Distributed Dynamics and Cognition in the Brain

The last lecture will cover ongoing research on large-scale brain circuit modeling for understanding distributed dynamics and cognitive functions. First, our model has been expanded to incorporate a laminar structure, with layer-dependent projections as well as synchronous neural population oscillations. This advance will enable us to investigate dynamical interplay between bottom-up information processing and top-down feedback signaling. Second, we re-examined the classic problem of signal propagation along the cortical hierarchy in an anatomically-constrained large-scale cortex model endowed with many feedback loops. Surprisingly, our model displays a thresholding phenomenon for access to the prefrontal cortex and distributed dynamics akin to the global workspace model of conscious report. Third, analysis of densely connected multi-regional cortical circuit urged us to consider how information is routed to the right place at the right time in such a complex system, flexibly  according to behavioral demands. I will propose a circuit disinhibitory motif instantiated by three (PV+, SOM+ and VIP+) subtypes of inhibitory neurons as a mechanism for gating inter-areal communication. Fourth, model simulation of a delayed response task revealed working memory representations distributed across cortical areas. The theory of distributed self-sustained persistent activity patterns opens the door for elucidating cognitive processes, as well as their deficits associated with mental illness, in a large-scale multi-regional brain system.