During adolescence, the human brain undergoes significant transformations that enhance cognitive, socioemotional, and perceptual abilities. This developmental stage is characterized by changes in brain networks that support these skills, including the complex tasks of detecting, following, and comprehending speech signals amidst environmental noise and competing voices. Puberty marks the onset of adolescence, potentially creating a sensitive period for neuroplasticity, where experience shapes brain development. Hormonal changes during this time correlate with observable physical changes, marking distinct stages of puberty.

Our study aims to investigate how these correlates of puberty relate to detectable functional and structural brain changes that could contribute to the fine-tuning of speech perception in noise at adolescence. Our protocol will include high-density electroencephalography (EEG) to assess the maturation of cortical tracking of speech in noise and functional connectivity. Additionally, we will analyze changes in grey and white matter using diffusion MRI with the Neurite Orientation Dispersion and Density Imaging (NODDI) modeling technique, which will help us discern the specific mechanisms of neuroplasticity involved. To investigate metabolic mechanisms supporting functional and structural neuroplasticity, we estimate GABA and glutamate neurotransmitter concentration using magnetic resonance spectroscopy in cortical regions involved in speech-in-noise processing. Speech perception in noise will be evaluated behaviorally by means of the Coordinate Response Measure paradigm (CRM); together with cognitive and linguistic factors known to contribute to its development. We will recruit a group of pre- and a group of early/mid pubertal adolescents. Across groups, participants will be age- and sex-matched, in order to isolate the effects of puberty, allowing us to compare hormonal influences and pubertal stages. Our objective is to delineate the trajectory of typically developing adolescent brains in regions related to cognitive and perceptual processes involved in speech perception in noise.

We will present adult pilot data utilizing these metrics to illustrate our protocol and support our modeling framework. This research seeks to clarify the interplay between puberty, neuroplasticity, and speech processing abilities in adolescents, paving the way for future research on the implications of these changes for learning and social interaction during this critical developmental period.

Funding: ERC grant nº101076968.