Population-level encoding of task information is stronger in the adolescent compared to adult frontal cortex

Adolescence is commonly claimed to be a 'sensitive period,' but it is not clear how experience at this age may have stronger impact than in adulthood. 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 study neural activity in layer 2/3 of the developing mouse dmPFC, we used a microscope to image mice while they learned an auditory go/no-go task. We found adolescent mice (30-45 days old) learned the task to criterion faster than adult mice (60-75 days old). When we compared activity in expert mice with comparable performance between the two age groups, we found that a similar fraction of single cells encoded task variables. However, task information could be better decoded from the adolescent dmPFC population activity than the adult. 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 increased sensitivity to experiences at this stage of life.