Research findings related to the functional significance of the gustatory neocortical system of the rat are reviewed and interpreted. Studies of gustatory neocortex (GN) involvement in taste-related cognitive processes are emphasized after briefly reviewing GN anatomy and physiology. Evidence is presented supporting the conclusion that the GN contributes relatively little to fundamental taste reactivity, but is deeply involved in cognitive (learning and memorial) taste processes; that is, "reactive salience" to taste stimuli is preserved following GN ablation, while "associative salience" is markedly degraded. Apparent functional similarities between GN and other sensory neocortical areas are emphasized throughout the paper, and a hierarchical view of gustatory system functioning is addressed.Patton began his 1950 review of the chemical senses by pointing out that taste and smell essentially had been neglected relative to the other sensory systems. As a partial explanation for this neglect, he men-

This article presents the proceedings of a symposium at the 2002 RSA/ISBRA Meeting in San Francisco, California, co-organized by Julie A. Mennella and Alexander A. Bachmanov of the Monell Chemical Senses Center. The goal of this symposium was to review the role that chemosensory factors (taste, smell, and chemical irritation) play in the perception, preference, and consumption of alcohol. The presented research focused on both humans and laboratory animals and used a variety of approaches including genetic, developmental, pharmacological, behavioral, and psychophysical studies. The presentations were as follows: (1) Introduction and overview of the chemical senses (Julie A. Mennella and Alexander A. Bachmanov); (2) Taste reactivity as a measure of alcohol palatability and its relation to alcohol consumption in rats (Stephen W. Kiefer); (3) Early learning about the sensory properties of alcohol in laboratory animals (Juan Carlos Molina); (4) Early learning about the sensory properties of alcohol in humans (Julie A. Mennella); (5) Genetic dissection of the ethanol-sweet taste relationship in mice (Alexander A. Bachmanov and Michael Tordoff); and (6) Human genetic variation in taste: connections with alcohol sensation and intake (Valerie B. Duffy and Linda M. Bartoshuk). The symposium concluded with a general discussion.

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Our previous studies have shown that the selective dopamine D3 receptor antagonists SB-277011A or NGB 2904 significantly attenuate cocaine self-administration under a progressive-ratio reinforcement schedule and cocaine-, methamphetamine- or nicotine-enhanced brain stimulation reward. However, the poor bioavailability of SB-277011A has limited its potential use in humans. In the present study, we investigated the effects of the novel D3 receptor antagonist PG01037 on methamphetamine self-administration, methamphetamine-associated cue-induced reinstatement of drug seeking and methamphetamine-enhanced brain stimulation reward. Rats were allowed to intravenously self-administer methamphetamine under fixed-ratio 2 and progressive-ratio reinforcement conditions, and then the effects of PG01037 on methamphetamine self-administration and cue-induced reinstatement were assessed. Additional groups of rats were trained for intracranial electrical brain stimulation reward and the effects of PG01037 and methamphetamine on brain stimulation reward were assessed. Acute intraperitoneal administration of PG01037 (3, 10, 30 mg/kg) failed to alter methamphetamine or sucrose self-administration under fixed-ratio 2 reinforcement, but significantly lowered the break-point levels for methamphetamine or sucrose self-administration under progressive-ratio reinforcement. In addition, PG01037 significantly inhibited methamphetamine-associated cue-triggered reinstatement of drug-seeking behavior and methamphetamine-enhanced brain stimulation reward. These data suggest that the novel D3 antagonist PG01037 significantly attenuates the rewarding effects as assessed by progressive-ratio self-administration and brain stimulation reward, and inhibits methamphetamine-associated cue-induced reinstatement of drug-seeking behavior These findings support the potential use of PG01037 or other selective D3 antagonists in the treatment of methamphetamine addiction.

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Rats reared in an IC show greater proclivity to respond operantly for 10% ethanol compared with rats raised in either SC or EC (which did not differ from each other). These findings agree with a number of studies that have shown isolate reared animals to consume greater amounts of ethanol compared with their socially reared counterparts yet contrast some studies showing EC animals consume greater amounts of ethanol than IC rats. The current findings illustrate that rearing environment also plays an important role in an animal's proclivity to respond for ethanol.

We have previously reported that selective blockade of brain dopamine D3 receptors by SB-277011A significantly attenuates cocaine self-administration and cocaine-induced reinstatement of drug-seeking behavior. In the present study, we investigated whether SB-277011A similarly inhibits methamphetamine self-administration and methamphetamine-induced reinstatement to drug-seeking behavior. Male Long–Evans rats were allowed to intravenously self-administer methamphetamine (0.05 mg/kg/infusion) under fixed-ratio 2 (FR2) or progressive-ratio (PR) reinforcement conditions, and some rats were tested for methamphetamine-induced reinstatement of drug-seeking behavior after extinction of self-administration. The effects of SB-277011A on each of these methamphetamine-supported behaviors were then tested. Acute intraperitoneal (i.p.) administration of SB-277011A failed to alter methamphetamine self-administration under FR2 reinforcement, but significantly lowered the break-point for methamphetamine self-administration under PR reinforcement. SB-277011A also significantly inhibited methamphetamine-triggered reinstatement of extinguished drug-seeking behavior. Overall, these data show that blockade of dopamine D3 receptors by SB-277011A attenuates the rewarding and incentive motivational effects of methamphetamine in rats, supporting the development of selective dopamine D3 antagonists for the treatment of methamphetamine addiction.

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