Striatum - Function

Function

Metabotropic dopamine receptors are present both on spiny neurons and on cortical axon terminals. Second messenger cascades triggered by activation of these dopamine receptors can modulate pre- and postsynaptic function, both in the short term and in the long term. The striatum is best known for its role in the planning and modulation of movement pathways but is also potentially involved in a variety of other cognitive processes involving executive function, such as working memory. In humans the striatum is activated by stimuli associated with reward, but also by aversive, novel, unexpected or intense stimuli, and cues associated with such events. Recent fMRI evidence suggests that the common property linking these stimuli, to which the striatum is reacting, is saliency under the conditions of presentation. A number of other brain areas and circuits are also related to reward such as frontal areas. Research at the Wellcome Trust Centre for Neuroimaging at UCL (University College London) shows it to be associated with novelty-related decision making behaviors.

For sources regarding saliency of the reward pathway (thought to be related to dopamine) one can look to the work of Dr. John D. Salamone (early to late 1990s) and Wolfram Schultz. The ventral tegmental dopaminergic neurons that innervate portions of the striatum have long been accepted to be the site of rewarding feeling. Intracranial stimulation studies from the 1960s show implants in this brain area will elicit bar pressing from rats for many hours at a time. However the collective works of researchers in the 1990s show that blocking dopamine receptors does not remove rewarding sensations, rather it affects how much the animal is willing to work, triggering more motivation to seek eventual reward rather than immediate reward.