The Oscillation Score: An Efficient Method for Estimating Oscillation Strength in Neuronal Activity.
We present a method that estimates the strength of neuronal oscillations at the cellular level, relying on autocorrelation histograms computed on spike trains. The method delivers a number, termed oscillation score, that estimates the degree to which a neuron is oscillating in a given frequency band. Moreover, it can also reliably identify the oscillation frequency and strength in the given band, independently of the oscillation in other frequency bands, and thus it can handle superimposed oscillations on multiple scales (theta, alpha, beta, gamma, etc.). The method is relatively simple and fast. It can cope with a low number of spikes, converging exponentially fast with the number of spikes, to a stable estimation of the oscillation strength. It thus lends itself to the analysis of spike-sorted single-unit activity from electrophysiological recordings. We show that the method performs well on experimental data recorded from cat visual cortex and also compares favorably to other methods. In addition, we provide a measure, termed confidence score, that determines the stability of the oscillation score estimate over trials.
Free source code for computing the oscillation score from spike times or auto-correlation histograms:
NOTE: Numerical results may slightly vary between the Matlab and C++ implementations due to small differeces when computing the Fast Fourier Transform.
Delphi source code as well as a Windows DLL library for computing the oscillation score are freely available for download on the webpage of Dr. Raul C. Muresan