The near win effect on observing behaviour in simulated slot-machine gambling: The role of conditioned reinforcement

<p>Slot machines are a remarkably popular mode of gambling even though they are programmed to make a profit by paying out less money than is put in. One common feature of slot machines, which may increase the likelihood of persistent gambling in the face of this monetary loss, is the near win. This study’s aim was to investigate the conditioned reinforcing properties of near wins using an observing response procedure in the context of a simulated slot machine. In an observing response procedure, participants can use an observing button to produce a stimulus correlated with the availability of reinforcement (S+) or a stimulus correlated with no reinforcement or less reinforcement (S-). The percentage of observing responses made for each stimulus is thought to reflect the reinforcing efficacy of the reinforcer correlated with each stimulus. Experiment 1 successfully tested the procedure with an obvious reinforcer - wins - and found consistently more observing for the S+. In Experiment 2 and 3 the S+ was correlated with near wins, and in Experiment 2 only those with slot-machine experience had consistently more observing for the S+. Experiment 3 increased the probability of wins to enhance the reinforcing efficacy of near wins, but failed to find consistently more observing for the S+, regardless of slot machine or scratchie card experience. These results indicated that near wins are not conditioned reinforcers. However, participants tended to bet more following near wins than losses, which suggested that near wins may instead function as discriminative stimuli.</p>

The near win effect on observing behaviour in simulated slot-machine gambling: The role of conditioned reinforcement

<p>Slot machines are a remarkably popular mode of gambling even though they are programmed to make a profit by paying out less money than is put in. One common feature of slot machines, which may increase the likelihood of persistent gambling in the face of this monetary loss, is the near win. This study’s aim was to investigate the conditioned reinforcing properties of near wins using an observing response procedure in the context of a simulated slot machine. In an observing response procedure, participants can use an observing button to produce a stimulus correlated with the availability of reinforcement (S+) or a stimulus correlated with no reinforcement or less reinforcement (S-). The percentage of observing responses made for each stimulus is thought to reflect the reinforcing efficacy of the reinforcer correlated with each stimulus. Experiment 1 successfully tested the procedure with an obvious reinforcer - wins - and found consistently more observing for the S+. In Experiment 2 and 3 the S+ was correlated with near wins, and in Experiment 2 only those with slot-machine experience had consistently more observing for the S+. Experiment 3 increased the probability of wins to enhance the reinforcing efficacy of near wins, but failed to find consistently more observing for the S+, regardless of slot machine or scratchie card experience. These results indicated that near wins are not conditioned reinforcers. However, participants tended to bet more following near wins than losses, which suggested that near wins may instead function as discriminative stimuli.</p>

Nicotine Self-Administration With Tobacco Flavor Additives in Male Rats

Introduction Nicotine can robustly increase responding for conditioned reinforcers (CRs), stimuli that acquire reinforcing properties based on association with primary reinforcers. Menthol and licorice are tobacco flavoring agents also found in sweet foods (eg, candy and ice cream), making them putative CRs before they are consumed in tobacco. We sought to determine if intravenous self-administration (IVSA) of nicotine was enhanced by the inclusion of oral tobacco flavor CRs. Methods Menthol (160 or 320 µM) or licorice root extract (0.1% or 1%) were established as CRs (paired with 20% sucrose) or “neutral” stimuli (paired with water) in separate groups. During subsequent IVSA tests, nicotine was delivered in conjunction with oral presentations of the CR. Results In experiment 1, a menthol CR significantly shifted the peak nicotine dose from 15 µg/kg/infusion (Neutral group) to 3.25 µg/kg/infusion (CR group). In experiment 2, a menthol CR significantly increased operant licks for nicotine (3 µg/kg/infusion) relative to control groups. In experiment 3, both licorice and menthol CRs significantly increased operant licks for nicotine (7.5 µg/kg/infusion) relative to an “inactive” sipper. The licorice CR increased nicotine IVSA in proportion to the strength of the flavor, but both menthol concentrations increased nicotine IVSA to a similar extent. Conclusion Tobacco flavor additives with conditioned reinforcing properties promote acquisition of nicotine self-administration at low unit doses and may have robust impact on tobacco consumption when nicotine yield is low. Implications Tobacco flavor additives are found in rewarding foods (eg, ice cream) and gain palatability based on associations with primary rewards (eg, sugar) making them “conditioned reinforcers.” Nicotine increases the motivation for flavor conditioned reinforcers and the present studies show that tobacco flavor additives can interact with nicotine to promote more nicotine self-administration. The interaction between flavors additives and nicotine may promote nicotine exposure and subsequently dependence.

α4-containing GABAA receptors on dopamine D2 receptor-expressing neurons mediate instrumental responding for conditioned reinforcers, and its potentiation by cocaine

Extrasynaptic GABAA receptors (GABAARs) composed of α4, β and δ subunits mediate GABAergic tonic inhibition and are pertinent molecular targets in the modulation of behavioural responses to drugs of abuse, including ethanol and cocaine. These GABAARs are highly expressed within the nucleus accumbens (NAc) where they influence the excitability of the medium spiny neurons (MSNs). Here we explore their role in modulating behavioural responses to reward-conditioned cues and the behaviour-potentiating effects of cocaine. α4-subunit constitutive knockout mice (α4-/-) showed higher rates of instrumental responding for reward-paired stimuli in a test of conditioned reinforcement (CRf). A similar effect was seen following viral knockdown of GABAAR α4 subunits within the NAc. Local infusion of the δ-GABAAR-preferring agonist, THIP, into the NAc had no effect on responding when given alone, but reduced cocaine potentiation of responding for conditioned reinforcers in wildtype but not α4-/- mice. Finally, specific deletion of α4-subunits from dopamine D2-, but not D1-receptor-expressing neurons, mimicked the phenotype of the constitutive knockout, potentiating CRf responding and blocking intra-accumbal THIP attenuation of cocaine-potentiated CRf responding. These data demonstrate that α4-GABAAR mediated inhibition of dopamine D2 receptor-expressing neurons reduces instrumental-responding for a conditioned reinforcer, and its potentiation by cocaine, and emphasise the potential importance of GABAergic signalling within the NAc in mediating cocaine’s effects.