Roy E. Ritzmann
DeGrace Hall, Room 220
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 movments with high-speed video systems that records 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 picture of a Blaberus discoidalis cockroach climbing over a wax barrier.
This picture represents a single frame of video taken at 500 frames per second as the cockroach climbs a plastic 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 (http://biorobots.cwru.edu).
· BIOL 216 – Organisms and Ecosystems
· BIOL 374/474 – Neurobiology of Behavior
Senior Research Personnel
Alan J. Pollack
Dr. Angela Ridgel
Current Graduate Students
Former Graduate Students
Dr. Martha Tobias
Dr. Michelle Murrain
Dr. Janet Casagrand
Dr. Songhai Chai
Dr. Andrew Tryba
Dr. Scott Nye
Ms. Lynda Dieckman
Mr. Daniel Greenblatt
Dr. Paul Schaefer
Watson, J.T, Ritzmann, R.E., and Pollack, A.J. (2002) Control of Obstacle Climbing in the Cockroach, Blaberus discoidalis II. Motor Activities Associated with Joint Movement. J.Comp. Physiol. A. 188:55-69.
R.D., Nelson, G.M., Bachmann, R.J., and Ritzmann, R.E. (2001) Toward
Mission Capable Legged Robots through Biological Inspiration. Autonomous
Robots, 11 (3):215-220.
Ritzmann, R.E., R.D. Quinn, J.T. Watson, S.N. Zill (2000) Insect walking and biorobotics: A relationship with mutual benefits. Bioscience 50:23-33.
Quinn, R.D. and R.E. Ritzmann (1998) Construction of a Hexapod Robot with Cockroach Kinematics Benefits both Robotics and Biology. Connection Sci. 10:239-254.
Ritzmann, R.E. and R.C. Eaton (1997) Neural substrates for initiation of startle responses. In Neurons, Networks, And Motor Behavior eds. Paul S.G. Stein, Sten Grillner, Allen I. Selverston, and Douglas G. Stuart, MIT Press. Pp 33-44.
Pollack, A.J. , R.E. Ritzmann, J.T. Watson (1995) Dual pathways for tactile sensory information to thoracic interneurons in the cockroach. J. Neurobiol 26:33-46.
Ritzmann, R.E. (1993) The neural organization of cockroach escape and its role in context-dependent orientation. In Biological Neural Networks in Invertebrate Neuroethology and Robotics. R.D. Beer, R.E. Ritzmann and T. McKenna eds. Academic Press, pp. 113-137.
Nye, S.W and R.E. Ritzmann (1992) Motion analysis of leg joints associated with escape turns of the cockraoch, Periplaneta americana. J. Comp. Physiol. A 177:183-194.
Ritzmann, R.E., A.J. Pollack, S.E. Hudson, A. Hyvonen (1991) Convergence of multi-modal sensory signals at thoracic interneurons of the escape system of the cockroach, Periplaneta americana. Brain Res. 563:175-183.