A graphical anatomical database of neural connectivity

We describe a graphical anatomical database program, called XANAT (so named because it was developed under the X window system in UNIX), that allows t he results of numerous studies on neuroanatomical connections to be stored, compared and analysed in a standardized format. Data are entered into the database by drawing injection and label sites from a particular tracer stud y directly onto canonical representations of the neuroanatomical structures of interest, along with providing descriptive text information. Searches m ay then be performed on the data by querying the database graphically, for example by specifying a region of interest within the brain for which conne ctivity information is desired, or via text information, such as keywords d escribing a particular brain region, or an author name or reference. Analys es may also be performed by accumulating data across multiple studies and d isplaying a colour-coded map that graphically represents the total evidence for connectivity between regions. Thus, data may be studied and compared f ree of areal boundaries (which often vary from one laboratory to the next), and instead with respect to standard landmarks, such as the position relat ive to well-known neuroanatomical substrates or stereotaxic coordinates. If desired, areal boundaries may also be defined by the user to facilitate th e interpretation of results. We demonstrate the application of the database to the analysis of pulvinar-cortical connections in the macaque monkey, fo r which the results of over 120 neuroanatomical experiments were entered in to the database. We show how these techniques can be used to elucidate conn ectivity trends and patterns that may otherwise go unnoticed.