Tag: Fall 2013

Biomedical Engineering Seminar: Slow Potentials of the Sensorimotor Cortex During Rhythmic Movements of the Ankle

Biomedical Engineering Seminar:
Name: Ryan J. McKindles, doctoral candidate in Biomedical Engineering from Marquette University; Date: Friday, October 25 at 3:00 in U113 M&M
Title: “Slow Potentials of the Sensorimotor Cortex During Rhythmic Movements of the Ankle”

The objective of this research was to more fully understand the role of the human brain in the production of lower ex-tremity rhythmic movements. Throughout the last century, evidence from animal models has demonstrated that spinal reflexes and networks alone are sufficient to propagate ambulation. However, observations after neural trauma, such as a spinal cord injury, demonstrate that humans require supraspinal drive to facilitate locomotion. To investigate the unique nature of lower extremity rhythmic movements, electroencephalography was used to record neural signals from the sensorimotor cortex during three cyclic ankle movement experiments. First, we characterized the differences in slow movement-related cortical potentials during rhythmic and discrete movements. During the experiment, motion analysis and electromyography were used characterize lower leg kinematics and muscle activation patterns. Second, a custom robotic device was built to assist in passive and active ankle movements. These movement conditions were used to examine the sensory and motor cortical contributions to rhythmic ankle movement. Lastly, we explored the differences in sensory and motor contributions to bilateral, rhythmic ankle movements. Experimental results from all three studies suggest that the brain is continuously involved in rhythmic movements of the lower extremities. We ob-served temporal characteristics of the cortical slow potentials that were time-locked to the movement. The amplitude of these potentials, localized over the sensorimotor cortex, revealed a reduction in neural activity during rhythmic movements when compared to discrete movements. Moreover, unilateral ankle movements produced unique sensory potentials that tracked the position of the movement and motor potentials that were only present during active dorsi-flexion. In addition, the spatiotemporal patterns of slow potentials during bilateral ankle movements suggest similar cortical mechanisms for both unilateral and bilateral movement. Lastly, beta frequency modulations were correlated to the movement-related slow potentials within medial sensorimotor cortex, which may indicate they are of similar cortical origin. From these results, we concluded that the brain is continuously involved in the production of lower extremity rhythmic movements, and that the sensory and motor cortices provide unique contributions to both unilateral and bilat-eral movement.

Ryan McKindles is a 2006 Biomedical Engineering graduate from Michigan Tech.

Biomedical Engineering Seminar: Histotripsy for non-invasive liver cancer ablation

The Department of Biomedical Engineering presents Eli Vlaisavljevich, NSF Fellow in Biomedical Engineering, University of Michigan; Monday, October 21 – 4:00 pm in 129 Fisher;

Title: Histotripsy for non-invasive liver cancer ablation
and Students Perspective on Graduate School and Research

Abstract: Hepatocellular carcinoma (HCC) or liver cancer is one of the fastest growing cancers in the United States. Liver transplantation and surgical resection of liver tumors are proven treatment options but are associated with high rates of morbidity and mortality. Further, surgical resection or transplantation is not possible in many cases such as patients with decompensated cirrhosis. Current liver ablation methods are primarily thermal-based and share limitations due to the heat sink effect from blood flow through the highly vascular liver such as ineffective abla-tion near major vessels and unrealistic treatment times for larger tumors. We are developing histotripsy for the non-invasive treatment of liver cancer. Histotripsy is a non-thermal ultrasonic ablation method that fractionates tissue through the precise control of acoustic cavitation. Since histotripsy is non-thermal, it is not affected by the heat sink effect from blood vessels and does not share the limitations associated with thermal ablation methods. We are cur-rently working to develop histotripsy as a non-invasive liver cancer ablation technique capable of selectively ablating liver tumors while preserving the healthy tissue and major hepatic vessels surrounding the tumors.

Biography: Eli Vlaisavljevich graduated from Michigan Tech University in 2010 with a B.S. in Biomedical Engineering and is a currently pursuing his Ph.D in Biomedical Engineering at the University of Michigan. In addition to his research presentation, Eli will also give a brief overview of his experience in Ann Arbor and provide some information about graduate opportunities at the University of Michigan.

Biomedical Engineering Graduate Seminar: Optical Coherence Tomography

The Department of Biomedical Engineering presents Xuan Liu, PhD, Assistant Professor, Department of Biomedical Engineering, Michigan Technological University; Friday, October 11 – 3:00 pm in U113 M&M Building

Title: Smarter Optical Coherence Tomography for Biomedical Applications

Optical coherence tomography (OCT) is a three-dimensional, high speed, high resolution imaging modality with a broad range of biomedical applications. For example, OCT has become a standard diagnostic device in clinical ophthalmology. Besides diagnosis, OCT also has great potential in surgical guidance. A miniature OCT probe based on fiber-optic components can be integrated with a conventional surgical instrument for hand-held scanning. Such small, light-weight OCT probe can offer surgeon with freedom to access imaging sites of interest with large field of view in limited space and thus provide real-time intraoperative imaging and sensing capability to enhance surgical outcome. In the past few years, my research focus has been the development of a hand-held OCT system for intraoperative applications. In this presentation, I will show a few examples of our research efforts for the development of intraoperative hand-held OCT. With my extensive experience in using OCT to interrogate various properties (physical/chemical) of specimen and processing the obtained information with sophisticated algorithm at a high speed, I plan to develop smarter OCT systems for biomedical applications here at Michigan Tech.

Biography: Dr. Liu received her B.S. and M.S. degrees from Tsinghua University, Beijing, China. She started to study in the Johns Hopkins University since 2007 and received her Ph.D degree in 2011. Before joining the faculty of Michigan Tech, Dr. Liu worked as post-doctoral fellow in the Johns Hopkins University.

BME Graduate Seminar: Biomechanical Behaviour

BME Graduate Seminar; Dr. Ray Vanderby, Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine
Time: 3:00, Friday, September 27 in U113 M&M

Title: A Method to Quantify Biomechanical Behaviour in Soft TIssues

Computational and in vitro studies of softs tissues provide insight into functional behavior and demonstrate the intrinsic value of mechanical metrics. Methodological limitations, however, make in vivo data more challenging to gather and hence, rarely used clinically. Acoustoelastic (AE) analysis of ultrasound data has shown promise for providing in vivo mechanical data. AE studies analyze the changing ultrasound echoes in a loaded tissue and compute tissue stiffness from the AE equations. Using tendons as an example, this seminar will discuss how this concept can be implemented with standard ultrasound systems to characterize local tissue pathologies and mechanical compromise. Results provide localized tissue stress, strain, and stiffness from ultrasound echo intensities. We demonstrate our method on tendinopathy regions in human Achilles tendons and other examples under current investigation. Comparative local stiffnesses (normal versus tendinopathic) indicate the degree of mechanical compromise in the pathological region. Within limits of resolution and modeling assumptions, these data can quantify structural compromise and monitor functional healing in pathological tendons.