Biomedical subjects

G E Larson

Publications and source records attributed to G E Larson.

10 recordsLinked to original sources

PubMed1996

Event-related potentials as indices of subclinical neurological differences in HIV patients during rapid decision making.

The authors examined decision making in HIV patients under slow and rapid information deliveries. Thirteen asymptomatic, HIV-infected (HIV+) subjects with known seroconversion dates and 13 healthy control subjects were instructed to detect the "oddball" target tones among nontarget tones during single-channel (slow) and dual-channel (rapid) deliveries. Event-related potentials (ERPs) from midline scalp sites, reaction time, and "hits" were recorded. Behaviorally, the two groups performed similarly, and during single-channel delivery they produced similar ERPs indexing target detection. However, during dual-channel delivery the HIV+ group showed atypical morphology in the region of the P300 cognitive decision-making component compared with the control group. Auditory ERPs elicited by rapid, dichotic stimulus presentations appeared sensitive to subclinical effects of HIV-related neuropathology in individuals who had been HIV-positive for 3 months to 8 years.

Acoustic Stimulation↗

PubMed1996

Mental rotation of static and dynamic figures.

Previous studies comparing performance on standard (i.e., static) and dynamic spatial test items have concluded that the two item types measure different abilities. Such conclusions about the uniqueness of static and dynamic spatial abilities seem premature, however, since only a limited number of dynamic spatial tasks have been utilized in research and these have differed markedly from their static counterparts. In the present studies, tasks were designed to require a common mental operation (mental rotation) under static and dynamic conditions. Correlations between static and dynamic performance ranged from .80 to .90. This appears to suggest that the emergence of a unique dynamic ability factor depends on the utilization of certain specialized tasks (e.g., arrival time tasks) with mental operations much different than those required by conventional spatial tests. In other words, it is apparently the requirement for different cognitive processes and not the processing of stimulus motion per se that distinguishes performance on some dynamic tasks from performance on some standard static tasks.

Adult↗

PubMed1994

Motivation: cause or confound in information processing/intelligence correlations?

The goal of the present study was to determine whether correlations between information processing scores and intelligence can be explained in terms of between-subject motivational differences. One hundred and nine male and female volunteer college students were tested on a battery of microcomputerized cognitive tests. One hundred of these subjects returned for a second session in which they were randomly assigned to an incentive or no-incentive condition and then retested. The effort expended on the tests was measured via heart rate, skin conductance, and a self-report questionnaire. Criterion measures, including the Advanced Otis-Lennon Test of Mental Abilities and Advanced Raven Progressive Matrices were also taken. The findings revealed that incentives had relatively modest effects on performance. In no case, however, did incentives affect the overall IQ-performance correlation for the tests used in the battery. These results support the view that correlations between information processing scores and intelligence reflect common mental capacities, rather than some affective variable such as motivation.

Adolescent↗

PubMed1994

Temporal synergism of corticosterone and prolactin in the Syrian hamster, Mesocricetus auratus.

To augment the limited work reported in the literature regarding testing of the hormonal temporal synergism hypothesis in Syrian hamsters (Joseph MM, Meier AH. Proc Soc Exp Biol Med. 1974;146:1150-5), a large experiment with female hamsters was conducted. Forty-eight received corticosterone at 18:00 h on January 21, 23, 25, 27, and 29 and ovine prolactin at one of six times of day beginning January 22 for 8 days; 36 received saline (at 18:00) and prolactin at one of the six times of day for 8 days; 35 received only prolactin at one of the six times of day for 8 days; and 16 received no injections. Twelve hamsters receiving corticosterone and prolactin and eight uninjected hamsters were on running wheels. The corticosterone and prolactin group not on wheels had a body weight gain and no circadian rhythm of weight gain, but did have circadian rhythms of response in organ weight, per 100 g of body weight, and in weights of fat pads and uteri. The corticosterone and prolactin group with access to running wheels gained in body weight and had larger ovaries and smaller fat pads. Hamsters receiving saline and prolactin had a body weight gain, but had no circadian rhythms of response in organ weights. The hamsters receiving only prolactin gained in body weight but had no rhythms of response, except for unexpected circadian rhythms in body weight gain and weights of fat pads. The uninjected hamsters had a modest weight gain. Most or all hamsters with access to running wheels free-ran, and the corticosterone injections did not appear to synchronize the locomotor activity rhythms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1990