Abstract
The ability to learn to associate a certain cue with an abundant food source must be of great significance for insects living in constantly changing environments, where the availability of food sources varies with the seasons. I found that the cricket could associate an odor to water reward. Here I review recent progress on the olfactory learning capabilities of the crickets, which provide solid basis for future studies of neural mechanisms of olfactory learning and memory. I examined the odor learning ability of cricket in terms of the length of memory retention, memory storage capacity and context learning. Behavioral experiments clarified the followings: 1) Olfactory memory established in nymph was kept for life, but it could be re-written easily. 2) Crickets could associate seven pairs of odors to water reward simultaneously. 3) Crickets have a capability to select one of a pair of odors and to avoid the other in one context and to do the opposite in another context. In various animals, it has been demonstrated that memory can be divided into several distinct temporal phases, e.g. short-term memory and long-term memory. Behavioral and pharmacological experiments in crickets demonstrated that memory after olfactory conditioning could be divided into 4 different phases.
