Functional and Structural Properties of Highly Responsive Somatosensory Neurons in Mouse Barrel Cortex

Area of Science:

• Neuroscience
• Sensory processing
• Cortical circuits

Background:

• Sparse population activity is characteristic of neocortical sensory neurons.
• Understanding the mechanisms of sparseness requires linking in vivo neuronal activity to in vitro cellular properties.

Purpose of the Study:

• To identify and characterize highly responsive neurons in mouse L2/3 somatosensory cortex.
• To investigate the cellular and network properties distinguishing high responders (HRs) from less active neurons.

Main Methods:

• Two-photon calcium imaging to identify active neurons in vivo.
• Photoconvertible green fluorescent protein tagging for targeted patch-clamp recordings.
• Intracellular recordings and biocytin staining in brain slices to analyze electrophysiological and morphological properties.

Main Results:

• High responders (HRs) exhibited increased stimulus-evoked and spontaneous activity, elevated noise, and stronger population coupling.
• HRs showed reduced intrinsic excitability compared to less responsive neurons.
• No significant differences were found in other electrophysiological or morphological parameters.

Conclusions:

• Neuronal participation in stimulus encoding is largely determined by network connectivity.
• Cellular structure and intrinsic function play a lesser role in determining which neurons are activated.
• This study provides a direct link between in vivo activity and in vitro properties of specific neuronal populations.