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Objective Multimodal information processing is fundamental to hippocampal functions, including learning and memory and cognitive processing of information regarding space, time and relationships among cues.But its neural substrates are much less understood.Methods Here we investigated this issue by performing in vivo whole-cell recordings from CA1 pyramidal cells (PCs) of anaesthetized adult rats.Results We found that a brief flashing of visual stimulus evoked significant synaptic responses in a small fraction of CA1 PCs (~30%).Interestingly, when intracellularly treated with CS+/TEA, all neurons exhibited robust synaptic responses to the same stimulus, and most (~80%) were excited.This increase in the proportion of responsive cells was abolished by intracellular application of MK801—a NMDA receptor blocker.Likewise, when voltage-clamped at about +40 mV, ~80% PCs exhibited outward currents in response to the flashing stimulation, which were also blocked by the intracellular treatment of MK801.Conclusion Thus, a simple sensory cue targets widespread CA1 PCs at their functional/silent synapses.It may allow the largely unexplored flexibility of the distribution of hippocampal neuronal ensembles to represent and memorize the same information in CA1 in different hippocampus-dependent tasks.