Age-related changes in working and reference memory performance and locomotor activity in the Wistar rat

Wistar rats of three age groups were tested in an automated tunnel-maze system of variable geometry to investigate whether changes in spontaneous locomotor activity and in learning and memory develop differentially or in a correlated fashion as a function of age. Senescent (30 months) as well as mature-adult (17 months) rats showed an age-correlated decline of locomotor activity as compared to the mature-young (5 months) group. Both working-memory (measured as within-trial arm discrimination performance) and reference-memory (measured as avoidance of "blind alley" visits) were severely affected in the senescent group, whereas the middle-aged animals suffered only from a working-memory deficit. The findings provide evidence that locomotor deficits do not necessarily interfere in the assessment of age-related changes in cognitive performance. Furthermore the results support the hypothesis that working and reference memory have different underlying physiological correlates and that these neuronal systems are differentially affected by the aging process.     

Listeriosis of the central nervous system in children beyond the neonatal period

Observations on three children with neurolisteriosis (one case of meningitis, two cases of meningoencephalitis, each Serovar 4 b), show that even after the neonatal period, listeriosis must not be ignored in the process of diagnosis and therapy. It is the bacteriological examination of the cerebrospinal fluid, together with the blood culture, and not clinical symptoms and serology that guarantee a timely diagnosis and therapy (ampicillin and gentamicin).     

Visual Elaboration Scale as a measure of imagery

We studied the correlation of one measure of imagery ability, the Visual Elaboration Scale, with two others, absorption of image and effort required to form a mental image. Significant correlations were obtained between the Visual Elaboration Scale and the other scales, with the exception of Absorption for women.     

Sleep in the dove Zenaida asiatica

Electrographic and behavioral observations were made in five adult birds of the genus Zenaida asiatica. Five different vigilance states were quantitated: (1) Active waking (Aw) was characterized by constant behavioral activity; the nuchal electromyogram was tonically active with bursts associated to movements. The electroencephalographic pattern was low voltage and high frequency. (2) Quiet waking (Qw) was characterized by diminished behavioral activity and the EEG pattern was similar to that of Aw. (3) Drowsiness (D) was characterized by behavioral calm. Frequency of cerebral activity diminished progressively, but there were short periods of desynchronization corresponding to brief awakenings. (4) Slow wave sleep (SWS); during this period there was behavioral rest and EEG pattern of continuous slow waves and the nuchal EMG was tonically reduced. Spindles of sleep were not observed. (5) Paradoxical sleep (SP), behaviorally characterized by phasic manifestations consisting of noddings originated by rapid falling down of head and bursts of rapid eye movements. EEG activity was like that of waking state. EMG activity was maintained at the same level as during SWS but sometimes it decreased lightly. Total atonie was not observed. Sleep percentages were higher when recordings were done during the nocturnal period.     

A developmental-genetic analysis of aggressive behavior in mice (Mus musculus): III. Behavioral mediation by heightened reactivity or immobility?

This research was designed to investigate development and behavioral mediation in lines of ICR mice that have been selectively bred for aggressive behavior. General behavioral reactivity and behavioral immobility have been implicated as potential mediators by prior analyses of preattack interactions. To evaluate the separate roles of these dispositions, the emergence of attacks in genetically selected lines was tracked for 11 years by three levels of analysis: over successive generations, over development, and over dyadic interactions. Convergent outcomes were observed in all three levels with respect to two findings: (a) Robust line differences were obtained in attack behaviors, and (b) strong associations were found between line differences in attacks and line differences in behavioral immobility. Conversely, all three levels of analysis indicated a weak and inconsistent association between line differences in attacks and measures of social and nonsocial reactivity.     

Solving the rod-and-frame test in a tachistoscopic presentation: Effects of stimulus size and perceptual style

This research was undertaken to demonstrate, with correlational evidence, that presenting the rod-and-frame test (RIT) with either limited (tachistoscopic) or unlimited (Oltman’s, 1968, portable RFT) exposure time does not significantly affect the ranking of subjects. The underlying hypothesis is that the intersubject variability of performance on the portable RFT is due essentially to differences in sensitivity to the optostatic vection that appears automatically and almost immediately. Results of the tachistoscopic test show that the effect of angular size of the stimulus is similar to that described in the literature for unlimited time situations, and that subjects’ ranking is very similar regardless of the exposure time (W = .80). However, although a difference is observed between the means of low and high achievers in both types of RFT, intraindividual intertask homogeneity (correlation coefficient) is not verified in each of these subgroups. From these results, one can distinguish two processes in the RFT: the first, vections, has to do with the subject’s postural orientation and seems to playa great role in organizing interindividual differences. The second process, a more cognitive one, has a less striking effect and has to do with the selection of reference frames in perceptual organization.     

Mothers with hostile, Type A predisposing child-rearing practices.

The authors examined characteristics of Finnish mothers (N = 924) who use hostile child-rearing practices (i.e., they ignore the child, are punitive and irritable, and perceive the child as a burden), practices that have been shown (R?ikk?nen & Keltikangas-J?rvinen, 1992) to predispose children to Type A behavior. The results of this study indicate that two factors--Type A behavior in the mothers and the mothers' sociodemographic background (low occupational status, low educational level and young age)--increase the probability of the mothers' treating their children in a hostile manner. Also, the mothers of boys in this study reported more hostile child-rearing practices than the mothers of girls did.