Area-specific Modulation of Functional Cortical Activity During Block-based and Trial-based Proactive Inhibition

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Animal Behavior

Background:

• Animals can proactively inhibit behavioral responses based on environmental context.
• The neural mechanisms regulating proactive inhibition across different timescales are not fully understood.
• Cortical areas are implicated in proactive inhibition, but their specific roles remain unclear.

Purpose of the Study:

• To behaviorally and electrophysiologically characterize the temporal aspects of proactive inhibition in rats.
• To investigate how proactive inhibition is adaptively regulated by contextual changes on different timescales.
• To differentiate the neural mechanisms underlying block-based and trial-based proactive inhibition.

Main Methods:

• Utilized an improved stop-signal task paradigm with head-fixed rats.
• Alternated blocks of go-only trials (G-block) and go-and-stop trials (GS-block).
• Behaviorally assessed reaction times and electrophysiologically analyzed neuronal activity in motor cortices (M1, M2), posterior parietal cortex (PPC), and orbitofrontal cortex (OFC).

Main Results:

• Identified both block-based proactive inhibition (in GS-blocks) and trial-based proactive inhibition (after stop trials) through reaction time delays.
• Observed distinct neural activity patterns: OFC activity attenuated during block-based inhibition, while M1/M2 activity was enhanced during preparation and attenuated during execution.
• Found continuous OFC enhancement and transient PPC/M1 enhancement during motor decision/execution under trial-based proactive inhibition.

Conclusions:

• Two distinct types of proactive inhibition, block-based and trial-based, were identified in rodents.
• Different cortical circuits, involving the OFC, M1, M2, and PPC, underlie these distinct forms of proactive inhibition.
• These findings provide insights into the adaptive regulation of behavioral suppression based on environmental context.