Databasing molecular neuroimaging studies

Positron emission tomography analysis in molecular neuroimaging can either be “voxel-based” or “region-based”. Voxel-based studies are usually reported with reference to the Talairach stereotaxic system and appear with tables listing “hot spot” foci, indicating the centers of areas with significant difference between two groups of scans. The voxel-based approach is widely used in the cognitive functional neuroimaging literature. Databasing such studies has been advanced with the BrainMap database (Research Imaging Center, San Antonio, TX). The newest version of this database contains data from over 800 studies with an interface allowing for preprogrammed access to the data. To gain a more flexible access to such studies, we have constructed the Brede database which presently records data from 185 studies. Apart from cognitive studies, the Brede database also contains data from molecular neuroimaging studies. The experiments in the Brede database are associated with items in an taxonomy. The taxonomy contains items for, e.g., cognitive functions and neuroreceptors. Some of the items are linked with corresponding MeSH terms, items from SenseLab and other biomedical databases. The items are organized in a directed acyclic graph with the most general concepts (e.g., “neuroreceptor”) at the roots of the graph, while more specialized concepts (e.g., the 5-HT2A receptor) are at the leafs. The representation of the hot spots centers in standardized coordinate space together with the taxonomy enables the statistical modeling of the distribution of the Talairach coordinates conditioned on, e.g., function and neuroreceptor type. So far, we have implemented a line of multivariate analysis methods as well as volume-based similarity metrics that work on these distributions.