Recurrent activity within microcircuits of macaque dorsolateral prefrontal cortex tracks cognitive flexibility

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Systems Neuroscience

Background:

• The dorsolateral prefrontal cortex (dlPFC) is crucial for higher cognitive functions like working memory and decision-making.
• Intracortical synaptic architectures within dlPFC, particularly the 'canonical' cortical microcircuit, are believed to be the neurobiological basis for these functions.
• Existing models struggle to explain microcircuit coordination *in vivo* due to the inability to dissociate intracortical and intercortical computations.

Purpose of the Study:

• To investigate the intrinsic features of isolated cortical microcircuit networks in the macaque dlPFC.
• To determine if spontaneous activity is maintained by microcircuit architecture independent of extrinsic connections.
• To explore the relationship between microcircuit excitability and cognitive performance.

Main Methods:

• Utilized high-density calcium imaging in ex vivo macaque dlPFC preparations.
• Applied perisulcal stimulation to evoke persistent activity in deep cortical layers.
• Analyzed spontaneous and evoked activity patterns within isolated microcircuit networks.

Main Results:

• Spontaneous neural activity is intrinsically maintained by microcircuit architecture, persisting without extrinsic input.
• Evoked persistent activity propagates through stochastic intracortical networks, generating predictable population events.
• Microcircuit excitability demonstrated a positive correlation with individual cognitive performance.

Conclusions:

• The intrinsic architecture of dlPFC microcircuits is sufficient to maintain spontaneous activity, a key feature for cognitive processing.
• Population-level neural events arise from predictable propagation patterns within largely stochastic networks.
• Synaptic architecture provides a measurable link between the physical structure of the brain and abstract cognitive capabilities.