The Body Electricity

It is surprising to realize how much the human body needs electricity--albeit in very small amounts--to function. Two major organs, the heart and the brain, would be useless tissue if it weren't for minute electric charges regulating the heartbeat and even smaller signals jumping from cell to cell in the brain. When trauma or disease disrupts these signals there are only precious minutes to spare before permanent damage occurs. Professor Nitish Thakor uses his electrical and computer engineering background to decipher the body's electric code.

For more than ten years Thakor and his research group have investigated fibrillation, or chaotic heart rhythm, with the intent to improve fibrillation detection and defibrillation techniques. Specifically, they have built computer models that mimic fibrillation and defibrillation, allowing them to investigate new defibrillation strategies. A current project analyzes the chaotic fibrillation signals to predict when to deliver electrical shock. Results of this research may lead to the use of microprocessor technology to develop an implantable defibrillator. "This illustrates how basic research can lead to clinically useful solutions and new technologies," Thakor says.

More recently, Thakor extended the focus of his research to include neurosensory technologies. He himself experienced a head injury that required brief hospitalization, so he is quite cognizant of the limitations physicians face when trying to monitor brain function accurately, especially after trauma. With the help of neurologists and anesthesiologists in the School of Medicine, Thakor is developing a new type of brain monitor that uses computer and mathematical algorithms and an electroencephalograph (EEG) to decipher brain signals, known as "evoked potentials" from the injured brain.

While doing research on brain injury, Thakor's team discovered a phenomenon which they have named "bursting." When studying the brain waves, doctoral candidate Vaibhava Goel noted little bursts of EEG power. As the patients began to recover following injury, the bursts became more consistent until they formed a continuous EEG pattern. "This discovery and the study it has spawned are examples of collaborative research and demonstrate the outstanding capabilities of our graduate and undergraduate students," Thakor says.

A Figure of Speech

Speech. To Xiaoqin Wang, assistant professor of biomedical engineering, perception of speech is the most important human behavior. It's how we communicate our unique emotions and intelligence to other beings. Wang's research is simply stated, yet very difficult to understand: how does the brain process speech? He concentrates his efforts on how the brain's cortex handles auditory signals at the single neuron level. "It's difficult to study this in humans because we don't have non-invasive tools to probe single neurons in the human brain," Wang explains. "But," he adds, "we're not the only species with well-developed communications sound--the basis of speech."

A team of bright-eyed, long-tailed creatures called marmosets aids Wang in his work. One of the smallest primate species, the New World monkeys make their home in the tropical forests of Central and South America. "They live in social groups and rely heavily on their vocalizations to communicate with each other," Wang says. "We study their communication sounds as a parallel system to human speech." Marmosets use over 20 basic vocal patterns and their combinations to communicate, and Wang and his research group are the first to characterize quantitatively and identify their high-pitched trilling and staccato calls. In his laboratory, Wang synthesizes the marmosets' "conversations" and plays the computerized version to the animals to note any behavioral differences and to record brain responses. As with humans, each marmoset has its own speech "signature," and the brain must be able to decode the differences to identify the speaker. In addition, Wang studies the vocalizations of young and mature marmosets to determine brain "plasticity," or the window of time in life when speech is most readily acquired.

"In primates it isn't very clear what components of speech are learned and what are purely genetic," Wang says. His research will help scientists and clinicians better understand the pathology of abnormal speech and will also play an important role in the development of speech recognition machines.