Biomedical subjects

Kathryn M Welsh

Publications and source records attributed to Kathryn M Welsh.

4 recordsLinked to original sources

PubMed2007

Cognitive fatigue of executive processes: interaction between interference resolution tasks.

A resource depletion framework motivated a novel strategy for investigating whether the central executive is unitary or separable into relatively independent subprocesses. The idea that tasks with overlapping neural representations may involve similar executive components was also critical to our approach. Of particular interest were tasks requiring resolution of interference among competing representations. Within a single experimental session intensive training reduced the ability to resolve interference on a transfer task if the training task placed high demands on interference resolution. Negative transfer was absent when interference resolution was minimally required by the task, or when the training and transfer tasks did not rely on overlapping neural representations. These results suggest a nonunitary central executive composed of separable subcomponents, at least one of which mediates interference resolution. Our results are consistent with an executive control process specialized for the selection of task-relevant representations from competitors. The results also agree with the view that higher cognitive processes are resource limited and can be temporarily depleted.

Adolescent↗

PubMed2005

Salivary cortisol changes in humans after winning or losing a dominance contest depend on implicit power motivation.

In two studies, one with an all-male German sample and the other with a mixed-sex U.S. sample, subjects competed in pairs on reaction time-based cognitive tasks. Participants were not aware that contest outcome was experimentally varied. In both studies, implicit power motivation, defined as the non-conscious need to dominate or have impact on others, predicted changes in salivary cortisol from before to after the contest. Increased cortisol post-contest was associated with high levels of power motivation among losers but with low levels of power motivation among winners, suggesting that a dominance success is stressful for low-power individuals, whereas a social defeat is stressful for high-power individuals. These results emerged only in participants tested in the afternoon, possibly because of greater variability in cortisol in the morning due to the rapid decline after the morning peak. These studies add to the evidence that individual differences greatly influence whether a social stressor like losing a contest activates the HPA axis in humans.

Adaptation, Physiological↗

PubMed2005

Effects of implicit power motivation on men's and women's implicit learning and testosterone changes after social victory or defeat.

Two studies examined interactions of implicit power motivation and experimentally varied victory or defeat in a contest on implicit learning of a visuomotor sequence associated with the contest outcome and changes in testosterone and self-reported affect. In men and women, power motivation predicted enhanced learning (sequence-execution accuracy) after a victory and impaired learning after a defeat. In men, power motivation predicted testosterone increases among winners and decreases among losers, and testosterone decreases mediated the negative effect of power motivation on learning in losers. In women, power motivation predicted postcontest testosterone increases, particularly among losers. In both men and women, self-reported affective states were influenced only by contest outcome and were unrelated to participants' testosterone changes or implicit learning.

Adult↗

PubMed2004

Selection requirements during verb generation: differential recruitment in older and younger adults.

Age-related differences in cognitive performance are well documented. These differences are most pronounced during tasks with high demands on cognitive control, and it has been proposed that selective alteration of prefrontal activity is associated with cognitive changes in old age. Here, differences in the neural systems underlying selection requirements for older and younger adults were investigated using functional magnetic resonance imaging (fMRI). A verb generation task was used, and selection requirements were varied with regard to whether each noun could be associated with either few (scissors-cut) or many (ball-bounce, kick, throw...) competing alternatives. The two age groups showed statistically equivalent behavioral performance across the task conditions but marked differences in activation. Across both age groups, high selection demands activated several regions including bilateral frontal, left anterior frontal, left inferior temporal regions, and the dorsal anterior cingulate cortex (ACC). Between-group comparisons using region-of-interest analyses revealed less activation for senior adults in left inferior frontal gyrus (IFG), left inferior temporal gyrus, and the anterior cingulate and higher activation in right inferior frontal gyrus compared to young adults. These findings indicate age-related changes in multiple regions contributing to aspects of selection requirements during verb generation.

Adolescent↗