Hedonic and nucleus accumbens neural responses to a natural reward are regulated by aversive conditioning

The nucleus accumbens (NAc) plays a role in hedonic reactivity to taste stimuli. Learning can alter the hedonic valence of a given stimulus, and it remains unclear how the NAc encodes this shift. The present study examined whether the population response of NAc neurons to a taste stimulus is plastic using a conditioned taste aversion (CTA) paradigm. Electrophysiological and electromyographic (EMG) responses to intraoral infusions of a sucrose (0.3 M) solution were made in naïve rats (Day 1). Immediately following the session, half of the rats (n = 6; Paired) received an injection of lithium chloride (0.15 M; i.p.) to induce malaise and establish a CTA while the other half (n = 6; Unpaired) received a saline injection. Days later (Day 5), NAc recordings during infusions of sucrose were again made. Electrophysiological and EMG responses to sucrose did not differ between groups on Day 1. For both groups, the majority of sucrose responsive neurons exhibited a decrease in firing rate (77% and 71% for Paired and Unpaired, respectively). Following conditioning, in Paired rats, EMG responses were indicative of aversion. Moreover, the majority of responsive NAc neurons now exhibited an increase in firing rate (69%). Responses in Unpaired rats were unchanged by the experience. Thus, the NAc differentially encodes the hedonic value of the same stimulus based on learned associations.Our search for sustenance and pleasurable stimuli is often balanced by our desire to avoid punishment and harm. Similarly, neural systems responsible for generating approach behavior must be countered by signals that suppress approach behavior under contexts where approach is dangerous or maladaptive (Hoebel et al. 2007). The nucleus accumbens (NAc) is acutely involved in food intake and goal-directed, approach behavior. Pharmacological manipulations of the NAc promote food intake even in sated rats (Maldonado-Irizarry and Kelley 1995; Stratford and Kelley 1997). Lesions or inactivation of the NAc impair conditioned approach behavior (Cardinal et al. 2002; Blaiss and Janak 2009). Interestingly, drugs that lead to inhibition of select regions of the NAc increase positive hedonic responses to palatable taste solutions (Pecina and Berridge 2005). Recordings from individual NAc neurons have mirrored these findings. We and others have shown that consumption of palatable food stimuli is associated with decreases in the firing rate of the majority of responsive NAc neurons (Nicola et al. 2004b; Roitman et al. 2005; Taha and Fields 2005; Wheeler et al. 2008). In addition, decreases in NAc neural activity are associated with bouts of licking behavior for palatable stimuli (Taha and Fields 2006), and disruption of these decreases halt feeding bouts (Krause et al. 2010). Finally, decreases in NAc neural activity are associated with preferred locations previously paired with drug reward (German and Fields 2007). Thus, decreases in NAc activity appear to be closely linked to positive hedonic stimuli, stimuli that have been explicitly paired with them and behavioral approach.The NAc is also responsive to aversive stimuli (Carlezon and Thomas 2009; Levita et al. 2009). The delivery of aversive taste stimuli to rats is associated with increases in the firing rate of the majority of responsive NAc neurons (Roitman et al. 2005; Wheeler et al. 2008). In addition to responding to primary appetitive and aversive taste stimuli, NAc neurons develop responses to predictors of reward and aversion. Individual NAc neurons selectively encode cues that predict either appetitive (Roitman et al. 2005; Day et al. 2006) or aversive (Roitman et al. 2005) stimuli following purely Pavlovian conditioning or a combination of instrumental and Pavlovian conditioning (Setlow et al. 2003; Nicola et al. 2004a). NAc neurons come to encode departure from locations not associated with reward with the majority response being that of excitation (German and Fields 2007). Thus, NAc neurons appear to encode aversive stimuli and withdrawal behavior with increases in activity. These and other findings have led to the recent postulation that reward and aversion are differentially encoded by the activity of NAc neurons (Carlezon and Thomas 2009).Data supportive of the activity hypothesis (Carlezon and Thomas 2009) have been generated by the use of different stimuli to serve as appetitive or aversive primary or predictive stimuli. Thus, selective encoding could be biased by the sensory properties of each stimulus rather than their hedonic valence. When a novel, palatable taste is paired with visceral malaise, a Pavlovian association is made and a conditioned taste aversion (CTA) is established. Subsequent exposure to the once palatable stimulus is met with avoidance or aversion and rejection (Garcia et al. 1974; Schafe et al. 1995). Thus, the same taste stimulus can either be appetitive or aversive, depending on Pavlovian associations. Here, individual NAc neurons were recorded in rats (Paired) before (Day 1) and after a CTA (Day 5) was established and compared with rats that received equal exposure to the same stimuli but in an unpaired manner (Unpaired), and hence no CTA developed. Simultaneously, oro-motor behavior was characterized to provide an index of the associative strength of the taste stimulus. Using this paradigm, we determined that the population response of the NAc does indeed encode hedonic valence.     

Promoting Healing and Restoring Trust: Policy Recommendations for Improving Behavioral Health Care for American Indian/Alaska Native Adolescents

American Indian/Alaska Native youth represent the strength and continued survival of many Nations and Tribes. However, they currently experience numerous health disparities and challenges, including the highest rate of suicide among 15–24 year-olds in the United States. Our comprehensive review of the literature on the mental health of AI/AN youth highlighted seven focal causes of behavioral health disparities: (1) high levels of violence and trauma exposure and traumatic loss, (2) past and current oppression, racism, and discrimination, (3) underfunded systems of care, (4) disregard for effective indigenous practices in service provision, policy, and funding, (5) overreliance on evidence-based practices, (6) lack of cultural competence among systems of care and providers, and (7) barriers to care. Seven policy recommendations that recognize the importance of moving beyond exclusive reliance on western models of care and that seek to foster transformation of individuals, families, communities, behavioral health service systems of care, and social structures are presented, supported, and discussed.     

