Motivational Properties Research Articles

Development and Psychometric Assessment of the Social Media Motives Scale among University Students

<p style="text-align:justify">Social media (SM) use is a rapidly growing phenomenon among Millennials. Thus, a growing body of studies have explored the beneficial applications and negative consequences of their use in an increasingly virtual world. The current study aimed to develop and validate a scale that measures university students’ motives for using SM from a psychological and social perspective. In Study 1 (N = 316), the psychometric properties of SM motives were examined. The estimated factorial structure was validated in Study 2 (N = 200). The Study 1 results showed two active personal motives scales (i.e., self-actualization and purposive motives), one passive motive scale (i.e., enjoyment), one active contextual motive scale (i.e., self-enhancement), and a contextual (neither active nor passive) motive scale (i.e., a factor of convenience). Study 2 findings confirmed this factorial structure. Construct validity was supported with significant differences between three types of users (i.e., productive, consuming, and disinterested) on their motives (151 words).</p>

Time‐of‐Day Variation in Learning, Reward‐Associated Behaviors, and in Rapid Dopamine Signaling

Approximately one in five adults in the United States suffers from at least one psychiatric disorder. Research has shown that biological rhythms in physiology and behavior play a role in a number of psychiatric disorders, like depression and substance use disorder (SUD). For example, time‐of‐day variation has been observed in craving for nicotine, heroin, and cocaine in abstinent individuals. However, we have yet to fully delineate how these rhythms mediate variations in motivated behavior, learning, and reward seeking. This is critical as aberrant motivation and learning are hallmarks in these disorders. The mesolimbic dopamine (DA) system is implicated in the neurobiology of motivation and learning, and research has shown time‐of‐day variations in DA tone. Less work has focused on rapid DA signals that are critical for motivation and learning. Thus, the purpose of this study was to examine time‐of‐day variations in incentive motivational properties of reward‐associated cues and learning and the degree to which the magnitude of mesolimbic DA release in the nucleus accumbens (NAc) corresponded to dynamic shifts in motivation and learning across time‐of‐day. Our central hypothesis is that there are critical times within the day that confer increased sensitivity to reward‐associated cues, which are mediated by time‐of‐day variations in the magnitude of phasic DA signaling. To test this hypothesis, we examined the magnitude of NAc DA signaling to stimulations that mimic both tonic and phasic firing of mesolimbic DA neurons in rats. We used ex vivo fast scan cyclic voltammetry (FSCV) at four different time points across the 12:12 light/dark cycle. Our data demonstrate robust time‐of‐day differences in DA release magnitude following stimulations that model both phasic (≥20 Hz) and tonic (5 Hz) firing. Given that the phasic/tonic ratio of DA release magnitude was greatest midway through the dark cycle and lowest midway through the light cycle, we examined whether behavioral paradigms sensitive to DA release magnitude would fluctuate consistently with these DA oscillations. We therefore utilized Pavlovian paradigms in rodents to measure incentive motivational aspects and conditioned approach towards a reward‐associated cue, during midway through the light cycle and midway through the dark cycle. Furthermore, since DA release and motivated behavior is modulated by striatal cholinergic interneuron (CIN) activity via nicotinic receptors (nAChRs) located on DA axons, we examined whether both DA release and incentive motivation was altered following nicotine exposure. Lastly, we utilized optogenetics to unmask the circuitry underlying these diurnal variations. Our current data suggest that rats midway through their dark cycle exhibit increased sensitivity to reward‐associated cues, which may be mediated by rapid DA release that is modulated by oscillations in CIN activity. These novel data support that there are be times within the day in which an individual may be more vulnerable to reward‐associated cues, which may correspond to variations in rapid DA signaling mediated by CIN oscillations throughout the day.Support or Funding InformationK99/R00 DA031791P50 DA006634P50 AA026117Peter F. McManus Charitable Trust

The Effect of Narrative on Physical Activity via Immersion During Active Video Game Play in Children: Mediation Analysis.

