Ghiselli and Brown conducted an experiment where they destroyed various subcortical regions of the brain in rats and tested their abilities to learn mazes compared to rats with no damage done to their brains. The rats with damaged brains didn't learn as well as the control rats, but no particular region seemed to be necessary to learn the mazes. There has also been experimental work done on higher apes and also studies done on humans who have suffered brain damage in various ways. The data gathered from these tend to confirm Lashley's theories.