Gustatory plasticity in C. elegans involves integration of negative cues and NaCl taste mediated by serotonin, dopamine, and glutamate

While na?ve Caenorhabditis elegans individuals are attracted to 0.1-200 mM NaCl, they become strongly repelled by these NaCl concentrations after prolonged exposure to 100 mM NaCl. We call this behavior gustatory plasticity. Here, we show that C. elegans displays avoidance of low NaCl concentrations only when pre-exposure to NaCl is combined with a negative stimulus, e.g., a repellent, or in the absence of food. By testing serotonin and/or dopamine signaling mutants and rescue by exogenously supplying these neurotransmitters, we found that serotonin and dopamine play a role during the plasticity response, while serotonin is also required during development. In addition, we also show that glutamate plays an important role in the response to NaCl, both in chemoattraction to NaCl and in gustatory plasticity. Thus, C. elegans can associate NaCl with negative stimuli using dopaminergic, serotonergic, and glutamatergic neurotransmission. Finally, we show that prolonged starvation enhances gustatory plasticity and can induce avoidance of NaCl in most gustatory plasticity mutants tested. Only mutation of the glutamate-gated Cl(-) channel gene avr-15 affected starvation-enhanced gustatory plasticity. These results suggest that starvation induces avoidance of NaCl largely independent of the normal gustatory plasticity mechanism.     

Mechanisms underlying heightened risk taking in adolescents as compared with adults

Self-report surveys and behavioral tasks indicate greater risk-taking behavior in adolescents as compared with adults. However, the underlying causes of these behavioral differences remain unclear. The present study examined the possibility that adolescents may be more susceptible to immediate positive and negative outcomes than adults. We compared the behavior of adolescents and adults on a modified version of the Balloon Analogue Risk Task (Lejuez et al., 2002). The task required that participants press a button to "inflate" a series of balloons on a computer screen. Balloons inflated until either the participant released the button ("saved" balloons) or the balloon "burst." Accumulated points increased as the duration of the buttonpress increased; however, simultaneously, the likelihood that the balloon would burst also increased. Adolescents inflated balloons to a larger size prior to saving them than adults did, suggesting relatively higher levels of risk taking, although the adolescents' behavior was not uniformly risk prone. Further, in comparison with adults, behavior in adolescents was more influenced by whether a balloon was saved or had burst on the preceding trial, suggesting that sensitivity to immediate consequences is one mechanism that underlies the observed difference in risk taking.     

Social sharing of emotional experiences in Asian American and European American women

The present study investigated the relationships among ethnicity and social sharing of traumatic experiences in a sample of 88 East Asian and 88 European American women. Participants were asked to write about a traumatic experience for twenty minutes and then to rate how upsetting the experience was, how often they thought about it, how often and to whom they had previously disclosed the experience, as well as the perceived appropriateness of sharing the experience with different target audiences, e.g., friends and family members. The results indicated that Asian Americans reported speaking to others less frequently about the traumatic event and sharing it with fewer individuals, and tended to be more likely to share the event with friends than with family members when compared to European Americans. Asian Americans also reported thinking about the upsetting event less frequently than European Americans even though both groups reported that the events were equally upsetting. The more upsetting events were, the more often they were shared in the European American group, but there was no relationship between how upsetting events were and the degree to which they were shared in the Asian American group.     

Studying Help-Seeking for Symptoms: The Challenges of Methods and Models

Although the detection and experience of symptoms often stimulates an appropriate decision as to whether to visit to a healthcare professional (HCP), there are many occasions when it does not. Sometimes, people seek help for minor, transient conditions which would have resolved without the attention of a HCP, whereas at other times help is not sought for signs of life-threatening disease. Help-seeking behaviour concerns not only the decision of whether to seek help or not, but also the timing of that decision. The timing of consultations with HCPs has implications for our health, quality of life, treatment options and for the cost of healthcare services. This article discusses research and theory on help-seeking behaviour, with attention to the challenges of methods and models used in this area of research. One particular model, the ‘General Model of Total Patient Delay’, is outlined and critiqued to demonstrate the complex processes involved and highlight areas in need of further research and development.     

Anfänge und Entwicklung der Leistungsmotivation: (II.) in der Zielsetzung des Kleinkindes

Ohne ZusammenfassungDiese Arbeit ist Herrn Prof. Dr. Wolfgang Metzger zum 65. Geburtstag gewidmet.