Handedness results from complementary hemispheric dominance, not global hemispheric dominance: evidence from mechanically coupled bilateral movements

Abstract

Two contrasting views of handedness can be described as 1) complementary dominance, in which each hemisphere is specialized for different aspects of motor control, and 2) global dominance, in which the hemisphere contralateral to the dominant arm is specialized for all aspects of motor control. The present study sought to determine which motor lateralization hypothesis best predicts motor performance during common bilateral task of stabilizing an object (e.g., bread) with one hand while applying forces to the object (e.g., slicing) using the other hand. We designed an experimental equivalent of this task, performed in a virtual environment with the unseen arms supported by frictionless air-sleds. The hands were connected by a spring, and the task was to maintain the position of one hand while moving the other hand to a target. Thus the reaching hand was required to take account of the spring load to make smooth and accurate trajectories, while the stabilizer hand was required to impede the spring load to keep a constant position. Right-handed subjects performed two task sessions (right-hand reach and left-hand stabilize; left-hand reach and right-hand stabilize) with the order of the sessions counterbalanced between groups. Our results indicate a hand by task-component interaction such that the right hand showed straighter reaching performance whereas the left hand showed more stable holding performance. These findings provide support for the complementary dominance hypothesis and suggest that the specializations of each cerebral hemisphere for impedance and dynamic control mechanisms are expressed during bilateral interactive tasks. NEW & NOTEWORTHY We provide evidence for interlimb differences in bilateral coordination of reaching and stabilizing functions, demonstrating an advantage for the dominant and nondominant arms for distinct features of control. These results provide the first evidence for complementary specializations of each limb-hemisphere system for different aspects of control within the context of a complementary bilateral task.

Hindlimb motor responses to unilateral brain injury: spinal cord encoding and left-right asymmetry

“…Besides left–right differences in segmental reflexes ( Hultborn and Malmsten, 1983 a , b ; Malmsten, 1983 ; and this study), physiological, anatomical and molecular asymmetries in the spinal cord ( Bakalkin et al , 1980 ; Chazov et al , 1981 ; Bakalkin et al , 1986 ; Bakalkin and Kobylyansky, 1989 ; Nathan et al , 1990 ; de Kovel et al , 2017 ; Kononenko et al , 2017 ; Ocklenburg et al , 2017 ; Kononenko et al , 2018 ; Woytowicz et al , 2018 ) along with general lateralization of motor functions ( Sainburg, 2014 ; Sainburg et al , 2016 ; Knebel et al , 2018 ; Stancher et al , 2018 ) have been reported. Three-quarters of cervical spinal cords are asymmetric with larger right side ( Nathan et al , 1990 ).…”

Handedness Development: A Model for Investigating the Development of Hemispheric Specialization and Interhemispheric Coordination

“…Indeed, there are complementary specializations of each hemisphere for different aspects of the manual control involved in a role-differentiated bimanual manipulation (RDBMthe preferred hand holds the needle in sewing or the lid when unscrewing a jar, etc.) task (Woytowicz, Westlake, Whitall, & Sainburg, 2018). Again, these differences are relative, not absolute.…”

The probability of choosing both hands depends on an interaction between motor capacity and limb-specific control in chronic stroke

“…Instead, the left hand rested or "hovered", seemingly unable to disengage from its stabilization role. Recently, Woytowicz and colleagues (Woytowicz et al 2018) reported that switching preferred roles of the left and right hand during a simulated "bread-cutting" task was in fact non-optimal for motor performance. By examining relevant characteristics of the movement, they demonstrated that the right hand showed straighter reaching trajectories but was poor at stabilizing, whereas the left hand exhibited more stable holding performance, but was poor at reaching.…”