ROY E. RITZMANN, PHD
Professor of Biology
Professor of Neurosciences
Research Interests
Dr. Ritzmann's research is aimed at determining how animals move through the kinds of complex terrain found in natural settings. That is, if an animal wants to get from point A to point B but there are barriers and obstacles in between those points, how does it alter movements to climb over, tunnel under, or go around those objects? We have focused upon insect systems and in particular the cockroach, because they are very agile animals, yet they provide several technical advantages for the kinds of questions that we ask. We use a combination of techniques. First of all we record body and leg movements with high-speed video systems that record at 250 - 1000 frames per second. From these records we can establish the movements of each leg joint in three dimensions with remarkable precision. We can also correlate those movements with electrical activity recorded from nerves or muscles or from individual neurons. The neuromuscular arrangement of insects uses relatively few motor neurons for whole muscles. Indeed, in some cases a large muscle is innervated by only two distinctly different motor neurons. Where this occurs, electromyograms (EMGs) can provide detailed information about individually identified motor neurons.
Currently we are examining three questions. 1. What sensors do cockroaches use to evaluate barrier and how is that evaluation process being carried out. 2. How does the cockroach's brain process that sensory information and generate the necessary changes in movement to get around barriers? 3. How is the information in the higher neural centers used by motor control centers in the thoracic ganglia to alter leg movements and ultimately solve the problems posed by the barriers.
 A single frame of video taken at 500 frames per second as a cockroach climbs a plastic barrier.
 A Blaberus discoidalis cockroach climbing over a wax barrier.
While our studies are aimed at understanding locomotion in complex terrain, the data are also provided to members of Dr. Roger Quinn's Biorobotics laboratory. There it is used in efforts to design and build hexapod robots. Currently the Biorobotics group at CWRU is developing two lines of robotic devices. One is a large vehicle modeled closely after the joints of the cockroach that are essential for agile walking and climbing. The other is a much simpler device that uses biologically inspired principles derived from our insect studies, but implements them in abstract form on a simpler mechanical platform. We have also recently begun a project that uses motor activity recorded from a moving cockroach to control the movement of a robotic leg that was modeled after the front leg of the same species of cockroach. Movies of many of these and other robots can be viewed at the Biorobotics web site.
Movies
Cockroach movements (4.9 Mb)
Cockroach running on a treadmill (3.1 Mb)
Cockroach on an oil glass tether (12.6 Mb)
Cockroach climbing a block (2.7 Mb)
Intact cockroach on a smooth incline (1.6 Mb)
Brain-lesioned cockroach on an incline (2.2 Mb)
Cockroach with lesion in central complex of its brain walks normally through U-shaped track, making two correct left turns (2.9 Mb)
Same cockroach walks through track in opposite direction, should now turn to right but continues to turn left, now into the wall (9.2 Mb)
These movies in other file formats
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