State-dependent cell-type-specific membrane potential dynamics and unitary synaptic inputs in awake mice.

Area of Science:

• Neuroscience
• Cellular Neuroscience
• Systems Neuroscience

Background:

• Cell-type-specific mechanisms underlying cortical network activity and behavior remain unclear.
• Inhibitory GABAergic neurons play critical roles in regulating cortical function.

Purpose of the Study:

• To investigate the state-dependent cellular and synaptic properties of distinct inhibitory neuron classes in the mouse barrel cortex.
• To correlate membrane potential dynamics with cortical states and whisking behavior.

Main Methods:

• Whole-cell recordings from layer 2/3 parvalbumin- and somatostatin-expressing neurons in awake, head-restrained mice.
• Optogenetic stimulation of single excitatory neurons to measure unitary excitatory postsynaptic potentials (uEPSPs).
• Analysis of spontaneous membrane potential dynamics in relation to cortical states and whisking behavior.

Main Results:

• Parvalbumin-expressing neurons depolarized during active states (whisking, reduced LFP low-frequency activity).
• A subset of parvalbumin neurons showed increased uEPSP amplitude during active states.
• Somatostatin-expressing neurons hyperpolarized and reduced firing rates during active states, with no consistent change in uEPSP amplitude.

Conclusions:

• Distinct genetically-defined inhibitory neuron classes exhibit differential state-dependent activity patterns in the neocortex.
• These findings contribute to understanding how specific inhibitory neuron subtypes regulate cortical network states and behavior.