Interactive navigation through glial cells

Glial cells express a large variety of bio-electric and bio-chemical phenomena. A quantitative analysis shows that the brain consists of about 10 to 50 times more glial cells than neurons. Similar to neurons, glial cells implement voltage-dependent and ligand-gated membrane channels. Neurotransmitter receptors associated with ion-selective membrane channels have been described in several types of macroglial cells. Leech giant glial cells provide a good example for studying structural and physiological properties of this cell type. Confocal laser-scanning microscopy generates images from cutting (i.e. focus) planes of the object, in a way that, by varying the focus plane, the object can be resolved and scanned serially at several levels. Artifacts, such as transparent, low contrast, and blurred or fuzzy structures from neighboring slices must be filtered in order to reveal the capillary structure of the cell. With the microscope, the object cannot be rotated by ninety degrees, perpendicular to the viewing direction. Once scanned, the viewing direction cannot be altered any more. Computer graphics allows projections from any perspective angle, so that the cell can be studied in full detail. A visualization system should provide a flexible environment for interactively exploring the cell. Therefore, we have extended our InVIS (Interactive Visualization) system, which has been originally designed for medical applications (CT and MRI), to confocal microscopy. We describe the structure of our system and the addition of new features.