Thomas M. Jessell is an expert in how the brain controls movement. His work has helped shed light on many long-standing scientific questions, from how many types of neurons exist in the brain, to which circuits influence the emergence of fine motor skills. Dr. Jessell’s research also offers crucial insights into disorders of movement, such as ALS and Parkinson’s disease, in which the brain’s underlying circuitry is disrupted.Read more about Thomas M. Jessell, PhD >
January 30, 2018
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Thomas M. Jessell, PhD, a scientist who studies how the brain controls movement, is not above becoming a test subject himself. He once covered his body in electronic sensors that detected his muscle activity as he strolled across a room. The sensors showed different muscles contracting and relaxing at different times in an intricate pattern that kept him walking forward. When he then began to hop across the room like a kangaroo, the pattern changed. His muscles squeezed in unison to power each leap.
This demonstration, filmed for a lecture series at the Howard Hughes Medical Institute, illustrates how complicated even simple-looking movements can be. For decades Dr. Jessell has been investigating how our nervous system coordinates this complexity. How do our brains endow our fingers with the dexterity to play a guitar and our bodies with the agility to leap high into the air in a ballet?
His recent discoveries offer new insights into nerve cells in the spinal cord that work in concert to help us to move artfully and gracefully. Called interneurons, these cells provide quick, automatic feedback to our arms and legs, allowing a gymnast to adjust her limbs in a split second, with minimal involvement from the brain, as she flips on a balance beam.
In one study, Dr. Jessell and his colleagues found specific molecules in nerve cells that stimulate the hands and feet — but not in nerve cells that stimulate the arms and legs. These molecules could be evolution’s way of giving mammals the ability to perform intricate tasks; fine motor control is a fundamental skill that would have helped the earliest land animals to climb and grasp the branches of a tree, thereby escaping danger and surviving. It could also be a step toward explaining a concert violinist’s virtuosity with her instrument.
New details emerging from Dr. Jessell’s work could also have medical applications. In the early 2000s, his team found two molecules that can turn embryonic stem cells (immature cells that can transform into any type of cell in the body) into nerve cells called motor neurons that are dedicated to controlling movement. Could this be a first step toward treating diseases like amyotrophic lateral sclerosis (ALS), in which nerve cells waste away? Dr. Jessell, who is the Claire Tow Professor of Motor Neuron Disorders, hopes so; he sits on the board of Project ALS, a nonprofit that has raised over $75 million to fund research into the disease.
Dr. Jessell got his start in research as a student at Cambridge University. He had planned to study art; his mother, who restored pictures for a living, taught him to stretch canvases when he was young. But lectures on how drugs affected the brain inspired him to switch to science.
“I realized that being an artist or scientist is essentially the same thing,” says Dr. Jessell. “Both pursuits draw you out of yourself and into something larger; you have to be prepared to venture off in new directions.”
After investigating how morphine and opioid molecules regulate pain transmission at Cambridge, Dr. Jessell moved to Harvard University and applied his knowledge of molecules to experiments on nerve cells in the body. He was one of the first to do so, at a time when molecular biology, the study of the molecules that make living bodies work, was just beginning to take off. Then in 1985, he made another move, this time to New York, where he joined Drs. Eric Kandel and Richard Axel at Columbia University’s newly minted Center for Neurobiology and Behavior.
Drawing on his knowledge of molecular biology, Dr. Jessell first focused on identifying genes and chemicals broadly important for shaping the nervous system in the developing embryo. His early work supported the idea that certain molecules can guide a growing nerve over long distances to help it connect with the spine in the right spot. He found a gene that can turn embryonic cells into the types of nerve cells that control movement, called motor neurons. Questions followed: What makes a nerve in one part of the spine different from a nerve elsewhere in spine? How do nerves carrying information from the senses communicate with motor nerves to create reflexes? And how do motor nerves figure out which muscles to connect to as they develop?
“At the time, few had really studied the nervous system in any systematic manner,” says Dr. Jessell. “We were amongst the first to do so, and one of things we did was to define many of the genes that make motor neurons different from other neurons.”
Probing the workings of the nerve cells that control our movements, known collectively as the motor system, has been a long and painstaking voyage for Dr. Jessell and his colleagues. Like early explorers charting coastlines from wooden ships, neuroscientists have spent years identifying and piecing together small biological details to map the motor system. But the rewards for these years of meticulous studies have been profound. Understanding the motor system is the first step toward understanding how we and other animals interact with our environments, from a monkey peeling a banana to a barista pouring a coffee.
After more than 250 published research papers and decades mentoring young scientists, Dr. Jessell has now been instrumental in the creation of Columbia University’s new Zuckerman Institute. Along with Drs. Kandel and Axel, Dr. Jessell is bringing the Institute to life, inspired by the vision laid out by Columbia University president Lee Bollinger.
“We have been given the opportunity to explore Lee Bollinger’s vision for the new campus of Manhattanville, to create an institute in which young scientists who are experts in diverse areas can come together,” says Dr. Jessell, who is professor in the department of neuroscience and the department of biochemistry and molecular biophysics at Columbia University Medical Center’s College of Physicians & Surgeons. “It’s rare thing for scientists to have the freedom to explore their own curiosity, as they do at the Zuckerman Institute, and our general aspiration is to discover, within the next ten years, something about the brain that is of fundamental significance to humanity.”
Thomas M. Jessell, Howard Hughes Medical Institute Investigator, explores the human brain, the sophisticated product of 500 million years of vertebrate evolution, assembled during just nine months of embryonic development.