Functional adaptation of cortical interneurons to attenuated activity is subtype-specific

Area of Science:

• Neuroscience
• Cellular Neuroscience
• Systems Neuroscience

Background:

• Neuronal homeostasis is crucial for brain function, involving cellular and network-level adaptations to activity changes.
• Distinguishing cell-autonomous from network-mediated homeostatic mechanisms is challenging in vivo.
• Sparse targeting of specific neuronal populations is key to dissecting these mechanisms.

Purpose of the Study:

• To investigate cell-autonomous regulation of neuronal excitability in vivo.
• To explore homeostatic plasticity in GABAergic interneurons.
• To develop and utilize a novel sparse in vivo targeting method.

Main Methods:

• Developed a novel in vivo approach for sparse labeling and activity manipulation.
• Targeted superficial caudal ganglionic eminence (CGE)-derived GABAergic interneurons.
• Expressed the inward rectifying potassium channel Kir2.1 to reduce neuronal activity.

Main Results:

• Kir2.1 expression cell-autonomously reduced neuronal activity in targeted interneurons.
• Observed specific developmental changes in electrophysiological properties and synaptic input.
• Did not find typical homeostatic scaling responses seen in pyramidal cells.
• Identified altered excitatory synaptic event kinetics in reelin-expressing interneurons.

Conclusions:

• Demonstrates the capacity of interneurons to autonomously regulate their excitability in vivo.
• Highlights unique homeostatic mechanisms in GABAergic interneurons compared to pyramidal cells.
• Provides foundational in vivo evidence for interneuron-specific homeostatic plasticity.