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L Putnam

Publications and source records attributed to L Putnam.

8 recordsLinked to original sources
PubMed1992

A developmental event-related potential study of picture matching in children, adolescents, and young adults: a replication and extension.

Event-related potentials were recorded in a developmental study of picture matching using an adaptation of Posner's (1978) letter-matching tasks. Subjects ranging in age from 6-39 were asked to decide whether two line drawings, presented sequentially, were the same or different on the basis of physical (physical identity), nominal (name identity), or categorical (category identity) criteria. The amplitude of a negativity at 400 ms (Neg400) increased as the number of dimensions on which the two line drawings differed increased. This effect held for all age groups, and was interpreted as reflecting the degree of semantic and/or physical relationship between the two pictures. However, one finding for Neg400 did suggest a qualitative difference in processing mode between the younger and older subjects. Both Neg400 and P3b latencies showed highly significant linear age trends, decreasing with increasing age. These age-related changes were interpreted as demonstrating quantitative speed of processing differences among age groups. The latencies of both Neg400 and P3b increased as the matching criteria became more complex. Moreover, P3b latency increased as the number of dimensions on which the two pictures differed increased, and this did not interact with age. Although both Neg400 and P3b showed age-related changes in scalp distribution, the fact that each was related to the experimental variables in similar fashion in all age groups suggested that they were homologous components across the age range studied. Taken as a whole, the data support continuity of information processing during these tasks across a wide age range.

Adolescent↗
PubMed1990

Longitudinal and cross-sectional comparisons of young children's cognitive ERPs and behavior in a picture-matching task: preliminary findings.

Event-related brain potentials (ERPs) were recorded from 19 children (6-8 years old at initial testing) performing cognitive tasks in two longitudinal testing sessions administered one year apart. The task used was a modification, using pictorial stimuli, of Posner's (1978) letter-matching experiments. In separate blocks of trials, subjects had to decide whether two sequentially-presented slides were physically identical, shared the same name, or came from the same semantic category. Subjects indicated their choice via a same-different delayed response following the second slide. Behavioral data showed large effects of longitudinal Age reflecting increases in accuracy from Run 1 to Run 2. These effects were corroborated by analyses of cross-sectional Age, suggesting that the performance changes reflected cognitive growth, rather than practice effects. In a similar fashion, both N400 and P700 (classical 'P300') showed reductions in peak latency that appeared to be true age changes, since these latencies shortened as a function of Run of testing as well as cross-sectional Age, and there were no Run by Age interactions. Small sample sizes as well as methodological shortcomings of the current design limit the conclusions that can be drawn from these data. Nevertheless, this study demonstrates the feasibility and usefulness of a cross-sectional/short-term longitudinal design and provides information on the extent and direction of behavioral and ERP changes that can be observed over this limited age range.

Child↗
PubMed1990

Cardiac deceleration and E-wave brain potential components in young, middle-aged and elderly adults.

Event-related potentials (ERPs), heart rate, and behavioral data were recorded from young, middle-aged, and elderly adults during an S1-S2 recognition memory paradigm. Anticipatory and evoked cardiac decelerations decreased significantly with age, as did the accuracy of recognition memory. The E-wave prior to S2 did not differ with age, however, and was not correlated with heart rate deceleration in any age group. Correlations between physiological measures and performance were weak in all groups. Taken together, the data provide little support for the hypothesis that the poorer recognition memory of older adults is related to an increasing uncoupling of E-wave and anticipatory heart rate with age.

Adult↗
PubMed1989

Characterization and expression of a spliced leader RNA in the parasitic nematode Ascaris lumbricoides var. suum.

The parasitic nematode Ascaris spp. contains a 22-nucleotide spliced-leader (SL) sequence identical to the trans-SL previously described in Caenorhabditis elegans and other nematodes. The SL comprises the first 22 nucleotides of a approximately 110-base RNA and is transcribed by RNA polymerase II. The SL RNA contains a trimethylguanosine cap and a consensus Sm binding site. Furthermore, the Ascaris SL RNA has the potential to adopt a secondary structure which is nearly identical to potential secondary structures of similar SL RNAs in C. elegans and Brugia malayi.

Animals↗