Patterns of θ oscillations in marmoset hippocampus.

(A) Above shows a spectrogram highlighting the spectrotemporal dynamics of θ oscillations during locomotion. Below plots the corresponding raw voltage recording from an electrode within the hippocampus during recording. Blue shading reflects the occurrence of θ oscillations. (B) Normalized power spectral across all channels recorded with place-cell activity. Mean power spectra ± SEM is shown by the dashed black line and gray shading, respectively. Blue shading indicates the θ frequency range of 5 to 10 Hz. (C) Plots of the mean (dashed line) and lower and upper limits (light blue shading) of the θ oscillation for each channel recorded with a place cell (i.e., θ bandwidth). The channels have been resorted across all subjects/recordings according to the frequency at which peak θ power was identified. The mean peak across the population was 6.5 Hz. Differences between the number of HV (>20 cm/s; purple shading) versus LV (<20 cm/s, ≥0 cm/s; blue shading) locomotion are plotted for both (D) bout duration and (E) bout power. Neither metric was significantly modulated by locomotor speed when bouts were pooled across all recording sessions (p > 0.05, KS test). The underlying data can be found at https://doi.org/10.5061/dryad.kk63d49. HV, high velocity; LV, low velocity.