α7 Nicotinic Receptor Subunits Are Not Necessary for Hippocampal-Dependent Learning or Sensorimotor Gating: A Behavioral Characterization of Acra7-Deficient Mice

The α7 nicotinic acetylcholine receptor (nAChR) subunit is abundantly expressed in the hippocampus and contributes to hippocampal cholinergic synaptic transmission suggesting that it may contribute to learning and memory. There is also evidence for an association between levels of α7 nAChR and in sensorimotor gating impairments. To examine the role of α7 nAChRs in learning and memory and sensorimotor gating, Acra7 homozygous mutant mice and their wild-type littermates were tested in a Pavlovian conditioned fear test, for spatial learning in the Morris water task, and in the prepulse inhibition paradigm. Exploratory activity, motor coordination, and startle habituation were also evaluated. Acra7 mutant mice displayed the same levels of contextual and auditory-cue condition fear as wild-type mice. Similarly, there were no differences in spatial learning performance between mutant and wild-type mice. Finally, Acra7 mutant and wild-type mice displayed similar levels of prepulse inhibition. Other behavioral responses in Acra7 mutant mice were also normal, except for an anxiety-related behavior in the open-field test. The results of this study show that the absence of α7 nAChRs has little impact on normal, base-line behavioral responses. Future studies will examine the contribution of α7 nAChR to the enhancement of learning and sensorimotor gating following nicotine treatments.     

Points of view analysis revisited: Fitting multidimensional structures to optimal distance components with cluster restrictions on the variables

Points of view analysis (PVA), proposed by Tucker and Messick in 1963, was one of the first methods to deal explicitly with individual differences in multidimensional scaling, but at some point was apparently superceded by the weighted Euclidean model, well-known as the Carroll and Chang INDSCAL model. This paper argues that the idea behind points of view analysis deserves new attention, especially as a technique to analyze group differences. A procedure is proposed that can be viewed as a streamlined, integrated version of the Tucker and Messick Process, which consisted of a number of separate steps. At the same time, our procedure can be regarded as a particularly constrained weighted Euclidean model. While fitting the model, two types of nonlinear data transformations are feasible, either for given dissimilarities, or for variables from which the dissimilarities are derived. Various applications are discussed, where the two types of transformation can be mixed in the same analysis; a quadratic assignment framework is used to evaluate the results.The research of the first author was supported by the Royal Netherlands Academy of Arts and Sciences (KNAW); the research of the second author by the Netherlands Organization for Scientific Research (NWO Grant 560-267-029). An earlier version of this paper was presented at the European Meeting of the Psychometric Society, Leuven, 1989. We wish to thank Willem J. Heiser for his stimulating comments to earlier versions of this paper, and we are grateful to the Editor and anonymous referees for their helpful suggestions.     

Right hemisphere participation in reading

This study examined whether the right hemisphere's contribution to lexical semantic processing is greatest when it is "disinhibited." Skilled reading may require the controlled modulation of interhemispheric interaction: the left hemisphere (or some other control mechanism) may regulate the subprocesses of reading by selectively "inhibiting" and "disinhibiting" right hemisphere function. Right-handed undergraduates concurrently performed two tasks: a lateralized semantic or rhyme task and a verbal memory task. It was hypothesized that right hemisphere reading processes would be disinhibited when the left hemisphere was "occupied" with the memory task. This hypothesis was supported for a subgroup of subjects who showed evidence of inhibition of right hemisphere function (i.e., left hemisphere dominance for lexical processing) when the lateralized semantic task was performed alone. Across subjects, there was a strong correlation between the degree of left hemisphere dominance in the single-task semantic conditions and the degree of disinhibition of right hemisphere function in the dual-task semantic condition.     

Two-month-old infants of depressed mothers show mild, delayed and persistent change in emotional state after non-contingent interaction

The aim of this study was to explore how early infants show different responses to non-contingent maternal behavior according to their past history of relations with their mother. Two groups of 2-month-olds interacted with their mother who was assessed as depressed (group 1) or non-depressed (group 2). Although they received a continuous image and voice of their mothers, the infants were presented either a 30-s contingent maternal communication (live episode 1) or a thirty second non-contingent episode (replay of prior maternal communication), or again a 30-s contingent live episode (live2). The lower percentage of negative facial expressions displayed during replay by infants of depressed mothers suggests on one hand that they are less sensitive to a non-contingent maternal behavior than infants of non-depressed mothers. However, within group comparisons demonstrate a notable difference: while infants of non-depressed mothers show a U curve of smile, infants of depressed mothers show decreasing smile throughout the three episodes. Taken together, these results plead in favour of an other profile of sensitivity displayed by infants of depressed mothers. Instead of the strong but short-term reaction of infants of non-depressed mothers, the response of infants of depressed mothers appeared to be a mild, delayed and more persistent change in emotional state. These findings are discussed in the light of possible cognitive and social incidence of passive avoidance of stressful events in infants of depressed mothers.     

Depressed mothers’ infants show less negative affect during non-contingent interactions

Infants of depressed and non-depressed mothers were videotaped interacting with their mothers in the [Nadel, J., Carchon, I., Kervella, C., Marcelli, D., & Reserbat-Plantey, D. (1999). Report: Expectancies for social contingency in 2-month-olds. Developmental Science, 2, 164–173] paradigm which consists of three segments including: (1) a free play, contingent interaction, (2) a non-contingent replay of the mothers’ behavior that had been videotaped during the first segment, and (3) a return to a free play, contingent interaction. As compared to infants of non-depressed mothers, infants of depressed mothers showed less negative change (less increase in frowning) in their behavior during the non-contingent replay segment. This finding was interpreted as the infants of depressed mothers being more accustomed to non-contingent behavior in their mothers, thus experiencing less violation of expectancy in this situation.     

Development of beliefs about the origins and controllability of dreams.

In three studies the authors investigated the development of beliefs about dreaming. Study 1 assessed 3- to 5-year-old children's beliefs about the origins and controllability of dreams. Results revealed significant changes in children's beliefs about the roles of behavioral experiences and mental processes in the generation of dream content. Results also revealed that young children consider both dreams and imagination to be highly controllable. In Study 2, preschool-age children, elementary school-age children, and adults received either imagination or dream stories and were questioned about controllability. In Study 3, emotional valence of the dream content was varied. Results of Studies 2 and 3 revealed significant development in beliefs that dreams are not subject to conscious control. Beliefs in controllability were higher among females. Study 3 showed that the emotional content of a dream affects these claims.