assigned. Spikes were pooled across neurons recorded in each region. The depth of modulation was defined as the difference between the peak and the trough of the spiking distribution divided by the sum of the peak and the trough of the spiking distribution. As in our previous work (Karlsson and Frank, 2009), for every pair of place fields we measured the linear distance between the place field peaks as the shortest path between the peak firing rate locations. We also measured the absolute value of both the time and gamma phase from each reference spike for one cell to all spikes from the other cell. For this analysis, gamma phase was measured on the CA3 tetrode with the most cells. Note that the pairs of spikes were often compared across multiple cycles of gamma. In the large majority of cases the Hilbert Transform yielded a continuous estimate of phase throughout the entire SWR.