Neural circuit

Interacting neurons and connections supporting a defined processing or behavioural function.

A model-dependent or experimentally tested influence of one neural system on another. Perturbing one region and measuring a remote change strengthens a causal interaction claim, although the influence may be indirect.

A proposed collection of observation–execution matching circuits. Shared activation in two imaging conditions is not by itself evidence that exactly the same individual neurons have mirror properties.

Inhibitory influence between systems in opposite cerebral hemispheres. It is a candidate mechanism in some recovery accounts, but opposite activation changes or improved behaviour after stimulation do not by themselves establish its direction and causal route.

An interacting loop linking cortical regions with basal ganglia output and thalamus. Structural connectivity, resting-state correlation and physiological information flow measure different aspects of such a circuit.

A circuit involving cerebral cortex and striatum, often understood within larger loops through basal ganglia and thalamus. Different loops can contribute to learning and selecting actions; involvement of one component does not imply exclusivity of the whole function.

A historically influential arrangement connecting hippocampal, mammillary, anterior thalamic and cingulate regions. James Papez proposed it in relation to emotion in 1937. Contemporary memory accounts require additional inputs and parallel connections; the diagram of a loop is not a proof that every connection has identical necessity.

A historical account linking medial temporal and diencephalic amnesia through an extended hippocampal system, associated with Jean Delay and Serge Brion. Important structures include the hippocampus, fornix, mammillary bodies and anterior thalamic nuclei. It overlaps the Papez circuit, but an explanatory claim about memory is not identical to the original proposal about emotion.^[ref]