In this paper, we address the issue of learning and representing object grasp affordances. Our first aim is to organize and memorize, independently of grasp information sources, the whole knowledge that an agent has about the grasping of an object, in order to facilitate reasoning on grasping solutions and their likelihood of success. By grasp affordance, we refer to the the different ways to p...

A full-length zebrafish cDNA clone and a partial mouse cDNA clone similar to chick DM-GRASP were isolated and analyzed. The nucleotide sequence of the full-length zebrafish clone shares 54% identity, and predicts 39% amino acid identity, with chick DM-GRASP. The partial mouse clone shares 76% nucleotide identity, and predicts 76% amino acid identity, with chick DM-GRASP. The predicted proteins ...

In the present study we investigate age-related changes in hand preference for grasping and the influence of task demands on such preference. Children (2-11), young-adults (17-28) and older-adults (57-90) were examined in a grasp-to-eat and a grasp-to-construct task. The end-goal of these tasks was different (eat vs. construct) as was the nature of the task (unimanual vs. bimanual). In both tas...

In natural manipulation activities of daily living, actions for object grasping must respect several constraints for successful task completion. For example, grasping actions must satisfy at a minimum the reachability of grasp contacts on the object surface, collision avoidance with obstacles, as well as kinematic and strength limits of the hand. In challenging manipulation scenarios with high ...

OBJECTIVE This study examined the influence ofpencil grasp on handwriting legibility during both short and long writing tasks in 46fourth-grade students who were typically developing. Matched samples were used to controlfor variability. METHOD Regular classroom writing assignments were scoredfor word and letter legibility, and scores were compared using a mixed repeated-measures analysis of v...

Neural activity has been studied during reaching and grasping separately, yet little is known about their combined representation. To study the functional organization of reaching and grasping in the premotor cortex (PM), we trained two monkeys to reach in one of six directions and grasp one of three objects. During prehensile movements, activity of proximal (shoulder and elbow) muscles was mai...

When using precision grip to pick up objects, there are many possible pairs of grasp points that permit the thumb and index finger to exert opposed forces for secure grip. Previously, it was shown that individuals select grasp points so that the line between them (grasp axis) passes through or near the center of mass (CoM), thus minimizing the torque around the grasp axis during lifting. The ac...

A scheme for learning to grasp objects using visual information is presented. A system is considered that coordinates a parallel-jaw gripper (hand) and a camera (eye). Given an object, and considering its geometry, the system chooses grasping points, and performs the grasp. The system learns while performing grasping trials. For each grasp we store location parameters that code the locations of...

Grasping behaviors require the selection of grasp-relevant object dimensions, independent of overall object size. Previous neuroimaging studies found that the intraparietal cortex processes object size, but it is unknown whether the graspable dimension (i.e., grasp axis between selected points on the object) or the overall size of objects triggers activation in that region. We used functional m...

The execution of reach-to-grasp movements in order to interact with our environment is an important subset of the human movement repertoire. To coordinate such goal-directed movements, information about the relative spatial position of target and effector (in this case the hand) has to be continuously integrated and processed. Recently, we reported the existence of spatial representations in sp...