One kind of brain-scanning device is used by doctors to monitor normal as well as abnormal activity in a patient's brain. The device provides precise measurements of blood flow in the brain, a known indicator of how the brain is working. Unfortunately, the device requires patients to remain completely still with their heads in the scanning machine, which makes a very loud noise. Under these uncomfortable conditions, it is doubtful that doctors can get accurate measurements. A new head-mounted device that measures eye movements rather than blood flow and allows patients to move around will undoubtedly provide better brain measurements. Thus, the new head-mounted device should replace the older device at all hospitals and research institutions.