Catecholamines and DOPAC in cortical and neostriatal regions during rats' learning of delayed alternation.

Dopamine, norepinephrine and DOPAC were measured in two cortical areas (the medial prefrontal and the posterolateral, Te2) and in the anterior and posterior neostriatum in rats which were exposed to three different experiences for three different lengths of time. One group learned delayed alternation and the two others served as controls. Throughout the training period all animals were housed in single cages. There was no significant effect of the kind of experience on any measure, but the length of exposure did affect some values: the amount of non-precursor dopamine was decreased significantly in both neostriatal samples. A significant increase of dopamine turnover and amount of norepinephrine was found in the Te2 area and in the posterior neostriatal sample. The observed changes are attributed to isolation stress. We conclude that although, as it has been described earlier, dopamine transmission is necessary for mediation of behavioural functions of the prefrontal system, it does not change quantitatively in the system during specific activity.