The brain is the most complex system we know of. It is the result of an evolutionary process and consists of billions of interconnected neurons. Connectivity between neurons is neither random nor regular. Most neurons produce sequences of pulses, by which signals between the neurons are exchanged. The signal exchange is delayed. Neurons perform nonlinear transformations on the incoming pulse trains. Noise enters at every step.

The signal flow in the brain is not just feedforward. Rather, feedback dominates most pathways. Dr. Wessel's group studies signal processing with neural feedback loops using the vertebrate isthmotectal loop as a model system. The isthmic nuclei receive a topographically organized projection from the tectum, to which they project back. The isthmotectal loop is present in most vertebrates, has been anatomically characterized in bird, frog, and turtle, and is experimentally accessible in these species both in vivo and in vitro. Dr. Wessel's group and his collaborators use electrophysiological, anatomical, and computational methods to study the mechanisms and functional roles of the isthmotectal loops in visual processing. The combined in vivo, in vitro, computational, and comparative investigation of isthmotectal feedback promises to uncover general principles of active signal processing with neural feedback loops.

• Gabbiani F, Metzner W, Wessel R, and Koch C (1996) From stimulus encoding to feature extraction in weakly electric fish. Nature 384:564-567.
• Luksch H, Khanbabaie R, and Wessel R (2004). Synaptic dynamics mediate sensitivity to motion independent of stimulus details. Nature Neuroscience 7:380-388.
• Brandt SF, Dellen BK, Wessel R (2006) Synchronization from disordered driving forces in arrays of coupled oscillators. Phys Rev Letters 96: 034104.

Dr. Wessel's Complete Publications List

Dr. Wessel obtained an MS in Physics from the Technical University Munich/Germany in 1989 and a Ph.D. in Physics from the University of Cambridge/England in 1992. During his postdoctoral training from 1993 to 1996 in neuroscience at UCSD in La Jolla, he was successively a Human Frontier Science Program Fellow and a German Research Council Fellow. In 1997, Dr. Wessel was appointed to Research Assistant Professor in the Department of Physics at UCSD. In 2000 he joined the faculty of Washington University in St. Louis as Assistant Professor of Physics and was promoted to Associate Professor in 2006. He also holds a joint appointment in the Department of Anatomy and Neurobiology at the Washington University School of Medicine.

In 2007, the Graduate Student Senate selected Dr. Wessel to receive Recognition for Excellence in Mentoring as part of the Outstanding Faculty Mentor Awards. These awards were created by graduate students in the Senate to honor faculty members whose commitment to graduate students and excellence in graduate training has made a significant contribution to the success of graduate students in Arts and Sciences at Washington University.