Comparison between macaques’ and humans’ kinematics of prehension: the role of morphological differences and control mechanisms

Abstract

Reaching and grasping has been widely studied in both macaques and humans, mainly with the aim of finding similar patterns of behavior in the two species. Little attention has yet been given to how morphological and behavioral differences between the two species might affect the kinematics of the movement. In this study, we present a careful analysis of the similarities and differences between humans' and macaques' prehension movements and discuss these with respect to both the control system and the biomechanics of the arm. Five humans and five macaques performed the same task, namely grasping small feeding objects using a precision grip. Macaques were observed in unconstrained conditions, free to adjust their body posture. The behavioral protocol for macaques revealed a postural preference for sitting and keeping the elbow slightly flexed when applying a precision grip. In agreement with the literature, kinematics revealed general features of movement common to both humans and macaques. However, within a similar timeframe, macaques produced steeper and wider excursion of the elbow and of the wrist, smaller abduction of the shoulder joint and larger displacement of the torso than humans did. The three-joint limb revealed stronger irregularities for the macaques. We hypothesize that the larger kinematic irregularities and the specific elbow--shoulder posture in macaques result in part from an effort of the control system to compensate for different biomechanical constraints, namely for limited shoulder-joint excursion, in order to achieve a similar range of comfort of motion. Finally, we briefly consider the influence of primitive neural circuits responsible for arm motion during locomotion and speculated on their influence on the control of reaching in macaques.

Movement curvature planning through force field internal models

“…The idea that embodiment can be encapsulated in the control system itself is in line with our earlier observation that differences in the kinematic features of reaching movements in macaques and humans could be related to the biomechanical properties of the macaques' and humans' shoulder joints (Christel and Billard 2002). Importantly, the model proposed here is not limited to self-oriented movements and can be applied to any point-to-point reaching movement such as for example reaching to targets in the extrapersonal frontal workspace.…”

Functional Magnetic Resonance Imaging Reveals the Neural Substrates of Arm Transport and Grip Formation in Reach-to-Grasp Actions in Humans

“…Second, the difference may reflect a functional difference between the two species. Specifically, macaques typically use their arms for locomotion (quadrupedal walking and climbing) as well as grasping, leading to morphological and functional differences in reaching and grasping (Christel and Billard, 2002). Moreover, although macaques can perform precision grips, with the thumb opposing the side of the index finger, they typically do so with less frequency and dexterity than humans, who grasp with the thumb opposing the pad of the index finger (Spinozzi et al, 2004;Macfarlane and Graziano, 2009).…”

The Neuroscience of Vision-Based Grasping: A Functional Review for Computational Modeling and Bio-Inspired Robotics

“…Differences in control strategies depend also on structure, morphology and kinematics of body and limbs, and it is therefore very difficult to draw a full interspecies parallel [30]. The current evidence suggests that the human intraparietal cortex is more complex, and contains visuospatial processing areas that are not present, or much reduced, in monkeys [74,122].…”