Jason Gallate

The motivation for beer in rats: effects of ritanserin, naloxone and SR 141716.

Abstract Rats were given two weeks of home cage access to either “near-beer” (a beverage that tastes like beer but contains <0.5% ethanol v/v) or near-beer with added ethanol (4.5% v/v), which is simply referred to as “beer”. The two groups of rats (near-beer and beer) were then trained on a “lick-based progressive ratio paradigm” in operant chambers in which an ever increasing number of licks had to be emitted for each successive fixed unit of near-beer or beer delivered. Break points (the ratio at which responding ceased) for near-beer and beer were approximately equal under baseline conditions. Rats were then tested for the effects of the 5HT2A/2C receptor antagonist ritanserin (0.625, 2.5 or 10 mg/kg), the opioid receptor antagonist naloxone (0.625, 2.5 or 10 mg/kg) or the cannabinoid CB1 receptor antagonist SR 141716 (0.3, 1 or 3 mg/kg). All three drugs caused a dose-dependent reduction of break-points and locomotor activity in both the beer and near-beer groups. However, the effects of SR 141716 and naloxone, but not ritanserin, on break-points were significantly more pronounced on rats drinking beer compared to those drinking near-beer. There were no such differential effects of any of the drugs on locomotor activity across the two groups. These results suggest that both SR 141716 and naloxone differentially affect the motivation to consume alcoholic beverages and may thus have potential as drugs for the treatment of alcohol craving.

Increased anxiety and impaired memory in rats 3 months after administration of 3,4-methylenedioxymethamphetamine ("ecstasy").

Male Wistar rats were administered either (a) a high dose regime of 3,4-methylenedioxymethamphetamine (MDMA) (4 x 5 mg/kg, i.p. over 4 h on each of 2 consecutive days), (b) a moderate dose regime of MDMA (1 x 5 mg/kg on each of 2 consecutive days), (c) D-amphetamine (4 x 1 mg/kg over 4 h on each of 2 days), or (d) vehicle injections. The high MDMA dose regime and the amphetamine treatment both produced acute hyperactivity and hyperthermia. Twelve weeks later, all rats were tested in the drug-free state on a battery of anxiety tests (elevated plus maze, emergence and social interaction tests). A further 2 weeks later they were tested on a novel object recognition memory task. Rats previously given the neurotoxic dose of MDMA showed greater anxiety-like behaviour on all three anxiety tests relative to both controls and D-amphetamine-treated rats. Rats given the moderate MDMA dose regime also showed increased anxiety-like behaviour on all three tests, although to a lesser extent than rats in the high dose group. In the object recognition task, rats given the high MDMA dose regime showed impaired memory relative to all other groups when tested at a 15-min delay but not at a 60-min delay. Rats previously exposed to amphetamine did not differ from saline controls in the anxiety or memory tests. These data suggest that moderate to heavy MDMA exposure over 48 h may lead to increased anxiety and memory impairment 3 months later, possibly through a neurotoxic effect on brain serotonin systems.

Temporal Lobe Cortical Electrical Stimulation during the Encoding and Retrieval Phase Reduces False Memories

A recent study found that false memories were reduced by 36% when low frequency repetitive transcranial magnetic stimulation (rTMS) was applied to the left anterior temporal lobe after the encoding (study) phase. Here we were interested in the consequences on a false memory task of brain stimulation throughout the encoding and retrieval task phases. We used transcranial direct current stimulation (tDCS) because it has been shown to be a useful tool to enhance cognition. Specifically, we examined whether tDCS can induce changes in a task assessing false memories. Based on our preliminary results, three conditions of stimulation were chosen: anodal left/cathodal right anterior temporal lobe (ATL) stimulation (“bilateral stimulation”); anodal left ATL stimulation (with a large contralateral cathodal electrode – referred as “unilateral stimulation”) and sham stimulation. Our results showed that false memories were reduced significantly after the two active conditions (unilateral and bilateral stimulation) as compared with sham stimulation. There were no significant changes in veridical memories. Our findings show that false memories are reduced by 73% when anodal tDCS is applied to the anterior temporal lobes throughout the encoding and retrieval stages, suggesting a possible strategy for improving certain aspects of learning.

