Macaque claustrum and hierarchical cortical processing – MACLAU

Early investigations of the claustrum reported an exceptionally wide-spread cortical connectivity that led to high speculations on its role in higher cognitive functions. Our recent results on the macaque claustrum indicates an extensive core structure with notably a regionalization of cortical projections and transcriptomically defined cell-types, some of which being macaque-specific. In addition, our tract tracing investigations show that in macaque the high-levels of convergence-divergence of claustral-cortical interactions ensures an exceptionally high centrality of the claustrum in the cortical graph. These anatomical findings suggest that the claustrum plays a unique role as hub in the macaque brain, and that the functional roles of claustrum in macaque may differ from those described in mouse. However, while the hub function of the claustrum ensures integration of information across functionally specialized cortical modules, its widespread and uniformly strong outputs to the cortex would seem at odd with the high functional specialization needed for high-order cognition. Our recent findings strongly support that this functional specialization is ensured by the observed strong heterogeneity of claustral-cortical projection cell-types. Preliminary simultaneous multi-site single unit recordings in claustrum and multiple cortical areas shows a high-centrality of the claustrum. Here we build up on these findings in order to make progress in analyzing the role of the claustrum in hierarchical processing. We will exploit our recent results on claustral-cortical projection cell-types to develop the viral vectors required to causally assess the functional roles of these cortical claustrum pathways in hierarchical processing during cognitive tasks in awake behaving macaque monkey.