Working memory is central to the execution of many daily functions and is typically divided into three phases: encoding, maintenance, and retrieval. While working memory performance has been repeatedly shown to decline with age, less is known regarding the underlying neural processes. We examined age‐related differences in the neural dynamics that serve working memory by recording high‐density magnetoencephalography (MEG) in younger and older adults while they performed a modified, high‐load Sternberg working memory task with letters as stimuli. MEG data were evaluated in the time‐frequency domain and significant oscillatory responses were imaged using a beamformer. A hierarchical regression was performed to investigate whether age moderated the relationship between oscillatory activity and accuracy on the working memory task. Our results indicated that the spatiotemporal dynamics of oscillatory activity in language‐related areas of the left fronto‐temporal cortices were similar across groups. Age‐related differences emerged during early encoding in the right‐hemispheric homologue of Wernicke's area. Slightly later, group differences emerged in the homologue of Broca's area and these persisted throughout memory maintenance. Additionally, occipital alpha activity during maintenance was stronger, occurred earlier, and involved more cortical tissue in older adults. Finally, age significantly moderated the relationship between accuracy and neural activity in the prefrontal cortices. In younger adults, as prefrontal activity decreased, accuracy tended to increase. Our results are consistent with predictions of the compensation‐related utilization of neural circuits hypothesis (CRUNCH). Such differences in the oscillatory dynamics could reflect compensatory mechanisms, which would aid working memory performance in older age. Hum Brain Mapp 37:2348–2361, 2016.

Sensory gating is a neurophysiological process whereby the response to a second stimulus in a pair of identical stimuli is attenuated, and it is thought to reflect the capacity of the CNS to preserve neural resources for behaviorally relevant stimuli. Such gating is observed across multiple sensory modalities and is modulated by age, but the mechanisms involved are not understood. In this study, we examined somatosensory gating in 68 healthy adults using magnetoencephalography (MEG) and advanced oscillatory and time-domain analysis methods. MEG data underwent source reconstruction and peak voxel time series data were extracted to evaluate the dynamics of somatosensory gating, and the impact of spontaneous neural activity immediately preceding the stimulation. We found that gating declined with increasing age and that older adults had significantly reduced gating relative to younger adults, suggesting impaired local inhibitory function. Most importantly, older adults had significantly elevated spontaneous activity preceding the stimulation, and this effect fully mediated the impact of aging on sensory gating. In conclusion, gating in the somatosensory system declines with advancing age and this effect is directly tied to increased spontaneous neural activity in the primary somatosensory cortices, which is likely secondary to age-related declines in local GABA inhibitory function.