Effective dimensionality of neuronal population activity in hippocampus correlates with behavior

We studied the population activity of hippocampal neurons in mice during novel arena exploration. To quantify the partial synchronization of neuronal activity, we calculated the effective dimensionality of a multidimensional time series of neuronal activity obtained using in vivo using calcium imaging. The effective dimensionality was calculated from the spectra of correlation matrices subjected to the consistent bias correction procedure. Applying this algorithm to mouse neural activity data, we found that the effective activity dimensionality of neuronal populations significantly increased during periods of animal stops. We attribute this finding to the presence of functional ensembles of neurons associated with movements, whose synchronised activity was disrupted during stops.