Oscillatory behavior is apparent in just about everything we can observe in the Universe. Planets revolve around the Sun and seasons occur in yearly cycles, moons orbit their planets and planets spin on their axis in monthly and daily cycles, plants and animals exhibit different types of behavioral activity in hourly cycles, and every minute you breath about 15 times and your heart beats about 70 times. In fact, each and every molecule is vibrating at some frequency depending on it's temperature. On the other end of the spectrum, electromagnetic waves of many types oscillate from many billions of cycles per second down to once per second or slower. Oscillatory behavior is so profound in biology that everything an organism does and how it is developed is dependent on some form of oscillatory mechanism. For example, the vertebrae in your spinal cord are formed by an oscillatory pattern of chemical factors across space that set up the distance between each bone. Long before human kind had any concept of electricity, neural systems used pulse coded modulation to transmit signal strength to other parts of the body. This is where my research interests begin. Our brain interprets signal strength from the rate that a particular neuron fires. Recent discoveries have shown that neural circuits also exhibit oscillatory activity that encodes more complex information about sensory stimulation from a collection of different inputs. The principle focus of work in my laboratory is to understand how the brain could use complex interactions of these oscillatory patterns to perform high levels of sensory processing. For example, a harbor seal can follow the trail of a fish for 100 meters or more only by using hydrodynamic cues and persistent vortices left behind by its swimming. The harbor seal uses oscillatory whisking of its whiskers to probe the environment, and could transpose the oscillatory information sent to its sensory cortex for high level processing to locate the fish, much in the same way that we can use the mathematical Fourier transform to extract information from oscillating systems in the frequency domain. Incorporation of standing wave theory also provides a mechanism by which long term memory in the brain could be explained.

The study of complex oscillatory patterns within intact neural tissue defies most existing techniques in neurobiology. Thus, the second major aim in my laboratory is to develop new neurophysiological procedures for imaging the electrical and chemical correlates of activity from large numbers of cells in the brain simultaneously. Since nerve cells swell during activation, and change their light scattering properties very quickly. We are developing high speed electronic systems to make movies of neural activity non-invasively using light and detecting changes in the back-scattered light from neural tissue. We are also developing high density electrode arrays to record the electrical potentials generated by the brain from 256 or more locations simultaneously. In collaboration with Dr. James Krueger, we are studying the plasticity of local neural group within the brain and their oscillatory activity during different behavioral states such as sleep. This work is generously supported by a grant from the NIMH, and the Sleep Research Society J. Christian Gillin Junior Faculty Award for 2002.