Differential effects of unilateral and bilateral caudate lesions on side preference and passive avoidance behavior in rats.

The effects of unilateral and bilateral caudate lesions on side preferences, passive avoidance learning and locomotor activity were determined in rats. Unilateral lesions ipsilateral to preoperative side preferences increased side preference and facilitated passive avoidance learning. Contralateral lesions reversed side preferences and impaired passive avoidance learning.

Acute effects of morphine on regional brain levels of acetylcholine in mice and rats.

Morphine increased levels of acetylcholine in mouse striatum in a dose-dependent manner, the increase occurring at the lowest dose previously found to produce analgesia and coinciding with the time of peak analgesic effect. Naloxone blocked this increase. After repeated injections of high doses of morphine, no effect was seen.

Drug-induced rotation in rats without lesions: behavioral and neurochemical indices of a normal asymmetry in nigro-striatal function.

Normal unoperated rats were tested for rotation (i.e., circling behavior) in a spherical "rotometer" and dose-response relationships were generated using d-amphetamine, apomorphine, L-Dopa, haloperidol, and scopolamine.

Differential effects of unilateral and bilateral caudate lesions on side preferences and timing behavior in rats.

Rats were trained to bar press on a differential-reinformcement-of-low-rate 16-sec (DRL 16) schedule for water reinforcement. On alternate days, rats were tested in the presence or absence of a light that signaled the availability of reinforcement. Rats were allowed to bar press on either of two levers (left and right).

Dopamine metabolism in the nucleus accumbens: the effect of clozapine.

Dopamine metabolism in the nucleus accumbens of the rat was studied by gas chromatographic quantitation of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). The ratio of DOPAC/HVA in the nucleus accumbens was significantly greater than the same ratio in the striatum. Dose-response curves for the increase in DOPAC and HVA in the nucleus accumbens and striatum 2 h after clozapine were generated.

Factors influencing tolerance to d-amphetamine-induced anorexia in rats.

Three experiments were concerned with tolerance to anorexia induced by d-amphetamine. In experiment 1, one group of rats on a 2 hr food deprivation schedule received 2 mg/kg of d-amphetamine 15 min before eating every other day for a month. A second group of rats on a similar schedule received the same dose of d-amphetamine immediately after eating.

Differential sensitivity to apomorphine and clonidine following frontal cortical damage in rats.

Rats trained to bar-press on a FI 15 sec schedule for water reinforcement were administered various doses of apomorphine (0.25-10 mg/kg) and clonidine (0.002-0.

Dopaminergic and cholinergic influences on morphine self-administration in rats.

Various doses of apomorphine, haloperidol, pilocarpine and scopolamine were administered i.p. to rats self-administering i.

Relationship of rats' spatial preferences to effects of d-amphetamine on timing behavior.

Rats were trained to bar-press on a differential reinforcement of low rate 16 sec (DRL 16) schedule for water reinforcement. On alternate days, rats were tested in the presence or absence of a light which signaled the availability of reinforcement. Rats were allowed to bar-press on either of two levers (left and right).

Improved automated apparatus for recording rotation (circling behavior) in rats or mice.

An improved automated apparatus for measuring rotation (circling behavior) is described. The apparatus may be designed for either mice or rats. The logic circuit differentiates between complete 360 degrees rotations and incomplete oscillatory turns; preliminary data indicate that this distinction has functional significance.