Figure 5.

Spike-LFP relationships during transient high-gamma epochs. Figure shows two examples (one in each column; from different rats) of joint LFP and single-neuron recordings during maze task performance. A) Ventral striatal LFP oscillations surrounding arrival at reward ports; wavelet scalograms were calculated as in Fig. 4. but for rewarded trials only (n=111, 68). B) Spike rasters and histograms for one neuron from each of the same tetrodes as the LFP recording used in A. Left neuron is a presumed striatal FSI (same neuron as Figure 2Aiii); Right neuron had a complex double-peaked waveform and was unclassified. Note that the FSI at left does not substantially change its firing rate during the increase in LFP high-gamma power Colored bars above rasters indicate analysis periods used in C,D. C) Histograms of inter-spike intervals (ISIs; 1ms bins) for the two neurons in B. ISIs were calculated during four 0.7s periods relative to arrivals at baited reward ports, and color-coded (blue = −2.3 to −1.6s, green = −1.0 to −0.3s, red = +0.3s to +1.0s, black = 1.6s to 2.3s). The FSI at left shows only subtle changes in the ISI distribution. Neuron at right commonly fires at ~20ms or ~40ms intervals (corresponding to ~50Hz entrainment) but shows a dramatic, transient shift to shorter (~2ms and ~12ms) intervals, consistent with firing spike doublets at ~80Hz. D) Spike-field coherence plots. SFC is calculated during the same intervals as in C. Both neurons show an transient behavior-linked increase in high-gamma coherence to LFP.