same energy, electrical energy in the form of action potentials. That means that the quality of an experience depends on the part of the brain to which nerves deliver their action potentials (e.g., light from nerves arriving at the visual cortex and sound from nerves arriving at the auditory cortex). In 1945, Roger Sperry showed that it is the location in the brain to which nerves attach that determines experience. He studied amphibians whose optic nerves cross completely, so that the left eye connects to the right side of the brain and the right eye connects to the left side of the brain. He was able to cut the optic nerves and cause them to regrow on the opposite side of the brain so that the left eye now connected to the left side of the brain and the right eye connected to the right side of the brain. He then showed that these animals made the opposite movements from the ones they would have made before the operation. For example, before the operation, the animal would move to the left to get away from a large object approaching from the right. After the operation, the animal would move to the right in response to the same large object approaching from the right. Sperry showed similar results in other animals including mammals (rats), this work contributing to his Nobel Prize in 1981. References Norrsell U., Finger S. and Lajonchere C. (1999) Cutaneous sensory spots and the "law of specific nerve energies": history and development of ideas. Brain Research Bulletin, 48(5): 457-465. Sperry, R. W. (1945). Restoration of vision after crossing of optic nerves and after transplantation of eye. Journal of Neurophysiology, 8, 15-28. Uexküll, Jakob von (1947). Der Sinn des Lebens: Gedanken über die Aufgaben der Biologie. (Mitgeteilt in einer Interpretation der zu Bonn 1824 gehaltenen Vorlesung des Johannes Müller 'Von dem Bedürfnis der Physiologie nach einer philosophischen Naturbetrachtung', mit einem Ausblick von Thure von Uexküll.) Godesberg: Verlag Helmut Küpper. Sensory systems Biology theories