Time perception and delay discounting in the FMR1 knockout rat

There is substantial evidence for timing (time perception) abnormalities related to developmental disabilities, particularly autism spectrum disorder. These findings have been reported in humans and nonhuman preclinical models. Our research objective was to extend that work to a genetic knockout (KO) model of fragile X/developmental disability, the FMR1 KO rat. We also sought to test delay discounting in the model and assess potential relations between timing and choice behavior. Consistent with previous human and nonhuman work, we found reduced timing precision in the FMR1 KO rats. We also discovered significantly increased smaller, sooner reward choice in the FMR1 KO rats. Performance on the timing task appeared to be unrelated to performance on the choice task for both model and control rats. These results add to what has become increasingly clear: timing is disrupted in humans diagnosed with developmental disabilities and in nonhuman models designed to model developmental disabilities. Our findings are consistent with those of previous work and the first to our knowledge to show such effects in the FMR1 KO rat. We discuss the potential clinical implications and future directions surrounding potential "timing interventions" for individuals diagnosed with developmental disabilities.