Septo-hippocampal GABAergic signaling across multiple modalities in awake mice

The authors use two-photon Ca 2+ imaging of axonal boutons in hippocampal CA1 of behaving mice to monitor the activation of septo-hippocampal GABAergic boutons. They report that some sensory inputs are more effective than locomotion in driving firing by these long-range GABAergic projections. Hippocampal interneurons receive GABAergic input from the medial septum. Using two-photon Ca 2+ imaging of axonal boutons in hippocampal CA1 of behaving mice, we found that populations of septo-hippocampal GABAergic boutons were activated during locomotion and salient sensory events; sensory responses scaled with stimulus intensity and were abolished by anesthesia. We found similar activity patterns among boutons with common putative postsynaptic targets, with low-dimensional bouton population dynamics being driven primarily by presynaptic spiking.