Thalamo-insular basis for updating physiological needs
Physiological needs, such as thirst and hunger, produce powerful motivation for behaviors that are essential for survival. Yet, how the brain estimates these needs remains unknown. It is unclear whether the brain continuously monitors bodily signals to create real-time representations, or if existing internal representations are only updated when meaningful changes occur. To address this question, we manipulated thalamic internal sensory inputs to the interoceptive insular cortex. We found that inhibiting internal sensory inputs prevents the updating of insular cortex representations of thirst and hunger, thereby keeping its activity closer to its initial physiological need state. Consequently, cued feeding and drinking, as well as free consumption of food and water, persist beyond the current physiological need. We further show that insular cortex activity normally represents both predictions and sensory information. However, violating learned expectations evokes widespread need-specific prediction error signals. Our results thus reveal a thalamo-cortical basis for updating physiological needs in the brain.