The adolescent frontal cortex shows stronger population-level encoding of information than the adult during a putative sensitive period
Adolescence is commonly claimed to be a sensitive period for brain development, but it is not clear how experience at this stage can have such strong impacts. We hypothesized that enhanced sensitivity to experience during adolescence may manifest as stronger encoding of task-related information in the dorsomedial prefrontal cortex (dmPFC). To enable optical access to task-related layer 2/3 neural activity in the developing mouse dmPFC, we imaged mice under a 2-photon microscope while they learned an auditory go/no-go task. We found adolescent mice (postnatal day P30-45) learned the task to criterion faster than adult mice (P60-75). When we compared neural activity in expert mice with comparable performance between the two age groups, we found that a similar fraction of single cells encoded task variables in the two groups. However, task information could be better decoded from the adolescent dmPFC population activity than the adult, even when we controlled for differences in head-fixed running. Adolescents also showed greater noise correlation than adults and shuffling to remove this noise correlation suggested noise correlation contributed to gain of function in adolescent compared to adult brain. We suggest a working model for adolescent brain function in which greater noise correlation supports greater capacity for distributed encoding of information driving, for better or for worse, increased sensitivity to experiences at this stage of life.