Thalamostriatal synapses-another substrate for dopamine action?

Over the years since the discovery of dopamine in the neostriatum, we have learned much about the anatomy of this large subcortical nucleus. In rodents, it is one nucleus penetrated by many fibers from the cerebral cortex. In larger animals and in humans, the area is split by a bundle of mainly corticofugal axons into the caudate nucleus and putamen. Dopamine input to both is similar and except for the details of cortical afferents to the two parts the striatum seems to act as one structure. Its main function is expected to be the transfer of the information carried in its cortical inputs onward through the basal ganglia. Diseases of this area of brain are associated with movement disorders and much is made of the action of dopamine on the long-term stability of corticostriatal synapses. The cortex is not at all the only input to the area, however, and the thalamus has almost as many synapses with striatal output neurons as has the cortex. This chapter summarizes the contributions to the study of the involvement of thalamostriatal inputs presented at Dopamine 2013 and emphasizes that this input, though largely ignored, has important lessons for those interested in understanding the function of the basal ganglia.