BackgroundActive video games (AVGs) can increase physical activity (PA) and help produce higher physiological expenditure. Animated narrative videos (NVs) possess unique immersive and motivational properties. When added to AVGs, they have been found to increase moderate-to-vigorous physical activity (MVPA) as opposed to the original no video condition. However, there is no evidence of whether that was due to the NV or the addition of an animated video to an AVG.ObjectiveThis study aimed to investigate the differential effect of adding an NV versus a nonnarrative video (NNV) to an AVG on PA parameters and physiological responses and to explore the mediating role of immersion.MethodsA total of 22 children aged 8 to 12 years were randomly assigned to the NV or NNV condition. They were instructed to play an AVG (on Xbox Kinect) for as long as they wanted. We used accelerometers to estimate the time spent (in minutes) in MVPA. Heart rate (HR) and rate of perceived exertion (RPE) were measured before, during, and after the AVG play session. The participants then reported their experience of narrative immersion via a questionnaire.ResultsThe NV group had significantly higher narrative immersion (mean 3.50, SD 0.55 vs mean 2.91, SD 0.59; P=.03) and MVPA (mean 19.46, SD 13.31 vs mean 7.85, SD 5.83; P=.02) than the NNV group. Narrative immersion was positively correlated with MVPA (r=0.52; P=.01) and average HR during AVG (r=0.43; P=.05). Mediation analysis indicated that narrative immersion mediated the effect of NV (NV vs NNV) on MVPA (direct effect: beta=7.51; P=.01). The indirect effect was that NV was positively correlated with the mediator variable narrative immersion (beta=.59; P=.03), which was itself marginally associated with MVPA (beta=6.95; P=.09); when narrative immersion was included in the model, the regression coefficient was attenuated.ConclusionsAVG with added narratives elicits more narrative immersion, resulting in more minutes in MVPA. Narrative immersion served as a mediator between NV and MVPA via its elicitation of an elevated HR without increasing RPE. The inclusion of immersive narratives in AVG could be helpful for inducing MVPA, to enhance AVG engagement without additional exertion.

Fetal Alcohol Programming of Subsequent Alcohol Affinity: A Review Based on Preclinical, Clinical and Epidemiological Studies.

The anatomo-physiological disruptions inherent to different categories of the Fetal Alcohol Spectrum Disorder do not encompass all the negative consequences derived from intrauterine ethanol (EtOH) exposure. Preclinical, clinical and epidemiological studies show that prenatal EtOH exposure also results in early programming of alcohol affinity. This affinity has been addressed through the examination of how EtOH prenatally exposed organisms recognize and prefer the drug’s chemosensory cues and their predisposition to exhibit heightened voluntary EtOH intake during infancy and adolescence. In altricial species these processes are determined by the interaction of at least three factors during stages equivalent to the 2nd and 3rd human gestational trimester: (i) fetal processing of the drug’s olfactory and gustatory attributes present in the prenatal milieu; (ii) EtOH’s recruitment of central reinforcing effects that also imply progressive sensitization to the drug’s motivational properties; and (iii) an associative learning process involving the prior two factors. This Pavlovian learning phenomenon is dependent upon the recruitment of the opioid system and studies also indicate a significant role of EtOH’s principal metabolite (acetaldehyde, ACD) which is rapidly generated in the brain via the catalase system. The central and rapid accumulation of this metabolite represents a major factor involved in the process of fetal alcohol programming. According to recent investigations, it appears that ACD exerts early positive reinforcing consequences and antianxiety effects (negative reinforcement). Finally, this review also acknowledges human clinical and epidemiological studies indicating that moderate and binge-like drinking episodes during gestation result in neonatal recognition of EtOH’s chemosensory properties coupled with a preference towards these cues. As a whole, the studies under discussion emphasize the notion that even subteratogenic EtOH exposure during fetal life seizes early functional sensory and learning capabilities that pathologically shape subsequent physiological and behavioral reactivity towards the drug.

