Dynamic changes in interneuron morphophysiological properties mark the maturation of hippocampal network activity

Area of Science:

• Neuroscience
• Developmental Biology
• Cellular Neuroscience

Background:

• Early postnatal development features spontaneous patterned neuronal activity crucial for circuit maturation.
• Initially, synchronous plateau assemblies (SPAs) dominate, later replaced by synapse-driven giant depolarizing potentials (GDPs).

Purpose of the Study:

• To investigate the correlation between sequential network activities (SPAs and GDPs) and single-cell property modifications.
• To understand the morphophysiological changes in CA3 GABAergic interneurons during network maturation.

Main Methods:

• Inducible genetic fate mapping in rodents.
• Studied the morphophysiological properties of single CA3 GABAergic interneurons.
• Analyzed intrinsic properties, synaptic input, soma size, and membrane protrusions.

Main Results:

• GABAergic neuron involvement shifts from SPAs to GDPs during network maturation.
• Individual neuron participation in SPAs correlates with their temporal origin.
• SPA-to-GDP transition is paralleled by significant maturation in GABAergic neuron morphophysiology.
• Interneurons in SPAs exhibit immature intrinsic properties, diverse synaptic inputs, and distinct morphological features compared to those in GDPs.

Conclusions:

• A developmental switch in GABAergic interneuron morphophysiology accompanies the transition from SPAs to GDPs.
• This cellular maturation underpins the emergence of synapse-driven network oscillations in the developing hippocampus.