Three-dimensional probabilistic maps of the occipital sulci of the human brain in standardized stereotaxic space

Developments in functional neuroimaging in normal human subjects, such as functional magnetic resonance imaging (fMRI), have permitted the mapping of several visual areas of the human brain and have already provided provisional identification of some of the visual areas that were first described in nonhuman primates. However, the lack of a detailed description of the sulcal patterns of the human occipital lobe makes it difficult to establish clear relationships between sulcal landmarks and identified visual areas with functional neuroimaging. In the present study we used magnetic resonance images to investigate the morphological variation of the human occipital sulci in both the left and right hemispheres of 40 normal adult human brains. We identified 11 occipital sulci, the parieto-occipital fissure and the temporo-occipital incisure, and their corresponding gray matter voxels were marked in the magnetic resonance volumes which had been transformed into the Montreal Neurological Institute standard proportional stereotaxic space. Probability maps were then constructed for each occipital sulcus. These probability maps provide a quantitative measure of the variability of the occipital sulci in standard stereotaxic space and are a useful tool to identify the location of voxels of other magnetic resonance imaging images transformed in the same stereotaxic space.