Sun, 20 Jul 2008 13:41:40 BST CiteULike: brembs generalization http://www.citeulike.org/user/brembs/tag/generalization CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/brembs/article/950204 <i>Learn Mem, Vol. 13, No. 5. (t 2006), pp. 618-628.</i><br /><br />In a permanently changing environment, it is by no means an easy task to distinguish potentially important events from negligible ones. Yet, to survive, every animal has to continuously face that challenge. How does the brain accomplish this feat? Building on previous work in Drosophila melanogaster visual learning, we have developed an experimental methodology in which combinations of visual stimuli (colors and patterns) can be arranged such that the same stimuli can either be directly predictive, indirectly predictive, or nonpredictive of punishment. Varying this relationship, we found that wild-type flies can establish different memory templates for the same contextual color cues. The colors can either leave no trace in the pattern memory template, leading to context-independent pattern memory (context generalization), or be learned as a higher-order cue indicating the nature of the pattern-heat contingency leading to context-dependent memory (occasion setting) or serve as a conditioned stimulus predicting the punishment directly (simple conditioning). In transgenic flies with compromised mushroom-body function, the sensitivity to these subtle variations is altered. Our methodology constitutes a new concept for designing learning experiments. Our findings suggest that the insect mushroom bodies stabilize visual memories against context changes and are not required for cognition-like higher-order learning. Context and occasion setting in Drosophila visual learning. B Brembs J Wiener doi:10.1101/lm.318606 Learn Mem, Vol. 13, No. 5. (t 2006), pp. 618-628. 2006-11-17T14:42:36-00:00 2006 Learn Mem 1072-0502 13 5 618 628 behavior classical condijtioning conditioning context drosophila generalization learning memory neurobiology neuroscience occasion operant pavlovian setting visual http://www.citeulike.org/user/brembs/article/950202 <i>Learn Mem, Vol. 13, No. 5. (t 2006), pp. 629-637.</i><br /><br />We have used a genetically tractable model system, the fruit fly Drosophila melanogaster to study the interdependence between sensory processing and associative processing on learning performance. We investigated the influence of variations in the physical and predictive properties of color stimuli in several different operant-conditioning procedures on the subsequent learning performance. These procedures included context and stimulus generalization as well as color, compound, and conditional discrimination (colors and patterns). A surprisingly complex dependence of the learning performance on the colors' physical and predictive properties emerged, which was clarified by taking into account the fly-subjective perception of the color stimuli. Based on estimates of the stimuli's color and brightness values, we propose that the different tasks are supported by different parameters of the color stimuli; generalization occurs only if the chromaticity is sufficiently similar, whereas discrimination learning relies on brightness differences. Different parameters support generalization and discrimination learning in Drosophila at the flight simulator. B Brembs N Hempel de Ibarra doi:10.1101/lm.319406 Learn Mem, Vol. 13, No. 5. (t 2006), pp. 629-637. 2006-11-17T14:41:38-00:00 2006 Learn Mem 1072-0502 13 5 629 637 behavior classical condijtioning conditioning discrimination drosophila generalization learning memory neurobiology neuroscience operant pavlovian