Lateralized functional connectivity of the sensorimotor cortex and its variations during complex visuomotor tasks

Previous studies have shown that the left hemisphere dominates motor function, often observed through homotopic activation measurements. Using a functional connectivity approach, this study investigated the lateralization of the sensorimotor cortex during handwriting and drawing, two complex visuomotor tasks with varying contextual demands. We found that both left- and right-lateralized connectivity in the primary motor cortex (M1), dorsal premotor cortex (PMd), somatosensory cortex, and visual regions were evident in adults (males and females), primarily in an inter-hemispheric integrative fashion. Critically, these lateralization tendencies remained highly invariant across task contexts, representing a task-invariant neural architecture for encoding fundamental motor programs consistently implemented in different task contexts. Additionally, the PMd exhibited a slight variation in lateralization degree between task contexts, reflecting the ability of the high-order motor system to adapt to varying task demands. However, connectivity-based lateralization of the sensorimotor cortex wasn't detected in 10-year-old children (males and females), suggesting that the maturation of connectivity-based lateralization requires prolonged development. In summary, this study demonstrates both task-invariant and task-sensitive connectivity lateralization in sensorimotor cortices that support the resilience and adaptability of skilled visuomotor performance. These findings align with the hierarchical organization of the motor system and underscore the significance of the functional connectivity-based approach in studying functional lateralization.Significance Statement Previous research has demonstrated the left-lateralized activation in the motor cortex, tailored to task demands. Nonetheless, functional connectivity lateralization of the motor cortex and its task-dependent variations across task contexts remain largely unknown. By employing a connectivity-based approach, this study unveils left- and right-lateralized connectivity in the sensorimotor cortex during complex visuomotor processing in adults. Importantly, these lateralized patterns exhibit unwavering stability throughout task contexts, with a nuanced degree of lateralization variation observed in the dorsal premotor cortex. While, middle-aged children lack similar connectivity lateralization, suggesting a prolonged development for connectivity lateralization. These results illuminate the connectivity lateralization features of the motor cortex, offering new insights into the neural underpinnings of the resilience and adaptability of motor skills.