Gating of Somatosensory Neural Oscillations Across the Lifespan: A Narrative Review.
Healthy and pathological aging are associated with progressive changes in cortical inhibition, yet the underlying neural mechanisms remain incompletely understood. Somatosensory gating (SG), the brain's suppression of redundant tactile input, provides a pre-attentive marker of inhibitory function. Paired-pulse paradigms concurrent with noninvasive magnetoencephalography (MEG) provide a millisecond portrayal of the neural dynamics underlying somatosensory processing and the gating of such responses with excellent spatial resolution. This narrative review synthesizes SG research focusing on neural oscillations, with a particular emphasis on gamma-band activity which is linked to GABAergic inhibitory processes. SG oscillatory metrics are sensitive to both healthy chronological aging and biological stressors such as allostatic load and epigenetic aging and offer insight beyond neural evoked responses. We also examine aberrant presentations of SG oscillatory metrics in age-related neuropathologies, including Alzheimer's disease and HIV-associated neurocognitive disorder, sensorimotor pathologies, and psychiatric conditions. Finally, we outline methodological considerations and propose future directions to refine SG oscillatory metrics as markers of inhibitory decline or potential compensatory mechanisms, situating the existing findings within prominent theories of neurocognitive aging. Collectively, this review underscores how an oscillatory perspective to brain function reveals frequency-specific somatosensory and inhibitory mechanisms, highlighting their differential sensitivity to healthy aging and pathology.