The optimized viral tracing tool can be leveraged to investigate the functional roles of different granule cell (GC) and Purkinje cell (PC) subtypes in zebrafish behavior and information processing by combining the tracing with functional imaging techniques. By infecting specific GC and PC subtypes with the optimized viral tool and conducting calcium imaging or electrophysiological recordings, researchers can monitor the activity of these neurons in response to various stimuli or behavioral tasks. This approach can provide insights into the functional connectivity and information processing within the cerebellar circuit, shedding light on the roles of different neuronal subtypes in zebrafish behavior. Additionally, the combination of viral tracing with optogenetic manipulation techniques can allow for the precise control of neuronal activity, enabling the investigation of causal relationships between specific neuronal subtypes and behavioral outcomes.