Molecular programs guiding arealization of descending cortical pathways

Area of Science:

• Neuroscience
• Developmental Biology
• Molecular Biology

Background:

• Layer 5 extratelencephalic (ET) neurons are crucial for motor control and are implicated in neurological disorders.
• Two main subtypes, ETdist and ETprox, exhibit distinct cortical locations and subcortical projection targets.

Purpose of the Study:

• To elucidate the developmental mechanisms underlying the emergence of ET neuron subtypes.
• To identify the transcriptional programs governing ET neuron subtype specification and connectivity.
• To explore the potential for reprogramming ET neuron connectivity.

Main Methods:

• Cross-areal mapping of axonal projections in the mouse neocortex.
• Single-nucleus sequencing to identify developmental transcriptional programs.
• Postnatal in vivo knockdown of subtype-specific transcription factors.

Main Results:

• Identified distinct developmental trajectories for ETdist and ETprox neurons, including axon pruning and de novo generation.
• Characterized subtype-specific developmental transcriptional programs.
• Demonstrated successful reprogramming of ET neuron connectivity by manipulating transcription factors.

Conclusions:

• ET neuron diversity arises from specific developmental dynamics and transcriptional programs.
• Gene regulatory networks controlling ET neuron target specificity can be therapeutically targeted.
• Findings provide insights into motor pathway development and potential treatments for related disorders.