Dose-dependent induction of CPP or CPA by intra-pVTA ethanol: Role of mu opioid receptors and effects on NMDA receptors

The neurobiological mechanisms underlying alcohol motivational properties are still not fully understood, however, the mu-opioid receptors (MORs) have been evidenced as central elements in the manifestation of the alcohol reinforcing properties. Drug-associated environmental stimuli can trigger alcohol relapse and promote alcohol consumption whereby N-methyl-d-aspartate (NMDA) receptors play a pivotal role. Here we sought to demonstrate, for the first time, that ethanol induces conditioned place preference or aversion (CPP or CPA) when administered locally into the ventral tegmental area (VTA) and the associated role of MORs. We further analyzed the changes in the expression and mRNA levels of GluN1 and GluN2A subunits in designated brain areas. The expression of CPP or CPA was characterized following intra-VTA ethanol administration and we showed that either reinforcing (CPP) or aversive (CPA) properties are dependent on the dose administered (ranging here from 35 to 300 nmol). Furthermore, the critical contribution of local MORs in the acquisition of CPP was revealed by a selective antagonist, namely β-Funaltrexamine. Finally, modifications of the expression of NMDA receptor subunits in the Nucleus Accumbens (NAc) and Hippocampus after ethanol-induced CPP were analyzed at the proteomic and transcriptomic levels by western blot and In Situ Hybridation RNAscope techniques, respectively. Results showed that the mRNA levels of GluN2A but not GluN1 in NAc are higher after ethanol CPP. These novel results pave the way for further characterisation of the mechanisms by which ethanol motivational properties are associated with learned environmental cues.

Treatment with low doses of nicotine but not alcohol affects social play reward in rats

ABSTRACTSocial play behaviour is a vigorous, highly rewarding activity in young animals. It is thought to facilitate social, cognitive and emotional development, but its underlying neural mechanisms are incompletely understood. Previously, we found that low doses of alcohol and nicotine enhanced social play behaviour in young rats. Using place and operant conditioning setups to assess the pleasurable and motivational aspects of social play, we investigated how treatment with nicotine and alcohol affects social play reward. Nicotine-treatment increased the incentive motivational properties of social play as well as the expression of social play itself. Moreover, while nicotine by itself evoked conditioned place preference (CPP), it reduced social play-induced CPP. Alcohol-treatment did not affect the motivation for and expression of social play, nor did it affect social play-induced CPP. The finding that nicotine but not alcohol modulates social play reward increases our understanding of the neural underpinnings of this developmentally important behaviour.

A Review of the Prevalence of Psychosis in Sexual Homicide.

Despite a growing body of research on the association between psychosis and homicide and between psychosis and sexual offending, research on psychosis and sexual homicide is limited. The objective of this review was to estimate the prevalence of psychosis in sexual homicide and to explore the extent to which prior research has investigated symptoms of psychosis as a motivating or causal variable leading to incidents of sexual homicide. We hypothesized that psychosis is present in a minority of sexual homicide cases. Articles were identified by searching literature databases (i.e., PsycINFO, MEDLINE, EMBASE) and references of relevant articles. Eight studies were included. The overall prevalence of psychosis among individuals who committed sexual homicide ranged from 0 to 27 percent as measured in a broad array of diverse samples. Given that five of the eight studies reported psychosis rates to be five percent or less, our findings suggest that psychosis occurs in a minority of sexual homicide cases. None of the studies directly examined the causal or motivational properties of psychosis in driving these types of offenses, and this represents an important area of inquiry for future research.

From brands to classical music: Broadening and deepening a brand love prototype

Love is complex phenomenon, purportedly universal with powerful motivational properties. Love objects vary, and in the consumer marketing domain brand love has received considerable attention. We broaden theory by revising a brand love prototype and applying it in a non-brand context, and we deepen theory by examining the relationship between core brand love elements and loyalty at different levels of past behaviour. Our findings show that the revised model provides an excellent representation of the data and explains 53% of the variance in loyalty for classical music concerts and we confirm that past behaviour significantly modifies the relationships between constructs in the model.

