The effects of regeneration on memory in planarians

Abstract

Planarians are an excellent invertebrate model choice to understand regeneration and the memory of stimulus-response behavior. Unlike vertebrate models, planarians have the unique ability to fully regenerate tissues after damage. Studies using planarians produce conflicting results regarding their ability to retain memory after regeneration. Our research aimed to determine the effects of regeneration as a whole as well as the effects of different regions of regeneration on a planarian's memory of a conditioned stimulus. Here we have demonstrated that regeneration has no significant effect on a planarian’s memory. On average, we determined that the non-dissected planarians recalled the conditioned stimulus more frequently, but there was no statistically significant effect on memory retention (p-value=0.143, one-tailed student's t-test). Of the regenerated planarians, the original heads recalled the conditioned stimulus more than the regenerated heads, but this difference in memory was not statistically significant (p-value=0.079, one-tailed student's t-test). Explanations for these findings require a deeper look into the mechanics of learning and retention in primitive organisms such as the planarian.