Place-independent behavioural correlates of hippocampal neurones in rats.

The broad diversity of discharge correlates of hippocampal neurones has provoked controversy. For example, purported behavioural correlates could, instead, be location selectivity (of 'place cells') that is secondarily modulated by sensory stimulation or ongoing movements. In rats trained to perform identical behaviours in four corners of a symmetrical arena, we found hippocampal pyramidal cells discharged selectively as the rats performed task-related behaviours regardless of spatial location. Since the ensemble of these hippocampal neurones comprehensively represented all stages of the task, we propose that each cell represents an element of the temporal organization of the animal's behaviour, complementing the place cell representations of elements of the structure of the environment.