To induce brain plasticity in humans, we casted the dominant upper extremity for 2 weeks and tracked changes in functional connectivity using daily 30-min scans of resting-state functional MRI (rs-fMRI). Casting caused cortical and cerebellar regions controlling the disused extremity to functionally disconnect from the rest of the somatomotor system, while internal connectivity within the disused sub-circuit was maintained. Functional disconnection was evident within 48 h, progressed throughout the cast period, and reversed after cast removal. During the cast period, large, spontaneous pulses of activity propagated through the disused somatomotor sub-circuit. The adult brain seems to rely on regular use to maintain its functional architecture. Disuse-driven spontaneous activity pulses may help preserve functionally disconnected sub-circuits. © 2020 Elsevier Inc.
Newbold et al. induced human brain plasticity by casting the dominant arm for 2 weeks. Disused brain regions rapidly (<48 h) disconnected from the motor system and manifested large, spontaneous activity pulses. Maintaining the brain’s functional architecture may require regular use, and spontaneous activity pulses could serve as a substitute. © 2020 Elsevier Inc.