The critical period hypothesis in SLA follows a "use it then lose it" approach, which dictates that as a person ages, excess neural circuitry used during L1 learning is essentially broken down. If these neural structures remained intact they would cost unnecessary metabolic energy to maintain.
The critical period hypothesis in SLA follows a "use it or lose it" strategy, implying that with age, unused neural connections from L1 learning gradually diminish. If these neural structures were to remain intact, they would demand unnecessary energy expenditure.