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Discrimination Learning (discrimination + learning)

Distribution by Scientific Domains

Life Sciences	45%

Selected Abstracts

PEAK SHIFT DISCRIMINATION LEARNING AS A MECHANISM OF SIGNAL EVOLUTION

EVOLUTION, Issue 6 2005
Spencer K. Lynn
Abstract "Peak shift" is a behavioral response bias arising from discrimination learning in which animals display a directional, but limited, preference for or avoidance of unusual stimuli. Its hypothesized evolutionary relevance has been primarily in the realm of aposematic coloration and limited sexual dimorphism. Here, we develop a novel functional approach to peak shift, based on signal detection theory, which characterizes the response bias as arising from uncertainty about stimulus appearance, frequency, and quality. This approach allows the influence of peak shift to be generalized to the evolution of signals in a variety of domains and sensory modalities. The approach is illustrated with a bumblebee (Bombus impatiens) discrimination learning experiment. Bees exhibited peak shift while foraging in an artificial Batesian mimicry system. Changes in flower abundance, color distribution, and visitation reward induced bees to preferentially visit novel flower colors that reduced the risk of flower-type misidentification. Under conditions of signal uncertainty, peak shift results in visitation to rarer, but more easily distinguished, morphological variants of rewarding species in preference to their average morphology. Peak shift is a common and taxonomically widespread phenomenon. This example of the possible role of peak shift in signal evolution can be generalized to other systems in which a signal receiver learns to make choices in situations in which signal variation is linked to the sender's reproductive success. [source]

Temporal Discrimination Learning in Abstinent Chronic Alcoholics

ALCOHOLISM, Issue 6 2002
Regina McGlinchey-Berroth
Background: Converging evidence from varied experimental paradigms has demonstrated that the cerebellum is involved in the timing of learned behavior. Given the documented neurological changes secondary to chronic alcoholism, particularly cerebellar degeneration, the ability of recovered chronic alcoholics to learn a temporal discrimination was assessed by using delayed eyeblink classical conditioning. Methods: Twelve abstinent alcoholic participants and 12 matched control participants were randomly presented 2 clearly discriminable tone conditioned stimuli that were individually paired with 2 different interstimulus intervals. Results: The data revealed a significant alteration in the abstinent alcoholics' peak latency measure at the long interstimulus intervals and an overall impairment in their level of acquisition of conditioned responses. No group differences in extinction were observed. Conclusions: It was speculated that cerebellar cortical atrophy caused by years of alcohol abuse resulted in the peak latency alteration and that atrophy extending into deep cerebellar nuclei caused the overall impairment in conditioned response acquisition. [source]

The Effects of Feature-Label-Order and Their Implications for Symbolic Learning

COGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 6 2010
Michael Ramscar
Abstract Symbols enable people to organize and communicate about the world. However, the ways in which symbolic knowledge is learned and then represented in the mind are poorly understood. We present a formal analysis of symbolic learning,in particular, word learning,in terms of prediction and cue competition, and we consider two possible ways in which symbols might be learned: by learning to predict a label from the features of objects and events in the world, and by learning to predict features from a label. This analysis predicts significant differences in symbolic learning depending on the sequencing of objects and labels. We report a computational simulation and two human experiments that confirm these differences, revealing the existence of Feature-Label-Ordering effects in learning. Discrimination learning is facilitated when objects predict labels, but not when labels predict objects. Our results and analysis suggest that the semantic categories people use to understand and communicate about the world can only be learned if labels are predicted from objects. We discuss the implications of this for our understanding of the nature of language and symbolic thought, and in particular, for theories of reference. [source]

Neonatal alcohol exposure impairs acquisition of eyeblink conditioned responses during discrimination learning and reversal in weanling rats

DEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2007
Kevin L. Brown
Abstract Discrimination and reversal of the classically conditioned eyeblink response depends on cerebellar,brainstem interactions with the hippocampus. Neonatal "binge" exposure to alcohol at doses of 5 g/kg/day or more has been shown to impair single-cue eyeblink conditioning in both weanling and adult rats. The present study exposed neonatal rats to acute alcohol intubations across different developmental periods (postnatal day [PND] 4-9 or PND7-9) and tested them from PND26-31 on discriminative classical eyeblink conditioning and reversal. A high dose of alcohol (5 g/kg/day) dramatically impaired conditioning relative to controls when exposure occurred over PND4-9, but produced mild or no impairments when delivered over PND7-9. These findings support previous claims that developmental exposure period plays a critical role in determining the deleterious effects of alcohol on the developing brain. A lower dose of alcohol (4 g/kg/day) delivered from PND4-9,lower than has previously been shown to affect single-cue eyeblink conditioning,also produced deficits on the discrimination task, suggesting that discrimination learning and acquisition of responding to CS+ during reversal may be especially sensitive behavioral indicators of alcohol-induced brain damage in this rat model. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 243,257, 2007. [source]

Spatial conditional discrimination learning in developing rats

DEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2005
Kevin L. Brown
Abstract The present study established an effective procedure for studying spatial conditional discrimination learning in juvenile rats using a T-maze. Wire mesh located on the floor of the maze as well as a second, identical T-maze apparatus served as conditional cues which signaled whether a left or a right response would be rewarded. In Experiment 1, conditional discrimination was evident on Postnatal Day (PND) 30 when mesh,+,maze or maze-alone were the conditional cues, but not when mesh-alone was the cue. Experiment 2 confirmed that mesh-alone was sufficiently salient to support learning of a simple (nonconditional) discrimination. Its failure to serve as a conditional cue in Experiment 1 does not reflect its general ineffectiveness as a stimulus. Experiment 3 confirmed that the learning shown in Experiment 1 was indeed conditional in nature by comparing performance on conditional versus nonconditional versions of the task. Experiment 4 showed that PND19 and PND23 pups also were capable of performing the task when maze,+,mesh was the cue; however, the findings indicate that PND19 subjects do not use a conditional strategy to learn this task. The findings suggest postnatal ontogeny of conditional discrimination learning and underscore the importance of conditional cue salience, and of identifying task strategies, in developmental studies of conditional discrimination learning. © 2005 Wiley Periodicals, Inc. Dev Psychobiol 46: 97,110, 2005. [source]

