What resolves this contention: Whether cortico-basal-ganglia-thalamic loops are…

What resolves this contention: Whether cortico-basal-ganglia-thalamic loops are strictly parallel and segregated (Alexander/DeLong canon) or whether functionally distinct loops cross over via SNr/thalamic open-loop pathways. Aoki and the 2021 mouse CBGT mapping show open and reciprocal cross-loop connectivity that the strictly parallel model excludes. / From earlier data it had appeared that the basal ganglia served primarily to integrate diverse inputs from the entire cerebral cortex and to funnel these influences, via the ventrolateral thalamus, to the motor cortex (Allen & Tsukahara 1974, Evarts & Thach 1969, Kemp & Powell 1971). / Despite largely closed loops within each functional domain, we discovered a unidirectional influence of the limbic over the motor loop via ventral striatum-substantia nigra (SNr)-motor thalamus circuitry.