Shufflebrain

I suspect that most experimentalists suffer, from time to time, from what I call janitor-induced paranoia--the certainty that in the middle of the night the janitor, or someone, has exchanged the labels on the test tubes, cages, or salamander dishes. I certainly suffered a bad case of the syndrome while observing the behavior of members of the tiger/marble salamander experiments. I repeated the operations and got identical results. But my disbelief simply would not go away. I mean, here was a brain in a foreign head, plugged into the medulla of a different species--a brain with two medullas, no less. And yet the beast behaved like a normal salamander. And every time I checked for vision (with mirror images of worms), the animal showed me it could see, which meant that the transplanted brain could process visual perception delivered by the foreign eyes of its host. One Sunday morning I finally gave up, pickled some of these animals, and dissected their brain cases. There was no question about it. Each had two medullas, one plugged into the other. And I could trace the host's optic nerves into the transplanted brain. Even if Lashley had been our janitor, I would have been forced to conclude that shuffling the brain had not scrambled feeding.

This is a dissection of a tiger salamander larve whose brain had been amputated forward of the medulla and replaced by the entire brain--including the medulla--of a smaller, marble salamander larva. The donor brain is the deep gray structure between the specimen's eyes; the host's medulla is the large whitish trough behind the donor medulla. The behavior of these animals was identical to that of the controls in all discernible respects.

Even after the tiger-marble series of experiments, I still clung feebly to the hope of impugning hologramic theory by means of some ingenious anatomical transformation. I formulated this last-ditch working hypothesis: Assume, I said to myself, that the medulla is the seat of feeding programs. Suppose, furthermore, that the brain anterior to the medulla merely gives the animal consciousness and nothing else. Obviously an unconscious animal can't carry out an attack. Perhaps all a transplant did, then, was to awaken the creature and allow feeding programs in its medulla to come into play. Clearly, I needed another experiment. I had to eliminate feeding memories from the graft but at the same time revive the host. And so I turned to the frog.

Now the adult leopard frog is a notorious carnivore. Yet as a young tadpole it is a vegetarian. When the tadpole bothers a tubifex at all, it is only to suck algae and fungi from the worm's wriggling flanks.

I called the first member of this new series Punky. Punky the tadamander! He had the body of a salamander (Amblystoma punctatum), but the brain in front of his medulla had come into this world in the head of a Rana pipiens.

***

The most obvious question about Punky was whether or not a frog's brain would even connect, anatomically, with a salamander's medulla. But this question had to wait. To answer it for certain, I would have to kill Punky. Meanwhile, it was only my hunch that his new brain would reinstate overt behavior. If he ever came around, I'd actually have to observe him--with my own eyes--eat a worm in order to vindicate my hypothesis.

By seventeen days after surgery, Punky had fully regained his ability to stand and swim. Within a few days after that, he had become the liveliest animal in my colony. (Tadpoles are more active than salamanders.) He was blind, but his sonar and sense of touch were in splendid working order. When I dropped a pebble into his bowl, the "clink" would alert him and bring him swimming over immediately. And so would a newly presented tubifex worm.

But the worm was completely safe. Punky would inspect the squirming crimson thread for perhaps a minute or two. Then he would execute a crisp about-face! and swim away. And this continued for the next 68 days, while I virtually camped at the edge of his dish. A conscious, alert and responsive little fellow he remained throughout. But not once during that time did Punky even hint at an attack, despite the fact that a fresh worm was always available for the taking. Worms were now objects of lively curiosity, not of furious assault. If feeding programs existed in Punky's medulla, their presence would have to be accepted on the strength of divine revelation, not experimental fact. My last-ditch hypothesis failed the pragmatic test of truth: it didn't work.