Contextual modulation of spatial discrimination reversal in developing rats

DEVELOPMENTAL PSYCHOBIOLOGY, Issue 1 2005
Jerome H. Pagani
Abstract Reversal of discrimination learning is influenced by manipulation of the training context. In adult and developing rats, contextual changes made between acquisition and reversal aid the learning of the new discrimination, possibly by serving to release proactive interference from the originally acquired discrimination (M. E. Bouton & D. C. Brooks, 1993; N. Spear, G. Smith, R. Bryan, & W. Gordon, 1980). The present study sought to examine this effect in an appetitive T-maze task, as a function of different contextual manipulations. Rats of three ages, Postnatal Day (PND) 19, PND23, and PND30, were tested for their ability to acquire and reverse a position habit in a T-maze. Contextual changes were made between acquisition and reversal sessions and consisted of one of three manipulations: (a) texture; the texture of the maze floor was changed via the addition or subtraction of wire mesh; (b) maze; subjects were reversed in a different maze that was identical in construction to the training maze, but differed in spatial location; (c) texture and maze; subjects were shifted to the new maze, the floor of which differed in texture from the training maze but was otherwise identical in construction. Results showed that the texture,maze combination was an effective aid to reversal learning at all ages tested. The texture alone, however, was not effective at any age. The maze alone also was an effective cue for reversal, but proved to have the greatest effect for PND30 subjects. During ontogeny, the contextual modulation of reversal learning is importantly influenced by the nature and the salience of the contextual cue. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 46: 36,46, 2005. [source]

PEAK SHIFT DISCRIMINATION LEARNING AS A MECHANISM OF SIGNAL EVOLUTION

Cognitive and non-cognitive behaviors in an APPswe/PS1 bigenic model of Alzheimer's disease

GENES, BRAIN AND BEHAVIOR, Issue 2 2009
M. Filali
Neuropsychiatric signs are critical in primary caregiving of Alzheimer patients and yet have been relatively ignored in murine models. In the present study, APPswe/PS1 bigenic mice had higher levels of irritability than non-transgenic controls as measured in the touch escape test. Moreover, APPswe/PS1 mice showed poorer nest building than controls and a higher duration of immobility in the forced swimming assay. These results are concordant with the hypothesis of increased apathy and depression-like behavior in an Alzheimer's disease model. In addition, APPswe/PS1 bigenic mice were deficient in retention of passive avoidance learning and left,right discrimination learning, concordant with previous findings in other Alzheimer-like models. [source]

Cooperation and competition between the dorsal hippocampus and lateral amygdala in spatial discrimination learning

HIPPOCAMPUS, Issue 7 2006
Stephane Gaskin
Abstract The conditioned cue preference (CCP) was used to study how rats discriminate between adjacent arms on a radial maze. Chai and White (Behav Neurosci 2004, 118:770,784) showed that an intact dorsal hippocampus is required to learn this discrimination and that an amygdala-based conditioned approach response that produces an equal tendency to enter both arms is simultaneously acquired. In the present experiments, rats were preexposed to the maze with no food and trained by alternately confining them at the ends of two adjacent arms, one that contained food and one that did not. When given a choice between these arms with no food present, the rats spent more time on their food-paired arms, suggesting they had learned to discriminate their locations. Temporary inactivation of the dorsal hippocampus with muscimol during confinement on the food-paired arm had no effect on the discrimination, but inactivation while on the no-food arm impaired it. This pattern of effects was reversed in rats with amygdala lesions (inactivation on the food-paired arm impaired, but inactivation on the no-food arm had no effect on the discrimination), showing that hippocampus-based and amygdala-based learning interact to influence the behavior of normal rats in this situation. The dorsal hippocampus learns about locations that contain food and about locations that do not contain food. The amygdala-based tendency to enter the food-paired arm cooperates with hippocampus-based foraging for food on the food-paired, but the amygdala-based tendency to enter the no-food arm competes with hippocampus-based learning about the absence of food on that arm. © 2006 Wiley-Liss, Inc. [source]

The evolution of learning

BIOLOGICAL REVIEWS, Issue 2 2004
Bruce R. Moore
ABSTRACT Most processes or forms of learning have been treated almost as special creations, each as an independent process unrelated to others. This review offers an evolutionary cladogram linking nearly one hundred forms of learning and showing the paths through which they evolved. Many processes have multiple forms. There are at least five imprinting processes, eleven varieties of Pavlovian conditioning, ten of instrumental conditioning, and eight forms of mimicry and imitation. Song learning evolved independently in at least six groups of animals, and movement imitation in three (great apes, cetaceans and psittacine birds). The cladogram also involves at least eight new processes: abstract concept formation, percussive mimicry, cross-modal imitation, apo-conditioning, hybrid conditioning, proto-pantomime, prosodic mimicry, and image-mediated learning. At least eight of the processes evolved from more than one source. Multiple sources are of course consistent with modern evolutionary theory, as seen in some obligate symbionts, and gene-swapping organisms. Song learning is believed to have evolved from two processes: auditory imprinting and skill learning. Many single words evolved from three sources: vocal mimicry, discrimination learning, and abstract concept formation. [source]