Article Figures & Data
Figures
- Figure 1.
Theta phase modulates broadband high-frequency oscillations >100 Hz in the hippocampus, which correspond to spiking activity. A, Comodulation map. Warm colors denote presence of phase–amplitude coupling (see Materials and Methods and Tort et al., 2010b for details). B, Power spectral density in dB scale. Notice theta peak and absence of power peaks above 100 Hz. Inset shows power of fast oscillations in absolute scale (mV2/Hz). C, Multiunit activity as a function of SLHFO phase. D, Left, mean SLHFO amplitude (top) and multiunit activity (bottom) as a function of theta phase. Right, Normalized SLHFO and multiunit activity versus theta phase (0, minimal activity; 1, maximal activity). E, LFP averages triggered by SLHFO peaks (top) and spike times (bottom). Dashed line represents trigger time. The results shown in this figure were obtained from a representative LFP recorded from CA1 stratum pyramidale in a freely behaving rat during active waking.
- Figure 2.
Theta phase modulates genuine high-frequency oscillations >100 Hz in the hippocampus. A, Comodulation map. B, Power spectral density in dB scale. Notice theta peak and a power peak ∼140 Hz. Inset shows power of fast oscillations in absolute scale (mV2/Hz). C, Multiunit activity as a function of HFO phase. D, Left, Mean HFO amplitude (top) and multiunit activity (bottom) as a function of theta phase. Right, Normalized HFO and multiunit activity vs theta phase. E, LFP averages triggered by HFO peaks (top) and spike times (bottom). The results shown in this figure were obtained from a representative LFP recorded from CA1 stratum oriens-alveus in a freely behaving rat during active waking.
- Figure 3.
Theta phase can simultaneously modulate genuine and spurious high-frequency oscillations. A, Top, Power spectral density (in mV2/Hz). Bottom, Comodulation map. B, LFP averages triggered by the peaks of HFO (top) and SLHFO (middle), and by spike times (bottom). C, Left, Mean HFO amplitude (top), SLHFO amplitude (middle), and multiunit activity (bottom) as a function of theta phase. Right, Normalized HFO, SLHFO, and multiunit activity versus theta phase. The results in A–C were obtained from a representative LFP recorded near CA1 stratum pyramidale in a freely behaving rat during active waking. D, First column, representative sharp wave ripple event recorded from a 16-site probe (100 μm spacing); second and third columns, LFP averages triggered by the peaks of HFO (reference, site 1) and SLHFO (reference, site 7); fourth and fifth columns, averaged HFO- and SLHFO-filtered LFPs (same trigger as before); the color plots show the associated CSD maps; sixth column, comodulation maps for a recording site above (top) and (bottom) at the pyramidal layer. Notice prominent theta-HFO and theta-SLHFO coupling, respectively.
- Figure 4.
Group results. A, Mean normalized HFO, SLHFO, and multiunit activity as a function of theta phase (pyramidal layer reference). Theta peaks and troughs correspond to 180° and 360°, respectively (top sinusoid). These averages were computed from the pool of all electrodes exhibiting theta-HFO (n = 129) or theta-SLHFO (n = 182) coupling, as assessed by visual inspection of comodulation maps, across rats and behavioral sessions. Multiunit activity was obtained from multisite shanks placed at the pyramidal layer using each electrode contact as reference. Dashed lines denote the mean ± 1 SD. B, Mean theta phase of peak activity; *p < 0.0001 (Watson-Williams test). Error bars denote 99% confidence intervals.
