Sound-induced hyperpolarization of hippocampal neurons

The hippocampus is involved in episodic memory, which is composed of subjective experiences in the multisensory world; however, little is known about the subthreshold membrane potential responses of individual hippocampal neurons to sensory stimuli. Using in-vivo whole-cell patch-clamp recordings from hippocampal CA1 neurons in awake mice, we found that almost all hippocampal neurons exhibited a hyperpolarization of 1-2 mV immediately after the onset of a sound. This large-scale hyperpolarization was unaffected by the duration or pitch of the tone. The response was abolished by general anesthesia and a surgical fimbria-fornix lesion.