Addiction Topics in Counselor Educator Professional Development: A Content Analysis

Counselor educators prepare master's‐level counselors‐in‐training on addiction topics. This content analysis examined the frequency and types of addiction topics for counselor educator continuing education. The results revealed limited attention to addiction topics within professional literature and conference presentations.     

Sex,genes and hormones

The multidisciplinary symposium convened by the Society for Women's Health Research 'Sex Begins in the Womb' was held at the Crowne Plaza Cabana, Palo Alto, CA, USA, on 1 March 2002.     

Engaging contexts: Drawing the link between student and teacher experiences of the hidden curriculum

This article examines how academic disengagement (being off task, unenthusiastic and uncurious about learning) is facilitated by the hidden curriculum (the values, norms and beliefs transmitted via the structure of schooling), and mediated by race, ethnicity and gender for students in a working class elementary school. Additionally, we contextualize how a teacher was challenged by the hidden curriculum in her attempt to make her classroom environment engaging for all students. Participants included a young white female teacher and 21 second grade, low‐income students, of whom approximately 50% were white and 50% were Black or Latino/a. A teacher interview and fieldnotes covering 8 hours a week over 3 months comprised the data. Results indicated that students were required to show their engagement in particular ways that related to control and conformity. When they did not, they were reprimanded, which led to academic disengagement and the transmission of the hidden curriculum's message that school was not a place for them. This process was especially salient for Black and Latino boys, which indicated that the hidden curriculum was institutionalized. Results also showed that the hidden curriculum was a structural limitation for the teacher, as she was often thwarted in her attempts to create an academically engaging learning environment. Implications include strategies for school change and reform, including making the hidden curriculum more visible. Copyright © 2008 John Wiley & Sons, Ltd.     

Cognitive content-specificity in future expectancies: role of hopelessness and intolerance of uncertainty in depression and GAD symptoms

The present study examined cognitive content-specificity in future-event predictions associated with symptoms of depression and generalized anxiety disorder (GAD). College undergraduates (N=284) completed measures of depression, GAD, and rated their certainty that a given set of positive and negative outcomes were or were not likely to happen in their future. Participants also completed measures of hopelessness and intolerance of uncertainty (IU). Individuals (N=263) completed the same measures again 6 weeks later. Certainty in an absence of positive future outcomes was associated with symptoms of depression but not GAD, and hopelessness mediated this relationship - concurrently and when examining change scores over 6 weeks. Certainty in negative outcomes was concurrently associated with both symptoms of depression and GAD, and hopelessness partially mediated these relationships. IU predicted concurrent increases in depression and GAD symptoms, and negative-outcome certainty partially mediated the IU-depression but not the IU-GAD symptom relationship. Change in certainty did not mediate the relationship between changes in IU and GAD symptoms but partially mediated the relationship between change in IU and depression symptoms over time. Hopelessness appears to play a unique role in the relationship between reduced anticipation of positive future outcomes and depression. Although less clearly suggested by the data, IU may contribute to both depression and GAD symptoms but may do so through different pathways.     

Online communication, compulsive Internet use, and psychosocial well-being among adolescents: a longitudinal study

The present study investigated the relationships between adolescents' online communication and compulsive Internet use, depression, and loneliness. The study had a 2-wave longitudinal design with an interval of 6 months. The sample consisted of 663 students, 318 male and 345 female, ages 12 to 15 years. Questionnaires were administered in a classroom setting. The results showed that instant messenger use and chatting in chat rooms were positively related to compulsive Internet use 6 months later. Moreover, in agreement with the well-known HomeNet study (R. Kraut et al., 1998), instant messenger use was positively associated with depression 6 months later. Finally, loneliness was negatively related to instant messenger use 6 months later.     

On Enhancing the Cross‐Cultural Comparability of Likert‐Scale Personality and Value Measures: A Comparison of Common Procedures

This study aims to evaluate a number of procedures that have been proposed to enhance cross‐cultural comparability of personality and value data. A priori procedures (anchoring vignettes and direct measures of response styles (i.e. acquiescence, extremity, midpoint responding, and social desirability), a posteriori procedures focusing on data transformations prior to analysis (ipsatization and item parcelling), and two data modelling procedures (treating data as continuous vs as ordered categories) were compared using data collected from university students in 16 countries. We found that (i) anchoring vignettes showed lack of invariance, so they were not bias‐free; (ii) anchoring vignettes showed higher internal consistencies than raw scores where all other correction procedures, notably ipsatization, showed lower internal consistencies; (iii) in measurement invariance testing, no procedure yielded scalar invariance; anchoring vignettes and item parcelling slightly improved comparability, response style correction did not affect it, and ipsatization resulted in lower comparability; (iv) treating Likert‐scale data as categorical resulted in higher levels of comparability; (v) factor scores of scales extracted from different procedures showed similar correlational patterning; and (vi) response style correction was the only procedure that suggested improvement in external validity of country‐level conscientiousness. We conclude that, although no procedure resolves all comparability issues, anchoring vignettes, parcelling, and treating data as ordered categories seem promising to alleviate incomparability. We advise caution in uncritically applying any of these procedures. Copyright © 2017 European Association of Personality Psychology