Long-range projections coordinate distributed brain-wide neural activity with a specific spatiotemporal profile

Area of Science:

• Neuroscience
• Systems Neuroscience
• Computational Neuroscience

Background:

• Understanding large-scale brain interactions and spatiotemporal neural activity patterns is crucial for deciphering brain functions and behavior.
• Limited knowledge exists regarding the spatiotemporal properties of long-range neuronal networks.

Purpose of the Study:

• To investigate brain-wide neural activity patterns evoked by stimulating ventral posteromedial (VPM) thalamo-cortical excitatory neurons.
• To elucidate the role of low-frequency neural activity in large-scale brain connectivity and functional integration.

Main Methods:

• Combined optogenetic stimulation and functional MRI (fMRI) to examine brain-wide neural activity.
• Electrophysiological recordings to assess temporal interactions across neuronal projections.
• Stimulation of posteromedial complex thalamo-cortical excitatory neurons to compare distinct network activation profiles.

Main Results:

• Low-frequency (1 Hz) VPM stimulation evoked robust bilateral fMRI activation in visual, somatosensory, and auditory cortices, unlike high frequencies (5-40 Hz).
• Electrophysiology revealed long temporal window interactions across thalamo-cortical, cortico-cortical, and callosal projections at low frequencies.
• VPM stimulation enhanced visually evoked fMRI activation in the superior colliculus, indicating subcortical modulation of visual processing by low-frequency VPM activity.

Conclusions:

• Low-frequency neural activity is a key regulator of large-scale, brain-wide connectivity and interactions via long-range excitatory projections.
• This mechanism coordinates the functional integration of remote brain regions, contributing to the neural basis of long-range functional connectivity observed in resting-state fMRI.