Ignacio Rebollo, PhD | Gut signals as modulators of brain state and cognition

The same brain can think, feel, and perform differently from one hour to the next. Cognitive neuroscience has traditionally explained this variability through fluctuations in neural activity within the brain itself. Yet the brain is continuously embedded within bodily signals that convey information about physiological state and energy availability. In this talk, I will propose that gut–brain communication contributes to fluctuations in brain function and mental states through two complementary temporal channels. First, rhythmic gastric activity provides a fast interoceptive signal unfolding over tens of seconds. I will present evidence from electrogastrography and neuroimaging showing that this rhythm is coupled to large-scale hemodynamic and electrophysiological brain activity during wakefulness and sleep. I will also show that stomach–brain coupling decreases during highly arousing video stimuli, motivating the possibility that it acts as an “arousal dial” tracking ongoing brain state. Second, I will introduce a complementary model in which metabolic hormones provide a slower channel of gut–brain communication. Fluctuating over minutes to hours, these signals convey information about energy availability and may act as an “energy gauge,” shaping motivation, reward, affect, and cognition. Together, these fast and slow gut-derived signals offer distinct routes through which bodily state may shape brain dynamics, cognition, mood, and mental health.