Striatum cortical inputs

A global view of consciousness is that it is generated throughout the entire brain, as a result of synchronisation of relevant neural networks. Specific systems or regions—for example the cerebral cortex, brainstem reticular formation and thalamic nuclei—may be key anatomical integrators. Areas with the most widespread interconnections are pivotal, and on this basis the cortex and thalamus are more relevant than cerebellum and striatum for example. Frontal cortex for example connects with every other brain region, both in terms of input and output, with 80% of such connections accounted for by cortico-cortical connections. Thalamic intralaminar nuclei are, in conjunction with the reticular nucleus, reciprocally connected to all cortical areas. By contrast the cerebellum has very few output pathways and striatal-cortical input is (via the thalamus) confined to frontal lobe. 

In the rat, the limbic or ventral striatum, which includes the ventral striatum proper and the ventromedial portion of the CPu, receives extensive input from limbic structures, such as the hippocampus and amygdala, as well as prefrontal cortical areas subserving limbic and autonomic functions (orbital, infralimbic, prelimbic and agranular insular fields) (see Section 7.2). In primates, the limbic striatum comprises the NAc and the most ventral parts of the caudate and the putamen and, as in the rat, receives input from the hippocampus and amygdala its cortical input is further defined by projections deriving from the orbitofrontal cortex and the anterior cingulate area. 

The topographic organization of cortical inputs to the striatum, of striatal outputs to the globus pallidus (external segment), internal segment of the globus pallidus (en-... 

Due to its relevance to an understanding of movement disorders, the motor circuit has received the most attention. This circuit is centered on somatosensory, motor and premotor cortices, which send projections to the motor portions of striatum. The connections between the striatum and the basal ganglia output nuclei (GPi/SNr) are organized into direct and indirect pathways [1]. The direct pathway is a monosynaptic projection between striatum and GPi/ SNr, while the indirect pathway is a polysynaptic connection that involves intercalated neurons in GPe and STN. Some striatofugal neurons may also collateralize more extensively, reaching GPe, GPi/SNr and STN. Other motor -related inputs to striatum and STN arise from the intralaminar thalamic nuclei, i.e. the centromedian and parafascicular nuclei (CM/Pf). 

Smith Y, Bennett BD, Bolam JP, Parent A, Sadikot AF. 1994. Synaptic relationships between dopaminergic afferents and cortical or thalamic input in the sensorimotor territory of the striatum in monkey. J Comp Neurol 344 1-19. 

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