The novel MAGL inhibitor MJN110 enhances responding to reward-predictive incentive cues by activation of CB1 receptors

CB1 receptor antagonists disrupt operant responding for food and drug reinforcers, and cue-induced reinstatement of cocaine and heroin seeking. Conversely, enhancing endocannabinoid signaling, particularly 2-arachidonyl glycerol (2-AG), by inhibition of monoacyl glycerol lipase (MAGL), may facilitate some aspects of reward seeking. To determine how endocannabinoid signaling affects responding to reward-predictive cues, we employed an operant task that allows us to parse the incentive motivational properties of cues. Rats were required to nosepoke during an intermittent audiovisual incentive cue (IC) to obtain a 10% sucrose reward. The CB1 receptor antagonist, rimonabant, dose-dependently decreased the response ratio (rewarded ICs/total presented) and active nosepokes per IC, while it increased the latency to respond to the cue and obtain the reward, indicating an overall decrease in both the choice and vigor of responding. Yet rats persisted in entering the reward cup. Using a modified version of the task, the novel MAGL inhibitor MJN110 increased the response ratio, decreased the latencies to respond to the IC and enhanced active nosepokes per IC, indicating a facilitation of cue-induced reward seeking. These effects were blocked by a subthreshold dose of rimonabant. Finally, MJN110 did not alter consumption of freely available sucrose within volumes obtained in the operant task. Together these data demonstrate blocking endocannabinoid tone at the CB1 receptor attenuates the ability of cues to induce reward seeking, while some aspects of motivation for the reward are retained. Conversely, enhancing 2-AG signaling at CB1 receptors facilitates IC responding and increases the motivational properties of the IC.

Voluntary exercise is motivated by ghrelin, possibly related to the central reward circuit.

We previously reported that voluntary exercise contributed to the amelioration of abnormal feeding behavior with a concomitant restoration of ghrelin production in a rat model of obesity, suggesting a possible relationship between exercise and appetite-regulating hormones. Ghrelin is known to be involved in the brain reward circuits via dopamine neurons related to motivational properties. We investigated the relevance of ghrelin as an initiator of voluntary exercise as well as feeding behavior. The plasma ghrelin concentration fluctuates throughout the day with its peak at the beginning of the dark period in the wild-type (WT) mice with voluntary exercise. Although predominant increases in wheel running activity were observed accordant to the peak of plasma ghrelin concentration in the WT mice, those were severely attenuated in the ghrelin-knockout (GKO) mice under either ad libitum or time-restricted feeding. A single injection of ghrelin receptor agonist brought about and reproduced a marked enhancement of wheel running activity, in contrast to no effect by the continuous administration of the same drug. Brain dopamine levels (DAs) were enhanced after food consumption in the WT mice under voluntary exercise. Although the acceleration of DAs were apparently blunted in the GKO mice, they were dramatically revived after the administration of ghrelin receptor agonist, suggesting the relevance of ghrelin in the reward circuit under voluntary exercise. These findings emphasize that the surge of ghrelin plays a crucial role in the formation of motivation for the initiation of voluntary exercise possibly related to the central dopamine system.

‘It’s like having a test but in a fun way’

Abstract Assessment is a central challenge within classroom-based early language learning, where there is a need to employ assessment methods which, as well as being valid and reliable for a range of learners, protect rather than diminish motivation. The motivational properties of digital or serious games within language learning are increasingly recognised in the literature, yet the value of digital game-based assessment (DGBA) remains underexplored. This study used a questionnaire to examine how 3437 young language learners of English, Spanish, German, Italian and French perceived a DGBA tool and the extent to which their perceptions were modulated by age, gender and performance levels on the game. Learners perceived the DGBA tool as fun to play, worth playing again, helpful for telling them about their progress and of moderate difficulty level. Girls were more positive than boys about the game but for all learners levels of positivity were not related to age. There was a significant but weak relationship between positivity and game scores, suggesting that learners liked the game regardless of their attainment levels. The study’s findings are discussed in relation to theories of motivation associated with digital game-based tools and their practical implications for the teaching of early language learners.

Inhibition of Morphine- and Ethanol-Mediated Stimulation of Mesolimbic Dopamine Neurons by Withania somnifera.

