Biomedical subjects

R H Grabner

Publications and source records attributed to R H Grabner.

4 recordsLinked to original sources

PubMed2005

EEG alpha band dissociation with increasing task demands.

In assuming functional differences between different EEG alpha frequency bands, recent studies emphasize the importance of using narrow (8-10 Hz or 10-12 Hz) instead of broad alpha frequency ranges (8-12 Hz). Due to individual differences in alpha activity, it has also been suggested to adjust alpha frequency bands individually for each participant. The present paper highlights the dissociating role of different task demands on the extent of event-related desynchronization (ERD) in different alpha frequency bands. In analyzing the data of four large-scale EEG studies (with sample sizes of 51, 58, 55, and 66, respectively) employing a wide range of cognitive tasks, we found evidence that the correlations between lower and upper alpha band ERD systematically decline as task demands increase.

Adult↗

PubMed2004

Extraversion and cortical activation during memory performance.

In this study we analyzed the influence of the personality dimension extraversion-introversion (E) on the level and topographical distribution of cortical activation. In 62 participants (32 introverts and 30 extraverts), we measured the extent of Event-Related Desynchronization (ERD) in the EEG during performance of a short-term memory (i.e., temporary maintenance of information) and a more complex working memory task (i.e., temporary maintenance and active manipulation of information). The results indicate that during performance of both tasks, introverts display a larger amount of ERD than extraverted individuals. Moreover, the present E effects largely match previous studies as to the restriction of these effects to lower EEG frequency ranges (approx. 4-8 Hz). Topographical analyses show that the E effects are primarily present over (right-hemispheric) frontal and parietal regions of the cerebral cortex.

Adult↗

PubMed2004

Intelligence and working memory systems: evidence of neural efficiency in alpha band ERD.

Starting from the well-established finding that brighter individuals display a more efficient brain function when performing cognitive tasks (i.e., neural efficiency), we investigated the relationship between intelligence and cortical activation in the context of working memory (WM) tasks. Fifty-five male (n=28) and female (n=27) participants worked on (1) a classical forward digit span task demanding only short-term memory (STM), (2) an attention-switching task drawing on the central executive (CE) of WM and (3) a WM task involving both STM storage and CE processes. During performance of these three types of tasks, cortical activation was quantified by the extent of Event-Related Desynchronization (ERD) in the alpha band of the human EEG. Correlational analyses revealed associations between the amount of ERD in the upper alpha band and intelligence in several brain regions. In all tasks, the males were more likely to display the negative intelligence-cortical activation relationship. Furthermore, stronger associations between ERD and intelligence were found for fluid rather than crystallized intelligence. Analyses also point to topographical differences in neural efficiency depending on sex, task type and the associated cognitive subsystems engaged during task performance.

Adolescent↗

PubMed2003

Sensitivity of human EEG alpha band desynchronization to different working memory components and increasing levels of memory load.

Event-related alpha band desynchronization is frequently used to analyze spatiotemporal cortical activation patterns during the performance of cognitive tasks. In the present paper the sensitivity of alpha band desynchronization to increasing levels of cognitive load and to different cognitive working memory components is investigated. A 27-channel electroencephalogram of 62 participants while solving (a) a short-term memory and (b) a working memory task (dual task), each with five levels of memory load, was analyzed. We found (a) a linearly increasing desynchronization in the upper alpha band with ascending cognitive load, and (b) evidence of the involvement of distinguishable cognitive components (storage and controlled attention) in the memory tasks.

Alpha Rhythm↗