Jerome Lettvin - Unusual Experiments

Unusual Experiments

vertebrate unmyelinated axons exhibit sub-millisecond triphasic spikes

action potentials found at myelinated nodes of Ranvier are altogether absent in Remak fibers

a cut optic nerve trained to the olfactory lobe regrows, remapping the retina

(Functional Properties of regenerated axons, Brain Research 1995)
senses appear to direct brain growth rather than the reverse

axonal stimulation backfires into the cell body

action potentials can travel from axons to the axon hillock and into the cell

stimulating the bulbo-reticular inhibitory system stops strychnine convulsions

reflexes have system-wide attenuation controls

axon pulse intervals can be separated into bands;

some form of information is encoded in pulse intervals

color constancy derives from boundaries and vertices imaged on the retina

(The Colors of Things, Scientific American 1986)
color is relational, not related to wavelength

images stationary on the retina fade to invisible

temporal or spatial transients are critical to vision

visible insects cause no nervous activity in a frog that sees a duck

attention obeys hierarchical rules

While working in the Marine Zoological Station in Naples, Italy, he had a 30-foot-long (9.1 m) room in which octopus holding tanks were kept, with fine mesh metal screens to keep them from escaping. One tank, at the far end, held his youngest son Jonathan's pet octopus named juvenile delinquent (JD). One day he teased JD with a stick. The next morning, his son and he came to the door and noticed a puddle under the door. Fearing the worst (broken tanks), he opened the door, and was greeted by a blast of water in his face (but not his son's face). From across the room, and through the screen, JD had perfect aim, after which he jetted to the bottom of the tank, inked it up, and hid for the rest of the day. Still confused about the water under the door, Lettvin looked at the back of the door and saw a spot of water at the height of his face. JD had been practicing for revenge. From this and other experiences, Lettvin concluded that octopodes are highly intelligent, and from that time on he never ate octopus again, out of respect for octopodes as colleagues.

Later repeated by a pair of Russian scientists, Lettvin demonstrated that a headless cat retains all of its normal functions like standing, scratching an itch, walking on a treadmill, and adjusting posture to prevent falling over.