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201.
Polysynaptic potentiation at different levels of rat olfactory pathways following learning 总被引:3,自引:0,他引:3 下载免费PDF全文
This study was aimed at investigating the consequences of learning on late polysynaptic components of evoked field potential signals recorded in parallel at different levels of the olfactory pathways. For this, evoked field potentials induced by electrical stimulation of the olfactory bulb were recorded simultaneously in the anterior piriform cortex, the posterior piriform cortex, the lateral entorhinal cortex, and the dentate gyrus. The different parameters of late components were measured in each site before and after completion of associative learning in anesthetized rats. In the learning task, rats were trained to associate electrical stimulation of one olfactory bulb electrode with the delivery of sucrose (positive reward) and stimulation of a second olfactory bulb electrode with the delivery of quinine (negative reward). In this way, stimulation of the same olfactory bulb electrodes used for inducing field potentials served as a discriminative cue in the learning paradigm. The data confirmed previous observation that learning was associated with a lowering in late-component-1 intensity of induction in the posterior piriform cortex. The use of simultaneous recording allowed us to further specify the consequences of learning on late-component distribution in the studied network. Indeed the data showed that whereas before learning, late component 1 was rather uniformly distributed among the recorded sites; following learning, its expression was facilitated preferentially in the posterior piriform cortex and lateral entorhinal cortex. Furthermore, learning was accompanied by the emergence of a new late component (late component 2), which occurred simultaneously in the four recording sites. The possible involvement of potentiation of polysynaptic components in recognition and/or consolidation processes will be discussed. 相似文献
202.
Pierre Priout Olivier Guédon Luc Proteau Gabriel M Gauthier 《Revue canadienne de psychologie expérimentale》2002,56(4):253-262
The goal of this study was to determine whether a sensorimotor or cognitive encoding is used to encode a target position and save it into iconic memory. The methodology consisted of disrupting a manual aiming movement to a memorized visual target by displacing the visual field containing the target. The nature of the encoding was inferred from the nature and the size of the errors relative to a control. The target was presented either centrally or in the right periphery. Participants moved their hand from the left to the right of fixation. Black and white vertical stripes covered the whole visual field. The visual field was either stationary throughout the trial or was displaced to the right or left at the extinction of the target or at the start of the hand movement. In the latter case, the displacement of the visual field obviously could only be taken into account by the participant during the gesture. In this condition, our hypothesis was that the aiming error would follow the direction of visual field displacement. Results showed three major effects: (1) Vision of the hand during the gesture improved the final accuracy; (2) visual field displacement produced an underestimation of the target distance only when the hand was not visible during the gesture and was always in the same direction displacement; and (3) the effect of the stationary structured visual field on aiming precision when the hand was not visible depended on the distance to the target. These results suggest that a stationary structured visual field is used to support the memory of the target position. The structured visual field is more critical when the hand is not visible and when the target appears in peripheral rather than central vision. This suggests that aiming depends on memory of the relative peripheral position of the target (allocentric reference). However, in the present task, cognitive encoding does not maintain the "position" of the target in memory without reference to the environment. The systematic effect of the visual field displacement on the manual aiming suggests that the role of environmental reference frames in memory for position is not well understood. Some studies, in particular those of Giesbrecht and Dixon (1999) and Glover and Dixon (2001), suggested differing roles of the environment in the retention of the target position and the control of aiming movements toward the target. The present observations contribute to understanding the mechanism involved in locating and grasping objects with the hand. 相似文献
203.
Viñas F Canals J Gras ME Ros C Domènech-Llaberia E 《The Spanish journal of psychology》2002,5(1):20-28
To assess the psychological and family factors associated with suicidal ideation in pre-adolescent children, we studied a sample of 361 students, average age 9 years old. Two groups were formed, on the basis of the presence (n = 34) or absence (n = 44) of suicidal ideation. Suicidal ideation was assessed with the Children's Depression Inventory and the Children's Depression Rating Scale-Revised. Depression, hopelessness, self-esteem, and perceived family environment were compared in both the suicidal ideation and the control groups. Students with suicidal ideation generally presented greater depressive symptoms and hopelessness, and lower self-esteem and family expressiveness, although there were differences both between sexes, and when the variable depression was controlled. Identifying these risk factors in pre-adolescents may have an impact on prevention of suicidal behavior at higher risk ages. 相似文献
204.
