Mapping mesoscale cortical connectivity in monkey sensorimotor cortex with optical imaging and microstimulation.

Area of Science:

• Neuroscience
• Systems Neuroscience
• Cortical Circuitry Mapping

Background:

• Understanding in vivo cortical circuitry at the mesoscale is crucial for deciphering brain function.
• Existing methods may have limitations in precisely mapping interareal functional connectivity.

Purpose of the Study:

• To introduce and validate a novel approach for mapping interareal functional connectivity in the cerebral cortex.
• To investigate the functional connections within and between somatosensory cortical areas in vivo.

Main Methods:

• Utilized electrical intracortical microstimulation (ICMS) to evoke neural activity.
• Employed optical imaging of intrinsic signals (OIS) to detect and map activation patterns.
• Applied the combined ICMS-OIS technique in anesthetized squirrel monkeys.

Main Results:

• ICMS evoked focal, stimulation intensity-dependent activations.
• Mapped interareal functional connections within somatosensory areas (3b, 1, 2, 3a, M1) consistent with known anatomical connectivity.
• Identified patchy intra-areal and inter-areal activation patterns (200-300 μm patches), suggesting specific circuit organization.

Conclusions:

• ICMS combined with OIS is a powerful novel approach for in vivo mesoscale mapping of cortical circuitry.
• The observed connectivity patterns largely align with anatomical feedforward pathways, with potential feedback contributions.
• This technique provides a valuable tool for studying functional brain networks.