Cockroaches can be conditioned, scientists say
KNIGHT RIDDER NEWSPAPERS
SENDAI, Japan -- Life scientists at Tohoku University have confirmed conditioned reflexes in cockroaches, just like Pavlov's drooling dogs.
This is the first confirmation of the conditioned reflex in a creature other than a mammal. The findings were used to illustrate the insect's higher brain functions in the February issue of the British publication The Journal of Experimental Biology.
Associate professor Makoto Mizunami of Tohoku University Graduate School of Life Science in Sendai and his team sprayed peppermint odor on 3-centimeter-long American cockroaches, but found the nerve cells in the insects that control salivation were not activated in response.
The researchers did, however, confirm that the cockroaches' nervous system was activated by the peppermint odor, after the insects had been conditioned five times by spraying the peppermint odor two seconds before feeding them some sugar solution.
This effect persisted a day later, they added.
The conditioned reflex was confirmed by Russian physiologist Ivan Pavlov a century ago in an experiment on dogs. When dogs come across food, they begin drooling. The experiment showed that after the dogs had been conditioned to hear a bell just before they were fed, they drooled when they heard a bell, even if no food was present.