Bimodal RMS distributions for the objective detection of theta (θ) and gamma (γ) brain oscillations during long-term continuous LFP recordings in mice.

Abstract In the rodent’s brain the theta (5-12 Hz) and gamma (30-120 Hz) oscillations can be readily detected in local field potential (LFP) recordings, but there is no universal consensus about an objective threshold for their detection. We FIR-filtered the long-term local field potential (LFP) recordings for theta and gamma oscillations. The RMS (root mean square) values of 8 s epochs in 0.5-4 s steps (using corresponding overlaps) were obtained from the filtered recordings. For both theta and gamma oscillations, the histograms showed a bimodal distribution well fitted by two Gaussians. The point of intersection between the two distributions proved to be the most reliable for separating the RMS values belonging to the two Gaussians.