Morphine- and ethanol-induced stimulation of neuronal firing of ventral tegmental area (VTA) dopaminergic neurons and of dopamine (DA) transmission in the shell of the nucleus accumbens (AcbSh) represents a crucial electrophysiological and neurochemical response underlying the ability of these compounds to elicit motivated behaviors and trigger a cascade of plasticity-related biochemical events. Previous studies indicate that the standardized methanolic extract of Withania somnifera roots (WSE) prevents morphine- and ethanol-elicited conditioned place preference and oral ethanol self-administration. Aim of the present research was to investigate whether WSE may also interfere with the ability of morphine and ethanol to stimulate VTA dopaminergic neurons and thus AcbSh DA transmission as assessed in male Sprague-Dawley rats by means of patch-clamp recordings in mesencephalic slices and in vivo brain microdialysis, respectively. Morphine and ethanol significantly stimulated spontaneous firing rate of VTA neurons and DA transmission in the AcbSh. WSE, at concentrations (200–400 μg/ml) that significantly reduce spontaneous neuronal firing of VTA DA neurons via a GABAA- but not GABAB-mediated mechanism, suppressed the stimulatory actions of both morphine and ethanol. Moreover, in vivo administration of WSE at a dose (75 mg/kg) that fails to affect basal DA transmission, significantly prevented both morphine- and ethanol-elicited increases of DA in the AcbSh. Overall, these results highlight the ability of WSE to interfere with morphine- and ethanol-mediated central effects and suggest a mechanistic interpretation of the efficacy of this extract to prevent the motivational properties of these compounds.

881-P: Patient and Clinician Usability Rating of Commercially Available Diabetes Apps

Background: Despite the significant clinical benefit in hemoglobin A1c reduction, diabetes applications (apps) use is low. The goal of this study was to assess app usability based on the heuristics of intuitive designs and the Theory of Self-Determination on motivation. Diabetes apps were evaluated by clinicians and patients for motivational properties that target patient needs to learn blood glucose trends and patterns (competence), to personalize choices to change (autonomy) and to connect with healthcare providers (feel related). Method: Two top-rated Android apps, mySugr and OnTrack, underwent evaluation by four clinicians (three physicians and one diabetes nurse educator) and 92 adults with type 1 or 2 diabetes on insulin. Each app was tested for seven diabetes-related tasks including data entry, analysis, report view options (by the day of the week and by meals), and report email. Clinicians evaluated if the app violated Nielsen's Ten Heuristics on user-friendly designs. Both clinicians and patients completed a questionnaire on the ease of use - System Usability Scale (SUS). Results: OnTrack and mySugr target two behavior needs important for motivation in diabetes self-management. App usability was suboptimal to low. Clinicians rated an “F” for mySugr (15 ± 5) scoring < 60 and a “D” for OnTrack (61 ± 28) scoring between 60-69. Patients rated an “F” for mySugr (55 ±18) and a “D” for OnTrack (68 ±15). Clinicians identified many heuristic violations (n=169): mySugr (90) and OnTrack (77). Heuristic principles violated the most frequently were “Help and Documentation” (38), followed by “Aesthetic and Minimalist Design” (43) and “Error Prevention” (24). Conclusions: Commercially available diabetes app usability was marginally acceptable to unacceptable according to clinicians and patients. Future diabetes app design needs to target patient motivation and incorporate key heuristic principles to provide self-tutorials, enhance graphical or screen views, and eliminate error-prone conditions. Disclosure H.N. Fu: None. T. Adam: Stock/Shareholder; Self; GlaxoSmithKline plc. J.F. Wyman: None. Funding Robert Wood Johnson Foundation; Sigma Theta Tau International-Zeta Chapter

How does exercise support dietary approaches to weight loss and better health?

The rapid global rise of obesity incurs a heavy personal and healthcare burden due to obesity-associated morbidities and shortening of life. The purpose of this review is to provide evidence-based strategies for prevention, reversal, and mitigation of obesity and its sequelae. To that end, this review highlights the features of human physiology that favor fat accretion and interfere with fat loss. Strategies for prevention of obesity include understanding the basis for the strong motivating properties of palatable food, for human inability to consciously detect calories eaten or calories expended through exercise, for metabolic and hormonal adaptations to negative energy balance that drive weight regain, and for evolutionary natural selection which likely led to high human capacity for fat storage. Reversal of obesity is difficult primarily due to metabolic, hormonal, and behavioral reactions to body fat loss. Reduced resting metabolic rate presents a physiological challenge whether the weight loss is achieved through dietary restriction or energy expenditure of exercise. Increased insulin sensitivity after body fat loss drives resynthesis of storage substrates including triglycerides in the adipose tissue, muscle glycogen, and proteins, thus contributing to weight regain. Reduced basal plasma leptin concentration elicits a strong hunger drive. Mitigation of obesity-associated morbidities involves adding exercise energy expenditure to deliberate control of the quantity of food eaten, reducing postprandial hyperinsulinemia by lowering the carbohydrate load of the diet, and exercising after, rather than before, the meals to facilitate improved glucose tolerance.

