CORRELATION BETWEEN BRAIN STATE FLUCTUATIONS AND INTESTINAL MOTOR ACTIVITY IN FREELY BEHAVING RATS

While the brain-gut axis is crucial for long-term metabolism, emotion, and cognition, the precise interaction between rapid changes in brain states and ongoing intestinal motor activity remains poorly understood. Here, we investigated the temporal relationship between brain state fluctuations and intestinal motility by establishing a system for simultaneous brain and gut recordings in freely behaving rats. Local field potentials were recorded from the hippocampus, and intestinal motor activity was monitored using strain gauge transducers surgically sutured to the duodenum. The strain signals yielded rhythmic activity consistent with peristaltic motor activity, and periods of intestinal motility and quiescence were detected based on temporal structure in the intestinal strain signals. We observed that hippocampal sharp-wave ripples, a neural activity pattern implicated in memory processing, occurred less frequently during intestine-motile periods. These findings indicate that rapid fluctuations in brain states are coupled to intestinal motor activity. These associations were observed independently of overt body movements, suggesting that the detected coupling reflects coordinated physiological dynamics rather than behavioral confounds. Our results support a framework in which peripheral visceral dynamics is instantaneously linked to ongoing brain states.