TORONTO - Scientists whose work ranges from pioneering ways to tackle childhood illness in developing countries to identifying how our biological clocks guide our everyday lives have been named as this year's recipients of the Gairdner Awards.

The awards, announced Wednesday, recognize some of the most significant medical discoveries from around the world. Among the world's most esteemed medical research prizes, the Gairdners distinguish Canada as a leader in science and provide a $100,000 prize to scientists whose work holds important potential.

"Our 2012 Canada Gairdner awardees are a group of modern-day explorers who have dedicated their lives to using basic science to discover answers to puzzling medical challenges," said Dr. John Dirks, president and scientific director of the Gairdner Foundation.

"Because of their tenacity and their dedication, we have a whole new realm of potential medical solutions open to us. It is our hope the awards continue to inspire researchers to conquer unchartered medical territory."

Three scientists received a Canada Gairdner International Award, which recognizes seminal discoveries or contributions to medical science, for discovering how the human biological clock ticks. They are: Jeffrey C. Hall, professor emeritus of biology at Brandeis University, Waltham, Mass.; Michael Rosbash, Howard Hughes Medical Institute, department of biology, Brandeis University; and Michael W. Young, Laboratory of Genetics, Rockefeller University in New York.

Circadian clocks are active throughout the body's cells, where they use a common genetic mechanism to control the rhythmic activities of various tissues and affect patterns of sleep, metabolism and response to disease. Understanding how the biological clock works has already allowed scientists to pinpoint irregularities in important sleep disorders.

Thomas M. Jessell of the Howard Hughes Medical Institute, Kavli Institute for Brain Science, Columbia University Medical Center in New York was awarded an International Gairdner for revealing the basic principles of nervous system communication.

Jessell identified the direct connection between the sensory neuron, which is responsible for allowing us to process what is happening in the world around us, and the motor neuron, which allows us to control how our muscles move to react to what we sense in that world.

The discovery is a step toward potentially creating strategies to treat neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA), as well as restoring movement in patients with spinal cord injuries.

Another International Gairdner goes to Dr. Jeffrey V. Ravetch, head of the Leonard Wagner Laboratory of Molecular Genetics and Immunology at Rockefeller University in New York for work demonstrating how the immune system can be both protective and harmful.

By identifying how antibodies work, and how auto-antibodies can be manipulated to prevent them from doing harm, Ravetch's work has laid the groundwork for the development of therapies for various autoimmune diseases such as lupus and arthritis, as well as cancer and infectious diseases.

The Canada Gairdner Global Health Award, recognizing a scientist for an advancement that has made or has the potential to make a significant impact on health in the developing world, goes to Dr. Brian M. Greenwood of the London School of Hygiene and Tropical Medicine.

Greenwood evaluated two groups of vaccines to prevent meningitis and pneumonia, and proved haemophilus and pneumococcal conjugate vaccines were highly effective in reducing mortality in African children. He also showed how deaths from malaria can be prevented using drugs and insecticide-treated bed nets.

The Canada Gairdner Wightman Award, given to a Canadian who has demonstrated outstanding leadership in medicine and medical science throughout his or her career, goes to Lorne A. Babiuk, vice-president (research) at the University of Alberta.

Babiuk's work has focused on studying how diseases are transmitted from animals to humans, while developing innovative vaccination approaches to control infectious diseases such as the rotavirus. Through his study of infectious disease and leadership in the field, Babiuk has helped reduce rates of death, illness and economic hardship caused by infectious diseases.

The Gairdner Awards will be presented Oct. 25 in Toronto.