How Are Aversive Memories Formed?

Treatments for anxiety disorders will remain nonspecific until scientists elucidate the cellular mechanisms by which fearfulness becomes associated with certain events and thoughts. A standard animal model of such associations is conditioned taste aversion (CTA), in which mice learn in a single trial to avoid rather than prefer saccharine; the trial involves pairing saccharine with intraperitoneal injection of lithium chloride to cause gastrointestinal distress. These investigators examined the role of the calcium-dependent protein phosphatase calcineurin in aversive learning and extinction of CTA (accomplished by repeatedly presenting saccharine without the noxious stimulus).

In wild-type mice, CTA was associated with reduced calcineurin ac…