Maturation of striatal dopamine supports the development of habitual behavior through adolescence.

Developmental trajectories during the transition from adolescence to adulthood contribute to the establishment of stable, adult forms of operation. Understanding the neural mechanisms underlying this transition is crucial for identifying variability in normal development and the onset of psychiatric disorders, which typically emerge during this time. Habitual behaviors can serve as a model for understanding brain mechanisms underlying the stabilization of adult behavior, while also conferring risk for psychopathologies.

Adolescent maturation of dorsolateral prefrontal cortex glutamate:GABA and cognitive function is supported by dopamine-related neurobiology.

Developmental changes in prefrontal cortex (PFC) excitatory (glutamatergic, Glu) and inhibitory (gamma- aminobutryic acid, GABA) neurotransmitter balance (E:I) have been identified during human adolescence, potentially reflecting a critical period of plasticity that supports the maturation of PFC-dependent cognition. Animal models implicate increases in dopamine (DA) in regulating changes in PFC E:I during critical periods of development, however, mechanistic relationships between DA and E:I have not been studied in humans. Here, we used high field (7T) echo planar imaging (EPI) in combination with Magnetic Resonance Spectroscopic Imaging (MRSI) to assess the role of basal ganglia tissue iron-reflecting DA neurophysiology-in longitudinal trajectories of dorsolateral PFC Glu, GABA, and their relative levels (Glu:GABA) and working memory performance from adolescence to adulthood in 153 participants (ages 10-32 years old, 1-3 visits, 272 visits total).

Prefrontal excitation/inhibition balance supports adolescent enhancements in circuit signal to noise ratio.

The development and refinement of neuronal circuitry allow for stabilized and efficient neural recruitment, supporting adult-like behavioral performance. During adolescence, the maturation of PFC is proposed to be a critical period (CP) for executive function, driven by a break in balance between glutamatergic excitation and GABAergic inhibition (E/I) neurotransmission. During CPs, cortical circuitry fine-tunes to improve information processing and reliable responses to stimuli, shifting from spontaneous to evoked activity, enhancing the SNR, and promoting neural synchronization.

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

The development and refinement of neuronal circuitry allow for stabilized and efficient neural recruitment, supporting adult-like behavioral performance. During adolescence, the maturation of PFC is proposed to be a critical period (CP) for executive function, driven by a break in balance between glutamatergic excitation and GABAergic inhibition (E/I) neurotransmission. During CPs, cortical circuitry fine-tunes to improve information processing and reliable responses to stimuli, shifting from spontaneous to evoked activity, enhancing the SNR, and promoting neural synchronization.

Aperiodic EEG and 7T MRSI evidence for maturation of E/I balance supporting the development of working memory through adolescence.

Adolescence has been hypothesized to be a critical period for the development of human association cortex and higher-order cognition. A defining feature of critical period development is a shift in the excitation: inhibition (E/I) balance of neural circuitry, however how changes in E/I may enhance cortical circuit function to support maturational improvements in cognitive capacities is not known. Harnessing ultra-high field 7 T MR spectroscopy and EEG in a large, longitudinal cohort of youth (N = 164, ages 10-32 years old, 347 neuroimaging sessions), we delineate biologically specific associations between age-related changes in excitatory glutamate and inhibitory GABA neurotransmitters and EEG-derived measures of aperiodic neural activity reflective of E/I balance in prefrontal association cortex.