Optimization of contrast detection power with probabilistic behavioral information

Optimal experimental designs for fMRI when the model matrix is uncertain

This study concerns optimal designs for functional magnetic resonance imaging (fMRI) experiments when the model matrix of the statistical model depends on both the selected stimulus sequence (fMRI design), and the subject's uncertain feedback (e.g. answer) to each mental stimulus (e.g. question) presented to her/him. While practically important, this design issue is challenging. This mainly is because that the information matrix cannot be fully determined at the design stage, making it difficult to evaluate the quality of the selected designs. To tackle this challenging issue, we propose an easy-to-use optimality criterion for evaluating the quality of designs, and an efficient approach for obtaining designs optimizing this criterion. Compared with a previously proposed method, our approach requires a much less computing time to achieve designs with high statistical efficiencies.

Optimal Design for Functional Magnetic Resonance Imaging Experiments

This paper provides an overview of optimal design for functional magnetic resonance imaging (fMRI) studies. We present the main types of fMRI designs, namely blocked and event-related designs, and common objectives of fMRI experiments, for example, localization of task-related activity in the human brain. Furthermore, we present an introduction into the methodology for analysis and optimization of fMRI experiments, for instance common analysis models and applied optimality criteria. We outline some of the problems encountered when optimizing fMRI experiments, for example, the temporal autocorrelation between measurements in fMRI data. The most important results for optimization of blocked and event-related designs with regard to the different design objectives are presented and explained. Finally, we conclude with future perspectives and challenges for optimization of fMRI experiments.

A within-subject ERP and fMRI investigation of orientation-specific recognition memory for pictures

Despite a large body of recognition memory research, its temporal, measured with ERPs, and spatial, measured with fMRI, substrates have never been investigated in the same subjects. In the present study, we obtained this information in parallel sessions, in which subjects studied and recognized images of visual objects and their orientation. The results showed that ERP-familiarity processes between 240 and 440 ms temporally preceded recollection processes and were structurally associated with prefrontal brain regions. Recollection processes were most prominent from 440 to 600 ms and correlated with activation in temporal, parietal, and occipital brain regions. Post-retrieval monitoring, which occurred in the ERP between 600 and 1000 ms as a long-lasting slow-wave over frontal channel groups, showed correlations with activation in the prefrontal and parietal cortex. These ERP/fMRI relationships showed some correspondences to source localizations of the investigated ERP memory effects.