Intracortical pathways mediate nonlinear fast oscillation (>200 Hz) interactions within rat barrel cortex

Area of Science:

• Neuroscience
• Sensory Processing
• Somatosensation

Background:

• Whisker evoked fast oscillations (>200 Hz) in the rodent posteromedial barrel subfield are crucial for rapid multiwhisker stimulus integration.
• The precise neural pathways, particularly intracortical networks, mediating these fast oscillations remain incompletely understood.

Purpose of the Study:

• To investigate the role of intracortical networks in mediating fast oscillation (FO) interactions within the rodent somatosensory cortex.
• To determine how horizontal connectivity along barrel rows contributes to the integration of tactile information.

Main Methods:

• Experiments were conducted on anesthetized rats.
• A cortical incision was surgically introduced between whisker representation sites.
• Simultaneous whisker stimulation was used to record and analyze fast oscillations (FOs) and their interactions.

Main Results:

• Intact cortex showed supralinear responses for FOs between simultaneously stimulated whiskers aligned in a row.
• Supralinear responses were also observed for adjacent whiskers in an arc, but not nonadjacent ones.
• A cortical cut abolished supralinear interactions for FOs along whisker rows, indicating reliance on horizontal connections.

Conclusions:

• Horizontal intracortical pathways exclusively mediate fast oscillation (FO)-related integration of tactile information.
• There is a significant bias for stronger long-range connectivity along barrel rows within the rodent somatosensory cortex.