Nicotine Produces a High-Approach, Low-Avoidance Phenotype in Response to Alcohol-Associated Cues in Male Rats.

Nicotine and alcohol use are highly comorbid. Modulation of drug-paired extrinsic and intrinsic cues likely plays a role in this interaction, as cues can acquire motivational properties and augment drug seeking. The motivational properties of cues can be measured through Pavlovian conditioning paradigms, in which cues either elicit approach following pairing with the reinforcing properties of alcohol or elicit avoidance following pairing with the aversive consequences of alcohol. The present experiments tested whether nicotine would enhance the incentive properties of an appetitive ethanol (EtOH) cue and diminish the avoidance of an aversive EtOH cue in Pavlovian paradigms. In experiment 1, male Long-Evans rats with or without prior chronic intermittent access to EtOH were administered nicotine or saline injections prior to Pavlovian conditioned approach (PavCA) sessions, during which conditioned approach to the cue ("sign-tracking") or the EtOH delivery location ("goal-tracking") was measured. In experiment 2, male Long-Evans rats were administered nicotine or saline injections prior to pairing a flavor cue with increasing doses of EtOH (i.p.) in an adaptation of the conditioned taste avoidance (CTA) paradigm. Results from PavCA indicate that, regardless of EtOH exposure, nicotine enhanced responding elicited by EtOH-paired cues with no effect on a similar cue not explicitly paired with EtOH. Furthermore, nicotine reduced sensitivity to EtOH-induced CTA, as indicated by a rightward shift in the dose-response curve of passively administered EtOH. The ED50 , or the dose of EtOH that produced a 50% reduction in intake relative to baseline, was significantly higher in nicotine-treated rats compared to saline-treated rats. We conclude that nicotine increases the approach and diminishes the avoidance elicited by Pavlovian cues paired, respectively, with the reinforcing and aversive properties of EtOH consumption in male rats. As such, nicotine may enhance alcoholism liability by engendering an attentional bias toward cues that predict the reinforcing outcomes of drinking.

Self-regulated learning lens on trainee perceptions of the mini-CEX: a qualitative study

ObjectivesThe formative aspect of the mini-clinical evaluation exercise (mini-CEX) in postgraduate medical workplace-based assessment is intended to afford opportunities for active learning. Yet, there is little understanding of the perceived...

Knowledge about the predictive value of reward conditioned stimuli modulates their interference with cognitive processes.

Stimuli conditioned with a substance can generate drug-approach behaviors due to their acquired motivational properties. According to implicit theories of addiction, these stimuli can decrease cognitive control automatically. The present study (n = 49) examined whether reward-associated stimuli can interfere with cognitive processes in the absence of knowledge about stimulus–outcome contingencies. Conditioned stimuli (CS) were paired with high-reward (HR) or low-reward (LR) probabilities of monetary reward using a Pavlovian learning task. Participants were categorized as Aware or Unaware of contingencies using a Bayesian analysis. CS were then used as task-irrelevant distractors in modified flanker and N-back tasks. Results show HR CS can generate increased interference in the flanker task for participants Unaware of contingencies, contributing further evidence for the existence of implicit Pavlovian conditioning. For the N-back task, working memory performance was affected by HR CS, albeit only for Aware participants. These results suggest that CS can interfere implicitly with cognitive processes in a similar way to drug-related stimuli. Such an effect could occur in a stimulus-driven fashion, devoid of top-down goal-directedness. These findings have implications for the conceptualization and study of implicit processes in addiction and highlights the necessity to reconsider the measurement of such phenomena.

