Roy E. Ritzmann
Professor of Biology
Professor of Neurosciences

DeGrace Hall, Room 220
rer3@po.cwru.edu
216-368-3554

Research Interests

Courses
Lab Personnel

Publications

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 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).

Courses

\xB7        BIOL 216 \x96 Organisms and Ecosystems

\xB7        BIOL 374/474 \x96 Neurobiology of Behavior

Lab Personnel

Senior Research Personnel

\xA0\xA0\xA0\xA0\xA0 Alan J. Pollack

\xA0\xA0\xA0\xA0\xA0 Dr. Angela Ridgel

Current Graduate Students

\xA0\xA0\xA0\xA0\xA0 Laiyong Mu

\xA0\xA0\xA0\xA0\xA0 Blythe Alexander

Former Graduate Students

\xA0\xA0\xA0\xA0\xA0 Dr. Martha Tobias

\xA0\xA0\xA0\xA0\xA0 Dr. Michelle Murrain

\xA0\xA0\xA0\xA0\xA0 Dr. Janet Casagrand

\xA0\xA0\xA0\xA0\xA0 Dr. Songhai Chai

\xA0\xA0\xA0\xA0\xA0 Dr. Andrew Tryba

\xA0\xA0\xA0\xA0\xA0 Dr. Scott Nye

\xA0\xA0\xA0\xA0\xA0 Ms. Lynda Dieckman

\xA0\xA0\xA0\xA0\xA0 Mr. Daniel Greenblatt

\xA0\xA0\xA0\xA0\xA0 Dr. Paul Schaefer

Selected Publications

Watson, J.T, Ritzmann, R.E., Zill, S.N. and Pollack, A.J. (2002) Control of Obstacle Climbing in the Cockroach, Blaberus discoidalis I. Kinematics. J.Comp. Physiol. A. 188:39-53.

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.

Schaefer, P.L. and R.E. Ritzmann (2001) Descending influences on escape behavior and motor pattern in the cockroach. J. Neurobiol. 49:9-28.

Quinn, 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.

Tryba, A.K. and R.E. Ritzmann (2000) Multi-joint coordination during walking and foothold searching in the Blaberus cockroach. I. Kinematics and electromyograms. J. Neurophysiol. 83:3323-3336.

Tryba, A.K. and R.E. Ritzmann (2000) Multi-joint coordination during walking and foothold searching in the Blaberus cockroach.II. Extensor motor pattern. J. Neurophysiol. 83:3337-3350.

Ritzmann, R.E., R.D. Quinn, J.T. Watson, S.N. Zill (2000) Insect walking and biorobotics: A relationship with mutual benefits.\xA0 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.

Watson, J.T. and R.E. Ritzmann (1998) Leg kinematics and muscle activity during treadmill running in the cockroach, Blaberus discoidalis:\xA0 I. Slow running. J. Comp. Physiol A. 182:11-22.

Watson, J.T. and R.E. Ritzmann (1998) Leg kinematics and muscle activity during treadmill running in the cockroach, Blaberus discoidalis:\xA0 II. Fast running. J. Comp. Physiol . A. 182:23-33.

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.