some types of neurons may be found only in specific species. - Michael S. Gazzaniga

Hume concluded that many of the questions that philosophers asked were pseudo questions — that is, questions that cannot be answered with the likes of logic, mathematics, and pure reason because their answers will always be founded at some level on an unprovable belief, on an axiom. He thought that philosophers should stop wasting everyone’s time writing copiously about pseudo questions, dump their a priori assumptions, and rein in their speculations, as the scientists had. They had to reject everything that was not founded on fact or observation, and that included eliminating any appeal to the supernatural.

People with a right parietal lobe injury, for example, will commonly suffer from a syndrome called spatial hemi-neglect. Depending on the size and location of the lesion, patients with hemi-neglect may behave as if part or all of the left side of their world, which may include the left side of their body, does not exist! This could include not eating off the left side of their plate, not shaving or putting makeup on the left side of their face, not drawing the left side of a clock, not reading the left pages of a book, and not acknowledging anything or anyone in the left half of the room. Some will deny that their left arm and leg are theirs and will not use them when trying to get out of bed, even though they are not paralyzed. Some patients will even neglect the left side of space in their imagination and memories.3 That the deficits vary according to the size and location of the lesion suggests that damage that disrupts specific neural circuits results in impairments in different component processes.

When this was done on normal subjects, the brain answered back with the N400 brain wave response when the word was incongruous, but not when it was congruous.