The authors discuss the advantages and disadvantages of standard voxel-based analysis in functional imaging studies, particularly when examining specific brain regions. They propose a region of interest (ROI) analysis approach, which involves defining a region and performing statistical tests on the mean time course of voxels within that region. This method increases statistical power by avoiding multiple comparisons and can effectively recover signals if the ROI is correctly defined. The authors have developed a toolbox called "MarsBar" for ROI analysis within the SPM99 software package, which allows users to define and combine ROIs using various methods and extract time courses for further analysis. They highlight the potential benefits of ROI analysis in neuroimaging, especially as hypotheses about activation locations become more specific, and aim to simplify the implementation of such analyses.The authors discuss the advantages and disadvantages of standard voxel-based analysis in functional imaging studies, particularly when examining specific brain regions. They propose a region of interest (ROI) analysis approach, which involves defining a region and performing statistical tests on the mean time course of voxels within that region. This method increases statistical power by avoiding multiple comparisons and can effectively recover signals if the ROI is correctly defined. The authors have developed a toolbox called "MarsBar" for ROI analysis within the SPM99 software package, which allows users to define and combine ROIs using various methods and extract time courses for further analysis. They highlight the potential benefits of ROI analysis in neuroimaging, especially as hypotheses about activation locations become more specific, and aim to simplify the implementation of such analyses.