Differences in Neurological Connectivity Between Right and Left Limb Dominant Individuals in Implicit Motor Sequence Learning

Abstract

Background: The majority of the global population identifies as right-hand dominant (RHD), while only about 11% of the population identifies as left-hand dominant (LHD) (Papadatou-Pastou et al, 2020) However, this population still makes up a large portion of the United States, and there is not currently much literature regarding the motor control differences between RHD and LHD individuals. Recent research findings revealed both neurological and behavioral differences between these populations, as each group had fundamental differences in their approach to skill acquisition. This information disproves the theory that each hemisphere of the brain controls the opposite side of the body. Methods: Participants (N=30; 15 LHD and 15 RHD) performed a random, but repetitive 13-element sequencing task with their dominant hand. Participants were not told of the repeating sequence. Brain activity was recorded using EEG. Four white rectangles were on a screen. When one rectangle turns black, the participant would press the corresponding button on a keypad. EEG activation patterns were compared across RHD and LHD individuals, and behavior was assessed by the rate of error reductions during the task. After completing data acquisition, the focus shifted to data processing, with a focus on advanced connectivity measurements. Results: RHD and LHD individuals are indistinguishable in terms of behavior and voltage, but when you look at how the brain is performing the task, LHD and RHD individuals have very different patterns of communication across the brain. RHD individuals were more unilateral in their communication process and relied mainly on the left hemisphere of the brain while, LHD individuals relied heavily on both hemispheres of the brain while performing the motor sequencing task. Conclusions: Brain lateralization is not entirely accurate for LHD individuals. Future rehabilitation therapies can be built off of these newfound neurological circuits and this research can be used to update scientific textbooks and later translated to improved clinical care for LHD individuals.