Individual differences in vocal activity rhythm: Fourier analysis of cyclicity in amount of talk

Speakers in informal conversations tend to alternate regularly between lower and higher amounts of talking; the periods of these low/high activity cycles are on the order of 3, 6, and 15 minutes. Statistically significant periodicities occurred in 55% of the conversations studied. The periodograms that describe the partition of variance among periodic components whow consistent individual differences in the cyclic patterning of vocal activity. Discriminant analysis used the amount of variance accounted for by each of the 12 lowest-frequency periodic components as discriminating variables to see whether speakers could be identified on the basis of the cyclic patterns in vocal activity. Speakers were discriminated and classified at levels well above chance. This suggests that there are consistent individual differences among speakers in the length of cycles in amount of talk.We gratefully acknowledge support from the Central University Research Fund and from the office of the Dean of Liberal Arts at the University of New Hampshire.     

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).