Developmental dissociation between visual and auditory repetition priming: the role of input lexicons.

Contrasting theories posit the source of verbal repetition priming in the activation of preexisting memory representations in the input lexicons or, alternatively, in the formation of new episodic memory traces. The two hypotheses predict different outcomes from the comparison of developmental rates of visual and auditory verbal repetition priming. The activation theory predicts a developmental dissociation between the early maturation of auditory priming and the later maturation of visuo-verbal priming, contingent upon the discrepant acquisition rates of the auditory and visual input lexicons. The episodic theory, instead, does not make such an assumption. We administered visual and auditory implicit Stem Completion to 40 reading beginners (first-graders), 40 third-graders and 20 fifth-graders. Consistent with previous reports, auditory priming was stable across different age groups. Visual priming and a measure of lexicality in reading, instead, showed a parallel developmental increase passing from reading beginners to third-graders and to fifth-graders. In the overall group, visual priming and the measure of lexicality in reading were significantly associated. These data describe a new developmental dissociation in the memory abilities of normal children and provide further support for the hypothesis that repetition priming for words reflects facilitated access to previously established memory representations.

Plasticity and reorganization during language development in children with early brain injury.

Although some studies have reported subtle language deficits following early focal brain lesions (EFBL), most studies find no evidence for differential language outcomes as a function of lesion side or lesion type in children with congenital injuries to one side of the brain. However, recent prospective studies of the first stages of language development in English-speaking children with EFBL have reported greater delays in expressive vocabulary in children with left-hemisphere damage, particularly if the lesion involves left temporal cortex. In the present study, first stages in the development of word production were studied in 43 Italian children with congenital EFBL, between 13 and 46 months of age. As a group, the EFBL children were markedly delayed in expressive vocabulary. Among children who were in the first stage of language learning, delays were significantly greater with left-hemisphere injury. However, this left-right difference was not evident in children who had moved on to the next stage of language development, producing at least some sentences. Discussion centers on the role of developmental plasticity in determining the outcomes of early focal brain injury, suggesting that recovery from initial delays may take place in the early stages of language development, at least for some children.

[Statistic relation between seropositivity to Toxoplasma gondii and several risk factors in a sample of pregnant women]. / Relazione statistica tra sieropositività a Toxoplasma gondii ed alcuni fattori di rischio in un campione di donne gravide.

We analysed, in the period 1984-1986, the serum of 1733 pregnant women. The relation between the positivities and some probable factors of risk, alimentary habits and touch with tame animals has had valued by statistical method. The analysis shows no increase of risk in the group used to eat underdone meats compared with the group in touch tame animals.

[Comparison between 2 separation methods of IgM and IgG in serologic diagnosis]. / Confronto tra due metodi di separazione delle IgM dalle IgG nella diagnostica sierologica.

The concentrations of the IgG and IgM fractions have been determined on thirty whole sera and after treatment with protein A, or after chromatographic separation. The analysis of the differences has been effected with Student's t test. No statistically significant differences have been noted between the two methods of separation as far as IgM fraction is concerned, but, on the contrary, significant differences are present for the separation of IgG fraction.