A Model of Cerebellar Adaptation of Grip Forces During Lifting
نویسندگان
چکیده
R We investigated adaptive neural control of precision grip forces during object lifting. A model is presented that adjusts reactive and anticipatory grip forces to a level just above that needed to stabilize lifted objects in the hand. The model obeys principles of cerebellar structure and function by using slip sensations as error signals to adapt phasic motor commands to tonic force generators associated with output synergies controlling grip aperture. The learned phasic commands arc weightand texture-dependent. Simulations of the new circuit model reproduce key aspects of experimental observations of force application. Over learning trials, the onset of grip force buildup comes to lead the load force buildup, and the rate~of-rise of grip force, but not load force, scales inversely with the friction of the gripped object.
منابع مشابه
Size-weight illusion, anticipation, and adaptation of fingertip forces in patients with cerebellar degeneration.
The smaller of two equally weighted objects is judged to be heavier when lifted (size-weight illusion [SWI]). In contrast, fingertip forces show an initial size effect but adapt to the true object weights within a few trials. The aim of this study was to investigate possible contributions of the cerebellum to SWI, force anticipation, and adaptation based on object size and weight. Eighteen part...
متن کاملEffect of blocking tactile information from the fingertips on adaptation and execution of grip forces to friction at the grasping surface.
Adaptation of fingertip forces to friction at the grasping surface is necessary to prevent use of inadequate or excessive grip forces. In the current study we investigated the effect of blocking tactile information from the fingertips noninvasively on the adaptation and efficiency of grip forces to surface friction during precision grasp. Ten neurologically intact subjects grasped and lifted an...
متن کاملCoordinated isometric muscle commands adequately and erroneously programmed for the weight during lifting task with precision grip
Small objects were lifted from a table, held in the air, and replaced using the precision grip between the index finger and thumb. The adaptation of motor commands to variations in the object's weight and sensori-motor mechanisms responsible for optimum performance of the transition between the various phases of the task were examined. The lifting movement involved mainly a flexion of the elbow...
متن کاملVisual and tactile information about object-curvature control fingertip forces and grasp kinematics in human dexterous manipulation.
Most objects that we manipulate have curved surfaces. We have analyzed how subjects during a prototypical manipulatory task use visual and tactile sensory information for adapting fingertip actions to changes in object curvature. Subjects grasped an elongated object at one end using a precision grip and lifted it while instructed to keep it level. The principal load of the grasp was tangential ...
متن کاملDeficits in sensorimotor control during precise hand movements in Huntington's disease.
OBJECTIVES To investigate the performance of patients with Huntington's disease (HD) while manipulating objects using a precision grip. METHODS The grip forces developed by the fingers were studied while subjects lifted an object of unpredictable weight in the hand. The ability to stabilize grip force after externally imposed weight change was also studied. RESULTS Patients used higher grip...
متن کامل