Encoding, consolidation, and retrieval of contextual memory: differential involvement of dorsal CA3 and CA1 hippocampal subregions

Studies on human and animals shed light on the unique hippocampus contributions to relational memory. However, the particular role of each hippocampal subregion in memory processing is still not clear. Hippocampal computational models and theories have emphasized a unique function in memory for each hippocampal subregion, with the CA3 area acting as an autoassociative memory network and the CA1 area as a critical output structure. In order to understand the respective roles of the CA3- and CA1-hippocampal areas in the formation of contextual memory, we studied the effects of the reversible inactivation by lidocaine of the CA3 or CA1 areas of the dorsal hippocampus on acquisition, consolidation, and retrieval of a contextual fear conditioning. Whereas infusions of lidocaine never impaired elementary tone conditioning, their effects on contextual conditioning provided interesting clues about the role of these two hippocampal regions. They demonstrated first that the CA3 area is necessary for the rapid elaboration of a unified representation of the context. Secondly, they suggested that the CA1 area is rather involved in the consolidation process of contextual memory. Third, they showed that CA1 or CA3 inactivation during retention test has no effect on contextual fear retrieval when a recognition memory procedure is used. In conclusion, our findings point as evidence that CA1 and CA3 subregions of the dorsal hippocampus play important and different roles in the acquisition and consolidation of contextual fear memory, whereas they are not required for context recognition.     

Environmental toxicants and developmental disabilities: a challenge for psychologists

Developmental, learning, and behavioral disabilities are a significant public health problem. Environmental chemicals can interfere with brain development during critical periods, thereby impacting sensory, motor, and cognitive function. Because regulation in the United States is based on limited testing protocols and essentially requires proof of harm rather than proof of lack of harm, some undefined fraction of these disabilities may reflect adverse impacts of this "vast toxicological experiment" (H. L. Needleman, as quoted in B. Weiss & P. J. Landrigan, 2000, p. 373). Yet the hazards of environmental pollutants are inherently preventable. Psychologists can help prevent developmental disabilities by mobilizing and affecting public policy, educating and informing consumers, contributing to interdisciplinary research efforts, and taking action within their own homes and communities to reduce the toxic threat to children.     

The development of distance estimation in optic flow

In three experiments we tested the ability of children aged 8 to 12 years and adults to locate a target in an optic texture flow projected onto the ground. During the exposure phase, a static target (diode) was lit up at 6 m or 8 m on the ground in front of the subject. During the pointing phase, the subject was asked to indicate the perceived location of the target with a laser pointer as soon as the target was switched off. In the first experiment, during both phases the optic texture (environment) was either motionless or approaching the subject. Results showed that target locations were significantly more underestimated within the moving texture than within the still texture. In the second experiment, a detailed error analysis showed that the differences of performance between children and adults were not due to differences in eye height. Errors can be described by a linear fit with the retinal speed of the optic flow surrounding the targets. Distance judgments improved from the age of 8 years onwards. In the last experiment we found the same kind of results with a receding texture and without stimulation in central vision. Results are discussed in terms of subject's capacity to compensate for the effect of linear vection produced by the optic flow.     

Whom would you rather help: an acquaintance not responsible for her plight or a responsible sibling?

When 2 persons--an acquaintance who could not have avoided a problem and a close relative who is responsible for her own plight--ask for help, attribution theory and sociobiology conflict about who will receive help. Attribution theorists assume that the nonresponsible acquaintance will be supported, but sociobiologists argue that the responsible sibling will receive help. The authors tested the hypothesis that characteristics of the situation affect which theory better predicts help giving. The results confirmed that in situations that do not affect life and death, a nonresponsible acquaintance would receive more help than a responsible sibling. But in life-or-death situations, inasmuch as the reproductive fitness of the person in need is in danger, a responsible sibling would be supported more than a nonresponsible acquaintance.     

Grammatical Gender Systems: A Linguist's Assessment

The notion of grammatical gender is defined and criteria for assigning nouns to genders are discussed, in particular semantic and formal criteria. Data from child language acquisition show that both semantic and formal criteria can be the basis of children's overgeneralizations, although the question of to what extent more opaque semantic or formal gender assignment criteria are available to children remains to be ascertained.     

Gender Differences in Cheating Attitudes and Classroom Cheating Behavior: A Meta-Analysis

Although academic dishonesty is a major problemin American colleges and universities, relatively littleresearch has investigated gender differences incheating. Based on the differential socialization theory of gender differences in moral reasoning(e.g., Chodorow, 1989; Gilligan, 1982) we expected that,compared to women, men would report more favorableattitudes toward cheating and more cheating behavior. We conducted a meta-analysis that included 8studies of gender differences in attitudes towardcheating, 34 studies of gender differences in cheatingbehavior, and 6 studies that investigated both attitudes and behavior. Although the mean effect size forgender differences in attitudes was of moderatemagnitude, equivalent to a correlation of r = .21, themean effect size for behavior was small, equivalent to r = .08. Behavior effect sizes also varied asa function of field of study, method of data collection,and country in which the study was conducted. We discussthe implications of our results for future research on gender differences in academicdishonesty.     

Middlemarch Revisited: Changing Responses to George Eliot

The American Journal of Psychoanalysis -