SydneySCIENCE Highlights

Inner space to outer space: the fantastic voyage

As humanity’s knowledge of the world grows in detail, the inner workings of the brain may be the final frontier of scientific investigation. Our ability to perceive, interpret and react to the world is an enigma wrapped up in the millions of neurons in our brain. The delicate hunt is on for the secrets of how this system works and the ways we can use this knowledge to halt disease, delay dysfunction and get the most out of our mental muscles.

Dr Martin Wechselberger, from the School of Mathematics and Statistics, is developing mathematical tools to examine the underlying dynamics of physiological rhythms. “Physiological rhythms like the beating of the heart, the activity patterns of neurons and the release of hormones are central for life,” reveals Wechselberger. “We are working on new methods to identify key parameters which control these rhythmic processes and to explain complex oscillatory patterns observed in systems like the brain.”

Investigating the origin and dynamics of these rhythmic processes, once the sole interest of physicians and experimental physiologists, is coming under increasingly close examination by physicists and mathematicians like Wechselberger. “Disruption of the rhythmic process beyond normal bounds or emergence of abnormal rhythms is usually associated with disease, so it’s a very worthwhile area to study.”

In the brain, a loss of chaotic signals is seen in recordings taken from patients with epileptic seizures. Wechselberger’s research is examining chaotic dynamics in an effort to derive new methods that could identify systems that have the potential to create complex rhythms. “Interdisciplinary communication with bioscientists is critical to answering some of these questions,” he says.

Wechselberger is also interested in thermoregulation in the brain, and how temperature fluctuations in the body are controlled. “We know that hypothalamic neurons sense changes in body temperature and integrate this information with sensory information from thermoreceptors in the skin. But we don’t know a lot about the specific ion channels that are responsible for thermosensitivity or how fever is generated,” says Wechselberger.

Previously, neurophysiological studies suggested that the warm sensitivity of certain hypothalamic neurons is due to selective ionic channels. However, this may not be the case. Wechselberger has designed a mathematical model to generate experimentally testable predictions and identify the key ionic channels and their thermosensitive properties.

“Preliminary results show that a single, unique thermosensitive channel is not necessary to explain neuronal warm sensitivity. Rather, it is possible that most of the neurons involved contain the same basic set of ionic channels, and it is simply the variation in the proportions of expressed channels that determines whether a neuron will be warm sensitive, temperature insensitive or silent.”

These findings may be important in understanding the underlying interactions between different regulatory systems controlled by the hypothalamus.

To read the complete story and other articles about science at Sydney, order a free copy of the SydneySCIENCE book.