Limbic control over the homeostatic need for sodium

The homeostatic need for sodium is one of the strongest motivational drives known in animals. Although the brain regions involved in the sensory detection of sodium levels have been mapped relatively well, data about the neural basis of the motivational properties of salt appetite, including a role for midbrain dopamine cells, have been inconclusive. Here, we employed a combination of fiber photometry, behavioral pharmacology and c-Fos immunohistochemistry to study the involvement of the mesocorticolimbic dopamine system in salt appetite in rats. We observed that sodium deficiency affected the responses of dopaminergic midbrain neurons to salt tasting, suggesting that these neurons encode appetitive properties of sodium. We further observed a significant reduction in the consumption of salt after pharmacological inactivation of the nucleus accumbens (but not the medial prefrontal cortex), and microstructure analysis of licking behavior suggested that this was due to decreased motivation for, but not appreciation of salt. However, this was not dependent on dopaminergic neurotransmission in that area, as infusion of a dopamine receptor antagonist into the nucleus accumbens did not alter salt appetite. We conclude that the nucleus accumbens, but not medial prefrontal cortex, is important for the behavioral expression of salt appetite by mediating its motivational component, but that the switch in salt appreciation after sodium depletion, although detected by midbrain dopamine neurons, must arise from other areas.

Cues play a critical role in estrous cycle-dependent enhancement of cocaine reinforcement.

While preclinical work has aimed to outline the neural mechanisms of drug addiction, it has overwhelmingly focused on male subjects. There has been a push in recent years to incorporate females into existing addiction models; however, males and females often have different behavioral strategies, making it important to not only include females, but to develop models that assess the factors that comprise female drug addiction. Traditional self-administration models often include light or tone cues that serve as discriminative stimuli and/or consequent stimuli, making it nearly impossible to disentangle the effects of cue learning, the cues themselves, and acute effects of psychostimulant drugs. To disentangle the interaction between drug-associated cues and the consummatory and appetitive responding driven by cocaine, we have developed a new behavioral procedure that combines Pavlovian-instrumental transfer with behavioral economic analysis. This task can be completed within a single session, allowing for studies looking at estrous cycle stage-dependent effects in intact cycling females, something that has been difficult in the past. In this study, we found no differences in self-administration across the estrous cycle in the absence of cues; however, when cues were introduced, the cues that acquired value during estrus-but not during diestrus or in males-increased motivation. Cues paired during estrus also increased c-fos expression to a greater extent in striatal regions, an effect that may underlie the observed increases in seeking induced by these cues, even weeks later. Together, these data suggest that fundamental differences in the motivational properties of psychostimulant drugs between males and females are complex and are driven primarily by the interaction between drug-associated stimuli and drug effects.

Sigma-1 receptor antagonist PD144418 suppresses food reinforced operant responding in rats

Sigma-1 (σ1) receptors have been investigated for their involvement in learning, rewarding and motivational processes, particularly as it relates to substances of abuse. Few studies have examined the effects of σ1 receptor agonists and antagonists on the rewarding and motivational properties of natural reinforcers, such as food. Studies that have investigated σ1 receptor agonists and antagonists has produced conflicting results. σ1 receptor antagonist PD144418 has been found to produce a dose-dependent attenuation of locomotor activity induced by cocaine, and by itself, does not suppress basal locomotor activity in mice. However, its effects on reward and motivation as it relates to food are unknown. The present study examined the involvement of σ1 receptors in mediating the rewarding and motivational properties of food using an operant task. The results indicated that at the highest dose (10 μmol/kg), PD144418 significantly attenuated the number of active lever responses for chow pellets but did not decrease the number of active lever responses for sucrose pellets under a fixed ratio (FR2) schedule of reinforcement. However, under a progressive ratio (PR) reinforcement schedule, 10 μmol/kg of PD14418 significantly reduced the breakpoint, a measure indicative of effort or motivation, for both chow and sucrose pellets. When ad libitum chow or sucrose pellets were made freely available (i.e. no lever press required) inside the operant chamber, 10 μmol/kg, PD144418 did not have an effect on number of pellets consumed. These findings indicate that PD144418 reduces the motivational effort of a food reinforced behavior.