08. The Spinal Cord in Action
Joseph Fetcho
Joseph R. Fetcho, Neurobiology and Behavior, and research colleagues showed how the spinal cord controls speed of movement. Mapping neurons in the spinal cord of a larval zebrafish, the researchers found a pattern of activity that regulates the speed of the fish’s movement. They mapped how neurons in the tail end of the fish’s spinal cord become active during slow movements, while cells further up the spinal cord activate as movements speed up. With laser beams the researchers removed specific neurons in the lower spinal cord, making the zebrafish incapable of slow movements. When they removed nerves higher up the backbone, the fish had difficulty moving fast. Because larval zebrafish are transparent, the researchers could see their cells. They injected a fluorescent dye into the spinal cord, which lit up when calcium ions flooded in as the nerve cells activated with the fish’s movement. A confocal microscope with lasers allowed the researchers to image the cells at very high resolutions as the zebrafish moved at different speeds. The research provides insight into the structure and function of nerves in the spinal cord, which could help scientists assess whether nerves in an injured spinal cord are regrowing normally. Knowing the pattern of activity, the researchers can explore how it changes in diseased states. The research has implications for treating injured human spinal cords and Parkinson’s disease, where movements slow down and become erratic.