1. Traumatic brain injury (TBI) is the leading cause of death and disability in children causing, more than 50% of all childhood deaths. Each year, more than 150,000 pediatric brain injuries result in about 7,000 deaths and 29,000 children with new, permanent disabilities. Compared to adults with TBI, the long-term complications of TBI are often more devastating in children due to their age and developmental potential. Costs of pediatric TBI in the USA alone exceed $12 billion dollars annually. Leading causes of TBI include motor vehicle accidents, bicycle accidents, falls, and child abuse. In a 3-year project sponsored by the Thrasher Research Fund, we are developing a mathematical model of intracranial pressure (ICP) dynamics that extends current research models by incorporating physiologic data from actual pediatric TBI patients based on prospective data collected under controlled conditions by the Complex Systems Laboratory at OHSU. This project will develop a clinically useful model of ICP that can be used to help guide and predict the response to treatment in severe TBI. This represents a significant advance in the treatment of children with TBI and will serve as a basis for many additional research projects that incorporate clinical medicine, physiology, biomedical engineering and mathematics in a multi-disciplinary approach towards understanding and treating human disease. Figure 1. Example of microelectrode recording (MER) visualization of a patient with Parkinson's disease. A. Current visualization technique. The distinction between different brain structures is difficult to discern and only a few recording segments can be shown simultaneously. B. Anatomical map (Sagittal plane 12) corresponding to the assumed trajectory path with one of our visualization methods overlayed. C. Statistical properties of microelectrode recordings versus electrode depth. Our visualization clearly shows the boundaries of the target structure (STN) between 26 and 30 mm with the center at approximately 28 mm Microelectrode Recording Analysis for Stereotactic Neurosurgery for Stereotactic Neurosurgery As a consequence, most neurosurgeons use microelectrode recordings (MER) to locate the target with better precision. The neurosurgeon analyzes the MER signals by examining the time-domain behavior of the signal (Figure 1A) on an oscilloscope (or equivalent) while listening to the signal through conventional speakers. Although modern surgical workstations provide some tools for MER analysis, the techniques are cumbersome, difficult to interpret, require manual tuning, and require the neurosurgeon to mentally keep track of how the recordings change as the microelectrode moves through different brain structures. We are currently developing new analysis methods for extracellular microelectrode recordings (MER) that permit researchers to visualize how the patterns of neural activity vary spatially and between structures within brain tissue (Figure 1C). These methods will help neurosurgeons locate target structures within the brain during stereotactic neurosurgery for the treatment of Parkinson's disease and other movement disorders. These methods will enable neurosurgeons to locate target nuclei more accurately, faster, and with less training. Parkinson's disease (PD) is the second most prevalent neurodegenerative disease, affecting over 500,000 people in U.S.A. and about 4— 5 % of people over 85. Stereotactic neurosurgery is often used for patients whose condition has deteriorated and/or who are no longer responsive to drug therapy. One of the critical challenges to neurosurgeons who perform stereotactic neurosurgery in PD patients is locating the target structure within the brain. Current stereotactic methods for selecting the nominal target location use magnetic resonance imaging (MRI) with a stereotactic frame secured to the patient's head such that both the anatomic target and fiducial indicators on the frame can be visualized and registered in an image- processing workstation. However, insufficient image resolution (caused by small mechanical movements of the frame, image distortion, and shifting of the brain within the cranium) prevents precise localization of target structures. The mission of the BSP laboratory is to advance the art and science of extracting clinically significant information from physiologic signals. The objectives for this research program are to: Develop new methods of signal processing that extract useful information from physiologic signals. Advance our knowledge of pathophysiology through the investigation of behavior manifest in physiologic signals. Ground students with a solid foundation in statistics, signal processing, algorithm design, and algorithm assessment and provide them with the opportunity to experience the process of knowledge discovery, apply research methodology, disseminate knowledge, and learn the standards of peer review. Contribute to the regional needs of Portland and Oregon. We primarily focus on clinical projects in which the extracted information can help physicians make better critical decisions and improve patient outcome. We collaborate closely with Oregon Health \& Science University (OHSU), located less than 2 miles from Portland State University. The laboratory currently includes four PSU faculty members, six faculty at OHSU, and seven student members. James McNames, associate professor of Electrical and Computer Engineering, is the laboratory director. In 2004 alone we published 3 abstracts, 15 conference papers, 2 journal articles, and 2 book chapters. We have many research projects underway in areas ranging from traumatic brain injury to acupuncture. Here we give brief summaries of two of our current research projects. Therapy Optimization for Traumatic Brain Injury James McNames, PhD James McNames, PhD Associate Professor of Electrical and Computer Engineering Director of the Biomedical Signal Processing Laboratory (bsp.pdx.edu)