http://precedings.nature.com/tags/choice Recently posted documents tagged with 'choice' Nature Publishing Group en Nature Precedings http://precedings.nature.com/images/header_logo.gif http://precedings.nature.com http://precedings.nature.com/documents/3738/version/1 Assessing the relative reward value of cocaine and how it changes with repeated use represents a long-standing goal in addiction research. Surprisingly, recent experimental research in rats – the most frequently used animal model in the field – suggests that the reward value of cocaine may in fact be relatively weak at least in the majority of individuals. Here, we provide strong additional evidence that confirms and extends the validity and generality of this research. Specifically, we demonstrate that no matter how heavy is past cocaine self-administration, most rats value cocaine poorly and readily decide to quit when offered the opportunity of making a different choice (i.e., drinking water sweetened with saccharin, an otherwise biologically inessential rewarding behavior). On average, rats estimate that cocaine is worth about 10 times less than the alternative reward. Only a small minority of rats prefer to continue taking cocaine when offered the choice. These findings reveal the existence of a genuine resilience to cocaine addiction in the majority of rats, a phenomenon that has long been suspected, though not firmly demonstrated, in humans. Only a minority would be prone to develop this disorder. We propose that choice should serve as a behavioral screening assay to identify vulnerable individuals, among the resilient majority, in future experimental research on the determinants of cocaine addiction. http://precedings.nature.com/documents/3738/version/1 Wed, 09 Sep 2009 19:01:10 UTC Choice reveals that rats are majoritarily resilient to cocaine addiction hdl:10101/npre.2009.3738.1 2009-09-09 Serge H. Ahmed Nature Precedings 2009-09-09T19:01:10Z Manuscript Neuroscience Pharmacology http://creativecommons.org/licenses/by/3.0/ http://dx.doi.org/10.1038/npre.2008.2171.1 Our past experience is one of the primary sources of information when faced with a choice. We ask ourselves: “what will happen if I do this?” Accurately predicting the consequences of our actions is usually modeled by operant (instrumental) learning experiments. These types of experiments are often contrasted with classical (Pavlovian) conditioning experiments in a dichotomy. And indeed, different brain circuits mediate the acquisition of skills and habits (via operant/instrumental learning) and the acquisition of facts (via classical/Pavlovian learning). However, realistic learning situations always comprise interactions of skill- and fact-learning components (composite learning). Fixed flying Drosophila melanogaster at the torque meter provide one of the very few systems where the relationship of operant and classical predictors in composite learning can be studied with sufficient rigor. The latest experiments show that the textbook operant/classical dichotomy is misleading and that instead composite learning consists of multiple interacting memory systems. These interactions between predictive stimuli (classical component) and goal-directed actions (operant component) make composite conditioning more effective than the operant and classical components alone (learning-by-doing, generation effect). Rutabaga (rut) mutants are impaired in learning about the (classical) stimuli, but show improved (operant) behavior learning. This is the first evidence that operant and classical conditioning differ not only at the circuit, but also at the molecular level. The interaction between operant and classical components is reciprocal and hierarchical, such that the classical suppresses the operant component. Experiments with transgenic flies demonstrate that this suppression of operant learning is mediated by the mushroom-bodies and serves to ensure that the classical memories can be generalized for access by other behaviors. Extended training can overcome this suppression and transforms goal-directed actions into habitual responses. This interaction leads to efficient learning, enables generalization and prevents premature habit-formation. http://dx.doi.org/10.1038/npre.2008.2171.1 Wed, 17 Sep 2008 12:49:48 UTC Mushroom-bodies regulate habit formation in Drosophila doi:10.1038/npre.2008.2171.1 2008-09-17 Björn Brembs Nature Precedings 2008-09-17T12:49:48Z Presentation Genetics & Genomics Neuroscience http://creativecommons.org/licenses/by/3.0/