Sparse postnatal labeling and quantification of superficial cortical cell synapses in the mouse neocortex

Area of Science:

• Neuroscience
• Cell Biology
• Molecular Biology

Background:

• Understanding neuronal connectivity is crucial for deciphering brain function.
• Quantifying presynaptic bouton density provides insights into synaptic plasticity and network dynamics.
• Existing methods may lack the precision or specificity required for detailed analysis of cortical interneurons.

Purpose of the Study:

• To establish a robust strategy for measuring presynaptic bouton density in superficial mouse neocortical neurons.
• To enable precise quantification of synaptic structures along axonal processes.
• To provide a versatile protocol adaptable to various neuronal cell types.

Main Methods:

• Neonatal pial-surface electroporation for sparse labeling of individual postmitotic cells.
• Development of custom-made computational code for automated quantification of bouton density.
• Application of the method to somatostatin-positive cortical interneurons.

Main Results:

• Successful sparse labeling of individual neurons in the mouse neocortex.
• Validated custom code for accurate and efficient quantification of presynaptic bouton density.
• Demonstrated the applicability of the strategy to a major population of cortical interneurons.

Conclusions:

• The presented strategy offers a reliable approach for assessing presynaptic bouton density in cortical neurons.
• This method can be adapted to study other neuronal populations, advancing the field of neurobiology.
• The protocol facilitates detailed investigations into neuronal structure-function relationships.