The answer, they say, appears to be an adaptive increase in the size of the cerebellum in some fossil vertebrates. Scientists have long thought that the cerebellum should be important in bird flight, but they lacked direct evidence. To do so, she worked with biomedical engineers at Stony Brook University in New York to compare the brain activity of modern pigeons before and after flight. The researchers also detected increased brain activity in the so-called optic flow pathways, a network of brain cells that connect the retina in the eye to the cerebellum. The researchers cautioned that these are early findings, and brain activity changes during powered flight could also occur during other behaviors, such as gliding.