In vivo characterization of neurophysiological diversity in the lateral supramammillary nucleus during hippocampal sharp-wave ripples of adult rats.

•Extra-hippocampal regions might participate in the expression of sharp-wave ripples (SPW-Rs).•We found two neuronal populations in the lSuM: SPW-R-active (increased firing during SPW-Rs), and SPW-R-unchanged neurons.•lSuM SPW-R-active neurons increased their firing prior to SPW-Rs peak power and hippocampal excitatory neurons.•lSuM SPW-R-active neurons showed a higher firing during theta and slow oscillations compared to SPW-R-unchanged neurons.•These results provide new insight on the interaction between a lSuM neuronal population and hippocampus during SPW-Rs.