Most of the convergence rate between the Indian and Eurasian plate is assumed to be absorbed along a major basal thrust beneath the Himalaya, the Main Himalayan Thrust (MHT). Deformation along this basal thrust in combination with frontal accretion results in the formation of the upper crustal fold‐thrust belt. The role of the underthrusting Indian crust and its impact on the long‐term growth of the Himalaya are only poorly understood, partly due to the lack of high‐resolution seismic images of the crust. To improve the imaging of lithospheric structures, we developed a 3‐D migration scheme for receiver functions using seismic data from the temporary GANSSER network in Bhutan. Extending the 2‐D high‐frequency ray approximation and common conversion point stacking to 3‐D including linear phase weighting and a quality assessment, we reveal significant along‐strike differences in the lithospheric structure beneath Bhutan. In western Bhutan, the Moho geometry shows an increased dip south of the Higher Himalaya reaching almost 70 km depth thereafter, whereas in eastern Bhutan the Moho is almost subhorizontal at 50 km depth across our network. The appearance of distinct listric structures beneath the MHT indicates intracrustal deformation up to crustal imbrication down to the lower crust. We propose that these variations, in the crustal thickness and in intracrustal structures, influence the upper crustal kinematics of the Bhutan Himalayan orogeny and are primarily driven by an Indian mantle‐slab northwest of Bhutan, and its absence northeast of Bhutan.

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The instrumental record of Bhutan is characterized by a lower seismicity compared to other parts of the Himalayan arc. To understand this low activity and its impact on the seismic hazard, a seismic network was installed in Bhutan for 22 months between 2013 and 2014. Recorded seismicity, earthquake moment tensors and local earthquake tomography reveal along-strike variations in structure and crustal deformation regime. A thickened crust imaged in western Bhutan suggests lateral differences in stresses on the Main Himalayan Thrust (MHT), potentially affecting the interseismic coupling and deformation regime. Sikkim, western Bhutan and its foreland are characterized by strike-slip faulting in the Indian basement. Strain is particularly localized along a NW-SE striking mid-crustal fault zone reaching from Chungthang in northeast Sikkim to Dhubri at the northwestern edge of the Shillong Plateau in the foreland. The dextral Dhubri-Chungthang fault zone (DCF) causes segmentation of the Indian basement and the MHT between eastern Nepal and western Bhutan and connects the deformation front of the Himalaya with the Shillong Plateau by forming the western boundary of the Shillong block. The Kopili fault, the proposed eastern boundary of this block, appears to be a diffuse zone of mid-crustal seismicity in the foreland. In eastern Bhutan we image a seismogenic, flat portion of the MHT, which might be either related to a partially creeping segment or to increased background seismicity originating from the 2009 M W 6.1 earthquake. In western-central Bhutan clusters of micro-earthquakes at the front of the High-Himalayas indicate the presence of a mid-crustal ramp and stress buildup on a fully coupled MHT. The area bounded by the DCF in the west and the seismogenic MHT in the east has the potential for M7-8 earthquakes in Bhutan. Similarly, the DCF has the potential to host M7 earthquakes as documented by the 2011 Sikkim and the 1930 Dhubri earthquakes, which were potentially associated with this structure.

Cognitive decline is an unavoidable aspect of aging that impacts important behavioral and cognitive skills. Training programs can improve cognition, yet precise characterization of the psychological and neural underpinnings supporting different training programs is lacking. Here, we assessed the effect and maintenance (3-month follow-up) of 3-month music and visual art training programs on neuroelectric brain activity in older adults using a partially randomized intervention design. During the pre-, post-, and follow-up test sessions, participants completed a brief neuropsychological assessment. High-density EEG was measured while participants were presented with auditory oddball paradigms (piano tones, vowels) and during a visual GoNoGo task. Neither training program significantly impacted psychometric measures, compared to a non-active control group. However, participants enrolled in the music and visual art training programs showed enhancement of auditory evoked responses to piano tones that persisted for up to 3 months after training ended, suggesting robust and long-lasting neuroplastic effects. Both music and visual art training also modulated visual processing during the GoNoGo task, although these training effects were relatively short-lived and disappeared by the 3-month follow-up. Notably, participants enrolled in the visual art training showed greater changes in visual evoked response (i.e., N1 wave) amplitude distribution than those from the music or control group. Conversely, those enrolled in music showed greater response associated with inhibitory control over the right frontal scalp areas than those in the visual art group. Our findings reveal a causal relationship between art training (music and visual art) and neuroplastic changes in sensory systems, with some of the neuroplastic changes being specific to the training regimen.

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