Language, praxis, and the right hemisphere: clues to some mechanisms of consciousness.

The linguistic capacity of each separate cerebral hemisphere was examined in a 15-year-old, callosally sectioned, normally right-handed male. The results demonstrated that while the right hemisphere was not capable of expressive speech, it could comprehend nouns and verbs, and also possessed the motor engrams necessary to carry out verbal and pictorial commands. In addition, the mute hemisphere was found to be capable of spelling the names of visually presented items by arranging letters as well as by writing with the left hand. Finally, the manner in which the left hemisphere dealt with the overt bodily response to commands presented to the right hemisphere suggested clues to what we feel are mechanisms by which a personal sense of conscious reality is created in the normal brain.