Resting fMRI functional connectivity reflects fluctuations in inhibitory interneuron activity

Area of Science:

• Neuroscience
• Systems Neuroscience
• Computational Neuroscience

Background:

• Primate brain function depends on interconnected cortical networks.
• Resting-state functional magnetic resonance imaging (fMRI) is a common tool to identify these networks via correlated brain activity.
• The specific neuronal populations contributing to fMRI signals remain unclear.

Purpose of the Study:

• To investigate the relationship between distinct neuronal activity and fMRI functional connectivity.
• To determine which neural subtypes correlate with local and brain-wide fMRI signals.

Main Methods:

• Concurrent electrophysiological (single-unit) recordings and fMRI were performed in macaques at rest.
• Neuronal action potential waveforms were used to classify cell types (putative excitatory vs. inhibitory).
• Correlations between neural activity and fMRI signals were analyzed.

Main Results:

• Putative excitatory neurons showed mixed correlations (positive and negative) with local fMRI signals.
• All putative inhibitory interneurons exhibited positive correlations with local fMRI signals.
• One subclass of inhibitory interneurons displayed brain-wide correlations matching conventional fMRI functional connectivity.

Conclusions:

• Inhibitory interneuron activity closely aligns with resting-state fMRI fluctuations.
• Specific interneuron subclasses may be key drivers of the brain-wide functional connectivity observed in fMRI.
• Understanding neuronal contributions refines the interpretation of fMRI-based brain network mapping.