The Incubation Effect: Hatching a Solution?

Numerous anecdotal accounts exist of an incubation period promoting creativity and problem solving. This article examines whether incubation is an empirically verifiable phenomenon and the possible role therein of nonconscious processing. An Idea Generation Test was employed to examine (a) whether an incubation effect occurred and (b) the impact of different types of break on this effect. In the Idea Generation Test, two groups of participants were given a distracting break, during which they completed either a similar or an unrelated task, and a third group worked continuously (N = 90). The Idea Generation Test was validated against established measures of cognitive ability and personality, and was found to exhibit variance distinct from those marker tests. Most important, results demonstrated that having a break during which one works on a completely different task is more beneficial for idea production than working on a similar task or generating ideas continuously. The advantage afforded by a break cannot be accounted for in terms of relief from functional fixedness or general fatigue, and, although it may be explicable by relief from task-specific fatigue, explanations of an incubation effect in terms of nonconscious processing should be (re)considered.

Creative People Use Nonconscious Processes to Their Advantage

Although contentious, there is evidence to suggest that nonconscious processes contribute to creative output, particularly during refractory periods. However, no one has examined whether this break benefit differs as a function of creative ability. To address these issues, this investigation examined Wallass (1926) seminal theoretical framework of creativity. More specifically, the most controversial stage postulated by Wallas, the incubation phase, was empirically tested. A regression analysis demonstrated that productivity is significantly increased when creative people activate nonconscious processes in off-task or incubation periods. There is ongoing debate about the cause(s) of this incubation effect. This research provides evidence that the incubation effect results, at least partially, from nonconscious processing and that it provides greater benefit to more creative individuals. This suggests that highly creative people should be exposed to focus problems/challenges well in advance of objective deadlines, and have freedom to generate solutions outside of structured evaluation times.

Evidence for a social function of the anterior temporal lobes: Low-frequency rTMS reduces implicit gender stereotypes

By nature, stereotypes require processes of categorization or semantic association, including social information about groups of people. There is empirical evidence that the anterior temporal lobe (ATL) processes domain‐general semantic information, and supports social knowledge. A recent study showed that inhibitory repetitive transcranial magnetic stimulation (rTMS) to the ATL reduced racial stereotypes on an implicit association test (IAT). However, it was not determined whether this was caused by changes to specific social, or general semantic processing, or both. The current study addresses these theoretical issues. The design investigated the effect of rTMS to the left or right ATL, or a sham stimulation, on a social IAT (gender stereotypes), a non-social IAT (living versus non-living associations), and a non-semantic control (Stroop) task. The results showed that low-frequency rTMS to both left and right ATL significantly reduced D-scores on the gender IAT compared to the sham group; however, there were no differences on the non-social IAT or the Stroop. The findings show the ATL has a role in mediating stereotypes, and the decrease of bias after stimulation could be due to weakening of social stereotypical associations either within the ATL or via a network of brain regions connected with the ATL.

Low-frequency repetitive transcranial magnetic stimulation of the anterior temporal lobes does not dissociate social versus nonsocial semantic knowledge

Social conceptual knowledge is imperative to communicate with, interact with, and interpret human society; however, little is known about the neural basis of social concepts. Previous research has predominantly suggested that the right anterior temporal lobe (ATL) may specifically represent social conceptual knowledge, whereas the left ATL is necessary for general semantic processing. However, this view has not always been supported by empirical studies. Employing a lateralized design and two different semantic tasks and a nonsemantic control task, we aimed to clarify some of these ambiguities by potentially dissociating left from right functionality and social from nonsocial concepts, using inhibitory repetitive transcranial magnetic stimulation (rTMS) coupled with a sham and control site stimulation (N = 56). The results showed that stimulation of the left ATL led to overall faster processing times without affecting accuracy, whilst the right ATL and control groups did not significantly change in reaction times or accuracy. No difference occurred between social and nonsocial concepts after stimulation. This study is the first to show that inhibition of the left temporal lobe may improve performance on a semantic task and provides evidence that the ATLs may be lateralized in conceptual processing. The results do not confirm that the right temporal lobe is crucial for social conceptual processing, as inhibition did not significantly affect performance for social concepts.