Dissecting aminergic contributions to visual discrimination learning in honey bees using a virtual reality paradigm

The honey bee is a powerful model for studying visual cognition, yet the neuromodulatory mechanisms underlying visual learning remain poorly understood due to the reliance on free-flying paradigms that preclude neural interventions. Here, we used a closed-loop virtual reality (VR) system in which tethered bees walk on a spherical treadmill to navigate a controlled 3D visual environment, providing unprecedented access to the nervous system. Using neuropharmacological manipulations, we investigated the role of dopaminergic and serotonergic signaling in visual discrimination learning. Dopamine receptor activation accelerated the emergence of stable discrimination, whereas receptor blockade impaired both acquisition and short-term memory. In contrast, serotonergic manipulations produced subtler, dose-dependent effects. Enhancing serotonergic signaling through serotonin injections did not support the acquisition or expression of stable visual discrimination at either concentration tested while blockade of serotonergic receptors resulted in a non-monotonic learning pattern. These findings identify dopamine as a key reinforcement signal and serotonin as a modulatory factor, and highlight the potential of VR approaches to link neural mechanisms, cognition, and behavior.