Chemical and electrical stimulation of the caudate nucleus in freely moving cats: the role of dopamine

Behavioral effects of electrical stimulation of the medial part of the caput caudati were studied in freely moving cats in chronic experiments. These electrically evoked effects were also studied in animals locally pretreated with dexamphetamine, apomorphine, dopamine, 3-methoxytyramine, noradrenaline, serotonin, haloperidol,α-methyl-p-tyrosine, and procaine. Our data show that electrical stimulation of the medial part of the caput caudati results in behavioral responses similar to those evoked by dopamine application into the area, and that these responses are inhibited by blockade of the striatal dopamine system on the one hand, and facilitated by activation of the striatal dopamine system on the other hand. The importance of these data is discussed in view of the hypothesis that dopamine released from the ascending nigro-striatal pathways activates small inhibitory interneurons connecting the medial part with the anteroventral part of the caput caudati.