Effects of intrastriatal injections of scopolamine on appetitive behavior

Anatomical specificity within rat striatum for the dopaminergic modulation of DRL responding and activity

The direct application of microgram quantities of crystalline dopamine, D-amphetamine, or scopolamine to the ventral anterior region of the neostriatum of rats decreased response efficiency on a 'differential reinforcement of low rate' 10 sec schedule of reinforcement. Similar applications to the dorsal globus pallidus or posterior striatum either did not alter or increased response efficiency. A comparison of dose-response functions for injections of dopamine in solution into ventral anterior, central and posterior striatum confirmed that only injections into ventral anterior striatum (VAS) decreased response efficiency on the DRL schedule. The same striatal map was found for the dopamine-induced increase in spontaneous locomotor activity in tilt boxes. It was concluded that dopaminergic transmission in ventral anterior striatum, in contrast to the other striatal and pallidal sites tested, is involved in the modulation of behavioral arousal.

Behavioral and biochemical effects of knife cuts that preferentially interrupt principal afferent and efferent connections of the striatum in the rat

Knife cuts were made that preferentially interrupted (a) the nigrostriatal pathway; (b) pallidofugal projections to the lower brainstem; (c) caudate-pallidal interconnections; and (d) fibers entering or leaving the striatum ventrally. The effects of these cuts on conditioned (shuttle box) avoidance, passive avoidance, swimming escape, sucrose-rewarded alley running, locomotor activity, and various measures of sensory-motor function were examined. The norepinephrine, dopamine and serotonin content of the striatum, residual forebrain and hypothalamus were determined following the completion of behavioral testing. The pattern of results suggests that striatal functions which are significantly influenced by several afferent and efferent connections are essential for the acquisition and, perhaps, execution of complex behavior in appetitive as well as aversive test paradigms. A special role for the dopaminergic afferents to the striatum was not established in these tests.

Frontal-striatal control of behavioral inhibition in the rat

The direct application of crystalline dopamine, D-amphetamine or scopolamine in microgram quantities to the ventral anterior region of the corpus striatum (VAS) of rats increased their responding for food on a modified DRL-30 sec schedule of reinforcement. Similar applications of norepinephrine were less effective than dopamine, while the anticholinesterase eserine depressed responding. Electrolytic lesions of the ventrolateral, but not the dorsomedial, prefrontal cortex of rats also increased their response rates. These results were interpreted as being consistent with the idea of a dopamine-acetylcholine antagonism in the VAS whose net output modulate behavioral inhibition. This striatal mechanism may be influenced by the ventrolateral prefrontal cortex.