Biomedical subjects

Aureliu Lavric

Publications and source records attributed to Aureliu Lavric.

3 recordsLinked to original sources

PubMed2006

ERP differences with vs. without concurrent fMRI.

The acquisition of ERPs concurrently with fMRI in cognitive paradigms is appealing, but technically challenging. Little is known about the effects of the fMRI environment on the time-course and topography of previously documented ERP effects. We examined the replicability of ERP differences in the scanner at the level of individual subjects, using two cognitive paradigms and two statistical procedures. ERP P3 differences found outside the scanner in both paradigms were also robustly detected in the ERPs acquired during fMRI scanning. These P3 effects had equivalent time-courses and scalp topographies inside and outside the scanner. This replication at the level of individual data-sets has implications for the clinical applicability of ERP-fMRI and, more generally, for the quality of scanner recorded ERPs.

Adult↗

PubMed2006

Anxiety selectively disrupts visuospatial working memory.

On the basis of a review of the extant literature describing emotion-cognition interactions, the authors propose 4 methodological desiderata for studying how task-irrelevant affect modulates cognition and present data from an experiment satisfying them. Consistent with accounts of the hemispheric asymmetries characterizing withdrawal-related negative affect and visuospatial working memory (WM) in prefrontal and parietal cortices, threat-induced anxiety selectively disrupted accuracy of spatial but not verbal WM performance. Furthermore, individual differences in physiological measures of anxiety statistically mediated the degree of disruption. A second experiment revealed that individuals characterized by high levels of behavioral inhibition exhibited more intense anxiety and relatively worse spatial WM performance in the absence of threat, solidifying the authors' inference that anxiety causally mediates disruption. These observations suggest a revision of extant models of how anxiety sculpts cognition and underscore the utility of the desiderata.

Anxiety↗

PubMed2004

When 'go' and 'nogo' are equally frequent: ERP components and cortical tomography.

In human electrophysiology, a considerable corpus of studies using event-related potentials have investigated inhibitory processes by employing the 'go-nogo' paradigm, which requires responding to one type of event while withholding the response to another type of event. Two event-related potential waveform features (N2 and P3) have been associated with larger amplitude in nogo trials than in go trials. Traditionally, these differences were thought to reflect response inhibition. Recently, the source localization of N2 to the anterior cingulate cortex, as well as the colocalization of N2 with error-related negativity, has been interpreted in terms of conflict monitoring. In order to isolate the contribution of inhibitory processes, we matched the frequency of the go and nogo events, thus minimizing differences in response conflict between event types. A data-driven analytical procedure contrasted go with nogo events across the entire event-related potential segment and found that N2 reliably differentiated between the two conditions while P3 did not. Tomographical analyses of the N2 difference observed in conditions of equal go and nogo trial frequency localized N2 to the right ventral and dorsolateral prefrontal cortex. Because a growing body of evidence implicates these brain regions in inhibitory processes, we conclude that N2 does, at least in part, reflect inhibition.

Adolescent↗