When Ivan Pavlov’s dog heard the ding of a bell, the pup started salivating in anticipation of his dinner. When professor Mary Torregrossa’s rats heard a similar tone, they craved cocaine. At least, some of them did — before Torregrossa and her colleagues rewrote their memories.
Torregrossa studies the psychology of drug addiction and relapses at the University of Pittsburgh School of Medicine (where she is also an associate professor of psychiatry). In a new study published Jan. 22 in the journal Cell Reports, Torregrossa and two of her colleagues set up a Pavlovian experiment in which a group of lab rats came to associate a specific audiovisual cue with the rush of a cocaine infusion.
Eventually, merely seeing or hearing the cue made the rats crave more cocaine — until the researchers “erased” that association from the rats’ brains using a neural-stimulation technique called optogenetics. Suddenly, rats exposed to the same audiovisual cue that once made their brains glow with anticipation showed no interest in the cue at all.