Novel Methods for the Visualization and Analysis of Functional Maps in Cortex

12 3 Flat Maps 3.1 Overview The cortical gray matter approximates a folded sheet in three-space. Hence, gray matter and the corresponding functional data can be represented in two-space by using a flattening algo- rithm. The developed tool uses such flattened representations of the cortical surface (flat maps) to segregate retinotopic visual areas. This chapter explains what flat maps are and how they are created. At first, some terms that are used later in the chapter are explained or defined. Then, background information is presented, e.g. a short introduction to magnetic resonance imaging (MRI) and functional MRI (fMRI). In the following sections flat maps and their advantages as well as their computation are described. This includes information on the recording of ana- tomical and functional data, the segmentation of gray matter, the flattening procedure, the alignment of different data sets, and the displaying of functional data in 2D. At the end, some types of flat maps are explained.