Ethanol seeking triggered by environmental context is attenuated by blocking dopamine D1 receptors in the nucleus accumbens core and shell in rats

Conditioned behavioral responses to discrete drug-associated cues can be modulated by the environmental context in which those cues are experienced, a process that may facilitate relapse in humans. Rodent models of drug self-administration have been adapted to reveal the capacity of contexts to trigger drug seeking, thereby enabling neurobiological investigations of this effect. We tested the hypothesis that dopamine transmission in the nucleus accumbens, a neural structure that mediates reinforcement, is necessary for context-induced reinstatement of responding for ethanol-associated cues. Rats pressed one lever (active) for oral ethanol (0.1 ml; 10% v/v) in operant conditioning chambers distinguished by specific visual, olfactory, and tactile contextual stimuli. Ethanol delivery was paired with a discrete (4 s) light-noise stimulus. Responses on a second lever (inactive) were not reinforced. Behavior was then extinguished by withholding ethanol but not the discrete stimulus in a different context. Reinstatement, expressed as elevated responding for the discrete stimulus without ethanol delivery, was tested by placing rats into the prior self-administration context after administration of saline or the dopamine D1 receptor antagonist, SCH 23390 (0.006, 0.06, and 0.6 μg/side), into the nucleus accumbens core or shell. Compared with extinction responding, active lever pressing in saline-pretreated rats was enhanced by placement into the prior ethanol self-administration context. SCH 23390 dose-dependently reduced reinstatement after infusion into the core or shell. These findings suggest a critical role for dopamine acting via D1 receptors in the nucleus accumbens in the reinstatement of responding for ethanol cues triggered by placement into an ethanol-associated context

Perceived managerial and leadership effectiveness in a Korean context: An indigenous qualitative study

Multinational corporations (MNCs) across the world have sent an increasing number of managers abroad to leverage unprecedented opportunities in the era of globalization. However, their failure rate has been above 33% for decades, resulting in substantial costs (Puck, Kittler, & Wright, 2008). One of the primary reasons for this failure is a lack of understanding of the national and organizational cultures within the host countries (Festing & Maletzky, 2011). For example, while a number of MNCs have entered the Korean market, several such as Yahoo, Motorola, and Walmart have failed and withdrawn due to the companies’ lack of adjustment to the Korean cultural context (Choe, 2006; Woo, 2013). In spite of the significance of culturally embedded practices, most researchers who have explored management and leadership in Asian countries, whether they were Western or indigenous researchers, have implemented studies using extant Western management and leadership theories derived within the Western cultural context (Leung, 2007; Tsui, 2006). Numerous scholars have claimed that this could be problematic because the findings of such studies may not be applicable to non-Western countries (Li, 2012; Liden & Antonakis, 2009), and may fail to provide insights and understanding of novel contexts or to reveal indigenous aspects of management and leadership (Tsui, 2007). Consequently, there have been increasing calls for indigenous management and leadership research within Asian countries (see Li et al., 2014; Lyles, 2009; Tsui, 2004; Wolfgramm, Spiller, & Voyageur, 2014). Over the past 30 years, managerial effectiveness and leadership effectiveness have been substantially neglected areas of management research (Noordegraaf & Stewart, 2000; Yukl, Gordon, & Taber, 2002). In addition, there has been little agreement on what specific behaviors distinguish effective managers from ineffective ones. Furthermore, more research is needed to examine the managerial and leadership behaviors that are critical for shaping the performance of individuals, groups and organizations (see Borman & Brush, 1993; Cammock, Nilakant & Dakin, 1995; Mumford, 2011; Noordegraaf & Stewart, 2000; Yukl et al., 2002). While most of the research related to managerial and leadership effectiveness has been conducted in the U.S., the few notable non-U.S. studies include that of Cammock et al. (1995) in New Zealand who developed a behavioral lay model of managerial effectiveness using the repertory grid technique. Another notable exception is the cumulative series of perceived managerial and leadership effectiveness studies conducted by Hamlin with various indigenous co-researchers in Western and non-Western countries (see Hamlin & Patel, 2012; Ruiz, Wang, & Hamlin, 2013) using Flanagan’s (1954) critical incident technique (CIT)

Separable Roles of the Nucleus Accumbens Core and Shell in Context- and Cue-Induced Alcohol-Seeking

Conditioned responding to drug-predictive discrete cues can be strongly modulated by drug-associated contexts. We tested the hypothesis that differential recruitment of the nucleus accumbens (NAc) core and shell mediates responding to drug cues in a drug vs non-drug context. Rats were trained to discriminate between two 10-s auditory stimuli: one stimulus (CS+) was paired with ethanol (10% v/v; 0.2 ml; oral) whereas the other (CS−) was not. Training occurred in operant conditioning chambers distinguished by contextual stimuli, and resulted in increased entries into the ethanol delivery port during the CS+ when compared with the CS−. In experiment 1, port entries were then extinguished in a second context by withholding ethanol, after which context-induced renewal of ethanol-seeking was tested by presenting both stimuli without ethanol in the previous training context. This manipulation stimulated strong responding to the CS+ in rats pretreated with saline in the core (n=9) or shell (n=10), which was attenuated by pharmacologically inactivating (muscimol/baclofen; 0.1/1.0 mM; 0.3 μl/side) either subregion pretest. In experiment 2, after discrimination, training rats were habituated to a different context in which ethanol and both stimuli were withheld. Cue-induced ethanol-seeking was then elicited by presenting the CS+ and CS− without ethanol in the different context. Saline-pretreated rats responded more to the CS+ than the CS− (core n=8; shell n=9), and inactivating the core but not shell attenuated this effect. These data highlight an important role for the core in cue-induced ethanol-seeking, and suggest that the shell is required to mediate the influence of contexts on conditioned ethanol-seeking

Loss of Alternative Non-Drug Reinforcement Induces Relapse of Cocaine-Seeking in Rats: Role of Dopamine D1 Receptors

Animal models of relapse to drug seeking have focused primarily on relapse induced by exposure to drugs, drug-associated cues or contexts, and foot-shock stress. However, relapse in human drug abusers is often precipitated by loss of alternative non-drug reinforcement. The present experiment used a novel ‘resurgence' paradigm to examine relapse to cocaine seeking of rats as a result of loss of an alternative source of non-drug reinforcement. Rats were first trained to press a lever for intravenous infusions of cocaine. Next, cocaine deliveries were omitted and food pellets were provided for an alternative nose-poke response. Once cocaine seeking was reduced to low levels, food pellets for the alternative response were also omitted. Cocaine seeking increased with the loss of the alternative non-drug reinforcer (ie, resurgence occurred) despite continued extinction conditions. The increase in cocaine seeking did not occur in another group of rats injected with SCH 23390 before the loss of the alternative reinforcer. These results suggest that removal of an alternative source of reinforcement may induce relapse of cocaine seeking and that the dopamine D1 receptor may have a role in this effect