Internal state dynamics shape brainwide activity and foraging behaviour.

Area of Science:

• Neuroscience
• Animal Behavior
• Systems Neuroscience

Background:

• Persistent internal brain states dynamically modulate animal behavior, especially during complex tasks like foraging.
• Understanding the neural mechanisms maintaining these states, driving transitions, and influencing neuromodulation is crucial for explaining behavior.

Purpose of the Study:

• To investigate the neural basis of persistent internal states in zebrafish larvae during foraging.
• To identify the brain networks and neuronal populations responsible for maintaining and transitioning between behavioral states.

Main Methods:

• Utilized tracking microscopy for whole-brain neuronal activity monitoring in freely moving zebrafish larvae.
• Observed spontaneous behavioral state alternations during foraging for live prey.

Main Results:

• Identified two distinct internal states: exploitation (inhibited locomotion, promoted hunting) and exploration (promoted locomotion, suppressed hunting).
• Discovered a dorsal raphe subpopulation with persistent activity encoding the exploitation state.
• Revealed a stochastically activated nonlinear dynamical system involving state-encoding neurons and a trigger network, correlating with altered sensorimotor transformations.

Conclusions:

• Zebrafish exhibit spontaneous alternations between exploitation and exploration states during foraging.
• A specific neural circuit, including dorsal raphe neurons, underlies state maintenance and transitions.
• These internal states act as hidden variables that globally retune sensorimotor processing, impacting motivation and decision-making in foraging behavior.