NEURAL MECHANISMS OF COROLLARY DISCHARGE AND DOPAMINERGIC MODULATION IN ZEBRAFISH VISUOMOTOR PROCESSING

As animals move, their sensory systems must distinguish between external stimuli and the sensory consequences arising from their own motion. This distinction is mediated by corollary discharge (CD), internally generated signals that encode motor commands and predict their expected sensory outcomes. CD plays a fundamental role in motor learning, sensory prediction, and perceptual stability. Disruptions in CD mechanisms have been implicated in sensory misrepresentation and perceptual distortions.
In recent work, we identified a CD mechanism in the zebrafish optic tectum (homologous to the mammalian superior colliculus), where motor-related inhibitory signals modulate visual processing during self-motion [1]. Whole-cell patch clamp recordings revealed an inhibitory synaptic signal temporally linked to swim bouts, which counteracts self-induced excitatory visual input and transiently suppresses tectal spiking activity. Calcium imaging further localized these motor-related signals to the tectal neuropil and torus longitudinalis, suggesting that CD signals reach the tectum via this pathway. These findings provide mechanistic insights into saccadic suppression, a phenomenon widely observed across species.
Ongoing research aims to further elucidate CD signaling in zebrafish. Using targeted patch-clamp recordings, we investigate the structure-function relationship of neuron types involved in CD transmission, focusing on tectal neurons that encode motor activity and sign-convert swim-associated excitatory inputs into inhibitory signals. Second, we examine the role of dopaminergic projections within the tectum. Together, these studies provide novel insights into the interaction between CD and neuromodulatory mechanisms in shaping sensorimotor processing, with implications for understanding perception, motor control, and adaptive behavior.
[1] Ali*, Lischka*, et al, Nature Commun 2023