A Closer Look at One Researcher's Work







Many scientists who are devoted to studying a particular disease or condition attribute their zeal to a life-changing moment. For physiologist Richard Nichols, that moment occurred during the Vietnam War, when he visited a VA hospital near Boston.

"In the spinal cord unit there," Nichols recalls, "was a patient who was paralyzed from the neck down from an injury he’d received during the first World War. He was treated well, but he’d been in bed for all these years.

"In the next bed was a young man in his early 20s who had also sustained a spinal injury. He had just come back from Vietnam, and had his boom box and everything. His doctor said, ‘The young guy is going to be just like the old guy in 30 years. We can make them comfortable, but that’s it.’

"I decided that was unacceptable," says Nichols.

As a basic scientist, Nichols studies the manner in which the spinal cord regulates posture and balance, and how injuries to the spinal cord or its peripheral nerves affect those functions. While the brain controls many motor functions, the spinal cord itself has some intrinsic motor capacities. Patterns of locomotion, for instance, are generated partly by spinal cord circuits that maintain a continuous feedback loop with the muscles. Such circuits also help keep the body upright by utilizing sensory information from the muscles.

The circuits can be disrupted by diseases like cerebral palsy, or injuries to the spinal cord or its peripheral nerves. However, in some cases of spinal cord injury, such as a broken neck, the circuits located at lower levels remain intact to a large extent. As the circuits can deteriorate through long disuse, the limbs of paralyzed individuals hoping to regain mobility must be exercised regularly to maintain the feedback loop. But these circuits also may hold the key to restoring balance and upright posture in addition to movement.

"When you think about it, it’s not sufficient to make your muscles go in a cyclic fashion," Nichols says. "You have to be able to stand up out of a chair and keep your balance as you go along. That is an enormous feat."

To learn more about how those circuits work, Nichols studies cats. That research has made him a primary target of animal rights activists, who say Nichols conducts torturous studies that have not produced any cures. But Nichols has accumulated substantial evidence that the spinal cord and the musculoskeletal system are responsible for maintaining posture — evidence that will provide the basis for designing rehabilitation strategies for patients with spinal cord injury.

What Nichols does is this: He operates on a cat, severing a nerve going to a single muscle, then immediately reattaches it in the same operation. As the cat heals, the muscle regains its full strength, but the sensory information the muscles send to the spinal cord is permanently disrupted, resulting in some loss of dexterity. The barely noticeable impairment can be measured using state-of-the-art methods when the cat performs certain exercises, such as walking up and down ramps and jumping onto platforms.

Sometimes, Nichols needs to make more specific, invasive physiological measurements. To do this, he deeply anesthetizes the cat, then exposes the muscles he needs to examine. At the end of the procedure, the animal is euthanized with an overdose of anesthesia. The cat feels nothing during the entire process.

"I don’t like killing animals," Nichols says. "I dislike it very much."

But he uses cats because a great deal of information about feline spinal cord and motor coordination functions already is available, having been compiled by scientists over the past century. Their contributions enable researchers today to make major findings using relatively few animals. In addition, cats will be the first to benefit from any breakthroughs derived from this research.

Using cats also allows Nichols to control confounding factors that might muddy his results; this would be impossible in a study of human subjects with varying types and degrees of spinal injury.

"We’re still at the stage where we must depend primarily on animal experimentation," Nichols says, emphasizing that the cats living in his colony are thriving and healthy, with only minor impairment.


Excerpted from the Winter 2002 issue of Momentum

Questions and answers with Physiology Professor T. Richard Nichols

Questions and answers about research with animals at Emory

Examples of biomedical research at Emory involving animals


© 2002 Emory University