RAP: a new framework for visual categorization 总被引:1,自引:0,他引:1
Cognitive science might almost be defined as several disciplines communicating their different perspectives on the mind, the common object of study. However, domain-specific concepts and techniques can prevent, rather than foster, a communication of viewpoints. In this article, we develop a new framework for visual categorization in which the interaction between Represented (R) information and Available (A) information determine the Potent (P) information (symbolically, R ? A approximately P). We argue and illustrate that this framework helps to establish a common language to articulate issues common to low-, mid-, and high-level vision. More importantly, we present new techniques with which to visualize the so-far elusive constructs of representation and potent information. 相似文献
205.
Numerous previous investigators have explained species differences in spatial memory performance in terms of differences
in foraging ecology. In three experiments we attempted to extend these findings by examining the extent to which the spatial
memory performance of echidnas (or "spiny anteaters") can be understood in terms of the spatio-temporal distribution of their
prey (ants and termites). This is a species and a foraging situation that have not been examined in this way before. Echidnas
were better able to learn to avoid a previously rewarding location (to "win-shift") than to learn to return to a previously
rewarding location (to "win-stay"), at short retention intervals, but were unable to learn either of these strategies at retention
intervals of 90 min. The short retention interval results support the ecological hypothesis, but the long retention interval
results do not.
Electronic Publication 相似文献
206.
Prior studies provide consistent evidence of deficits for psychopaths in processing verbal emotional material but are inconsistent regarding nonverbal emotional material. To examine whether psychopaths exhibit general versus specific deficits in nonverbal emotional processing, 34 psychopaths and 33 nonpsychopaths identified with Hare's (R. D. Hare, 1991) Psychopathy Checklist--Revised were asked to complete a facial affect recognition test. Slides of prototypic facial expressions were presented. Three hypotheses regarding hemispheric lateralization anomalies in psychopaths were also tested (right-hemisphere dysfunction, reduced lateralization, and reversed lateralization). Psychopaths were less accurate than nonpsychopaths at classifying facial affect under conditions promoting reliance on right-hemisphere resources and displayed a specific deficit in classifying disgust. These findings demonstrate that psychopaths exhibit specific deficits in nonverbal emotional processing. 相似文献
207.
This work is divided in two papers (Part I and Part II). In Part I, we study a class of polymodal logics (herein called the class of "Rare-logics") for which the set of terms indexing the modal operators are hierarchized in two levels: the set of Boolean terms and the set of terms built upon the set of Boolean terms. By investigating different algebraic properties satisfied by the models of the Rare-logics, reductions for decidability are established by faithfully translating the Rare-logics into more standard modal logics. The main idea of the translation consists in eliminating the Boolean terms by taking advantage of the components construction and in using various properties of the classes of semilattices involved in the semantics. The novelty of our approach allows us to prove new decidability results (presented in Part II), in particular for information logics derived from rough set theory and we open new perspectives to define proof systems for such logics (presented also in Part II). 相似文献
208.
Data illustrating the biological week and chronomes are presented in recognition of extensive work of G. Hildebrandt. 相似文献
209.
Bernhard Plé 《Journal of Happiness Studies》2000,1(4):423-445
Auguste Comte (1798–1857) is the founder of a French school of thought that became famous for its encyclopaedic account of the sciences as well as for its exposition of what was designed as a way out of a state of intellectual and moral crisis. This essay demonstrates that there is a linkage between the diagnosis of crisis and the pursuit of happiness in Comte's foundation of positivism. It begins by distinguishing Comte's notion of positivism from that of a value-free science. In analysing Comte's peculiar usage of the term happiness, the essay shows that happiness is understood as the result of the convergence (consensus) of three components: a scientific conception of the world, the feelings of love and veneration, and a wisely ordered activity. The essay then demonstrates that the first of these components is of primary importance inasmuch as it is to frame a new horizon within which man is expected to return to a healthy state of mind, to reshape both his hopes and activities, and to discover his own participation in a supreme order acting through the laws of nature as well as through those of the civilization in which he lives. Conveying this new horizon to citizens of a lasting Republic is the sacred mission of sociology. The essay concludes by pointing out that Comte's conception of happiness can be assessed as unifying some main qualities of life as they are classified in Ruut Veenhoven's fourfold matrix. 相似文献
210.
The aim of this research is to model and simulate the loss of visual resolution as a function of retinal eccentricity in the perception of natural scenes. The model of visual resolution is based on a space-variant low-pass filter, having a variable convolution kernel according to retinal eccentricity. The parameters of the model are computed from psychophysical measures of visual acuity as a function of retinal eccentricity. The implementation of the model allowed us to generate images of scenes with nonhomogeneous space-variant resolution, simulating the filtering executed by the eye. These scenes are used to test and optimise the model by means of experiments in static vision (through tachistoscopic presentations) and in dynamic vision where the resolution of the scene is computed, in real-time, as a function of the location of gaze. 相似文献