An applicable and efficient retrograde monosynaptic circuit mapping tool for larval zebrafish.

An efficient retrograde monosynaptic circuit mapping method in larval zebrafish reveals up to 20 inputs per neuron with low cytotoxicity.

• Why it matters: Understanding neural circuits in larval zebrafish is crucial for in vivo brain activity studies, but existing tracing techniques are limited in efficiency and specificity.
• What they did: The researchers developed a method using EnvA-pseudotyped glycoprotein-deleted rabies viruses, optimizing factors like virus strain and temperature, achieving high tracing efficiency and cell viability.
• The result: This approach enables detailed circuit mapping, including cell-type-specific input tracing, exemplified by uncovering cerebellar connections and subtype preferences, advancing functional neurobiology in zebrafish.