Four neurons pattern brain-wide developmental activity through neuropeptide signaling.

Area of Science:

• Neuroscience
• Developmental Biology
• Molecular Biology

Background:

• Developing brains exhibit electrical activity prior to sensory input processing.
• Developmental neural activity is crucial for refining synaptic connections through patterned neuronal co-activation.

Purpose of the Study:

• To elucidate the cellular interactions and molecular mechanisms governing brainwide developmental activity.
• To understand how patterned stimulus-independent neural activity (PSINA) is established and regulated in the developing brain.

Main Methods:

• Investigated cellular interactions shaping brainwide developmental activity in Drosophila.
• Identified a specific population of ~2,000 Transient Receptor Potential Gamma (Trpγ+) neurons as an activity template.
• Characterized the role of four SIFamide (SIFa) neurons in patterning this activity template.

Main Results:

• SIFa neurons pattern the Trpγ+ neuron activity template, establishing brainwide activity cycles (PSINA).
• SIFa signaling modulates both SIFa and Trpγ+ neuron activity.
• A recurrent interaction between Trpγ+ and SIFa neurons sustains SIFa neuron activity.

Conclusions:

• Neuropeptide signaling, specifically SIFa, is central to shaping brainwide developmental activity.
• Synapse-free neuropeptide signaling is a key mechanism for refining synapse formation during development.
• This study highlights the role of the chemical connectome in the developing brain's neurophysiology.