Accomplished neuroscientist becomes new Neuroscience Institute director

Aug. 17, 2004

AUSTIN, Texas—Dr. Daniel Johnston, a Baylor College of Medicine neuroscientist, has been named director of the Institute for Neuroscience at The University of Texas at Austin.

Johnston will also serve as a professor in the Section of Neurobiology in the College of Natural Sciences. His appointment was announced by College of Natural Sciences’ Dean Mary Ann Rankin.

“He is an outstanding scientist who has extensive experience overseeing a successful graduate program and serving as an education innovator,” Rankin said.

Johnston will replace Dr. Creed Abell, a medicinal chemistry professor in the College of Pharmacy, who has been institute director since 1992. High on Johnston’s agenda as director is the creation of the Center for Learning and Memory within the institute to expand his work of examining the basis of neural plasticity (changes in nerve cells with learning).

“My hope is to provide a major new research focus in the neurosciences on the UT campus,” Johnston said, “and bring world-class scientists to Austin to study aspects of learning, memory and cognition.”

A Baylor faculty member since 1977, Johnston began directing graduate studies for the Division of Neuroscience in 1988. He also has developed courses for graduate students and organized scientific meetings and has assisted junior colleagues while at Baylor and during three previous years on faculty at the University of Minnesota.

Johnston has investigated the mechanisms by which nerve cells in the brain change during learning and thought. Over the past 30 years, his research has led to new ways of studying these processes on a smaller scale than had previously been possible.

His most significant discoveries concern the region of nerve cells called dendrites, where signals from other nerve cells are received. Not only do dendrites process those thousands of simultaneous signals, but they also adapt to their role based on experience.

Johnston analyzes the changes in dendrites that lead to learning, and he visualizes these changes using light-sensitive fluorescent dyes, dendritic-patch-clamp electrophysiological recordings and extraordinarily fine imaging techniques. This work is complemented by computer modeling studies in which he reconstructs the biophysical properties of hippocampal neurons based on experimental data.

One aspect of dendritic function that has been the focus of Johnston’s research involves ion channels in the dendrites of living cells in the hippocampus, a part of the brain that is key to learning and memory. Ion channels are proteins in the cell membrane that act like tiny molecular gates, regulating the flow of various chemical ions (usually sodium, potassium and calcium) into and out of nerve cells in response to incoming signals, causing transient or long-term changes in the cells’ electrical properties.

Johnston is able to inject tiny hippocampal neurons with light-sensitive fluorescent dyes that bind ions. Using microscopes fitted with digital cameras and sensitive photodetectors, he and his colleagues can see and record minute changes in ion concentrations very precisely within a cell. He can follow the changes in ion concentrations via changes in light emission from the injected cells and obtain information about ion channel changes that are associated with incoming neural signals, learning and memory.

Some of this work was published last February in Nature Neuroscience, demonstrating that synaptic activity leading to changes in ion channel function in dendrites may be part of the mechanism of learning and memory storage. This outstanding work has implications for the study of normal brain function, as well as diseases affecting memory such as Alzheimer’s disease and the loss of cognitive function associated with normal aging. The findings have drawn attention from psychologists, pharmaceutical companies, and the general neuroscience community.

Johnston also studies epileptic seizures, with his most recent findings appearing in a July issue of the journal Science. The findings in an animal model suggest that dendrites of nerve cells in the temporal lobe of the brain may contribute to the initiation or continuation of seizures that occur in temporal lobe epilepsy, the most common form of epilepsy in adults. 

“Some of the same dendritic processes that play an important role in learning seem to go awry during the development of temporal lobe seizures” Johnston said. “Our research interests in learning and memory and seizure mechanisms are thus closely related.”

He earned a bachelor’s degree in electrical engineering at the University of Virginia in 1970 and a doctor’s degree in biomedical engineering and physiology in 1974 from Duke University. He went on to do postdoctoral training in epilepsy research at the University of Minnesota until 1977.

An author or co-author of 95 refereed science articles, Johnston also co-authored a seminal textbook called “Foundations of Cellular Neurophysiology.” He has served on the editorial boards of many journals, including the Journal of Neuroscience, the Journal of Neurophysiology, Epilepsy Research and Neuroscience.

His many honors include receiving a Michael E. DeBakey, M.D., Excellence in Research Award, a Corbin Robertson Presidential Award for Excellence in Education and two MERIT awards from the National Institute of Mental Health.

For more information contact: Barbra Rodriguez, College of Natural Sciences, 512-232-0675.