Aging alters the functional connectivity of motor theta networks during sensorimotor reactions

Abstract

ObjectiveBoth cognitive and primary motor networks alter with advancing age in humans. The networks activated in response to external environmental stimuli supported by theta oscillations remain less well explored. The present study aimed to characterize the effects of aging on the functional connectivity of response-related theta networks during sensorimotor tasks. MethodsElectroencephalographic signals were recorded in young and middle-to-old age adults during three tasks performed in two modalities, auditory and visual: a simple reaction task, a Go-NoGo task, and a choice-reaction task. Response-related theta oscillations were computed. The phase-locking value (PLV) was used to analyze the spatial synchronization of primary motor and motor control theta networks. ResultsPerformance was overall preserved in older adults. Independently of the task, aging was associated with reorganized connectivity of the contra-lateral primary motor cortex. In young adults, it was synchronized with motor control regions (intra-hemispheric premotor/frontal and medial frontal). In older adults, it was only synchronized with intra-hemispheric sensorimotor regions. ConclusionsMotor theta networks of older adults manifest a functional decoupling between the response-generating motor cortex and motor control regions, which was not modulated by task variables. The overall preserved performance in older adults suggests that the increased connectivity within the sensorimotor network is associated with an excessive reliance on sensorimotor feedback during movement execution compensating for a deficient cognitive regulation of motor regions during sensorimotor reactions. HighlightsO_LIThe connectivity of motor theta networks is modulated by sensory and cognitive variables in sensorimotor tasks. C_LIO_LIMotor theta oscillations of young adults are synchronized between the primary motor cortex and cognitive control regions. C_LIO_LIIn contrast, motor theta networks of older adults are decoupled from motor control regions during sensorimotor reactions. C_LI