A genetic approach to trace neural circuits.

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Mammalian nervous systems comprise billions of interconnected neurons forming complex neural circuits.
• Understanding neural circuit connectivity is crucial for deciphering nervous system function.

Purpose of the Study:

• To develop and validate a genetic approach for charting neural circuits using a transneuronal tracer.
• To investigate the potential of genetically targeted barley lectin expression for mapping neuronal pathways.

Main Methods:

• Utilized an olfactory-specific promoter to express barley lectin in sensory neurons of transgenic mice.
• Tracked lectin transport anterogradely and retrogradely through neuronal axons and across synapses.
• Assessed potential adverse effects of lectin expression on neuronal function and development.

Main Results:

• Barley lectin was successfully transported from olfactory sensory neurons to the olfactory bulb and cortex.
• Retrograde transport to neuromodulatory brain areas was observed.
• No adverse effects were detected on odorant receptor gene expression, axon targeting, or neuronal signaling.
• Prenatal transneuronal transfer was observed in the odor-sensing pathway, but not the pheromone-sensing pathway.

Conclusions:

• Genetically targeted barley lectin serves as an effective transneuronal tracer for mapping neural circuits.
• This technology is applicable to diverse neural systems and valuable for studying specific neuronal subsets and in utero connectivity development.