Prefrontal Excitation/ Inhibition Balance Supports Adolescent Enhancements in Circuit Signal to Noise Ratio

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ABSTRACT
Animal and human postmortem studies provide evidence that processes underlying excitatory/inhibitory (E/I) balance in prefrontal cortex (PFC) increase through adolescence into adulthood reflecting unique neural plasticity believed to support the maturation of executive function into adulthood.Our previous work has found increases in MRSI derived measures of glutamatergic excitatory/GABAergic inhibitory (E/I) balance through adolescence that is in accord with EEG evidence of developmental decreases in the aperiodic exponent during resting state. Developmental attainment of E/I balance in PFC should lead to fine-tuning of cortical circuitry resulting in enhanced neural population synchronization suppressing large asynchronous spontaneous activity leading to increases in signal-to-noise ratio (SNR) that may underlie improvements and stabilization of executive function into adulthood. Here, we present findings from the auditory steady state response (ASSR) task, including a 40hz gamma-band inducing stimuli that reflects the interplay between GABAergic inhibitory neurons and excitatory pyramidal neurons, in the same participants with MRSI glutamate/GABA data and working memory performance. We hypothesized a developmental transition through adolescence from predominantly spontaneous to evoked activity in PFC indicating enhancements in SNR supporting improvements in executive function.