Recently, Criscimagna-Hemminger et al. (2003) reported a pattern of generalization of force-field adaptation between arms that differs from the pattern that occurs across different configurations of the same arm. Although the intralimb pattern of generalization points to an intrinsic encoding of dynamics, the interlimb transfer described by these authors indicates that information about force is represented in a frame of reference external to the body. In the present study, subjects adapted to a viscous curl-field in two experimental conditions. In one condition, the field was introduced suddenly and produced clear deviations in hand paths; in the second condition, the field was introduced gradually so that at no point during the adaptation process could subjects observe or did they have to correct for a substantial kinematic error. In the first case, a pattern of interlimb transfer consistent with Criscimagna-Hemminger et al. (2003) was observed, whereas no transfer of learning between limbs occurred in the second condition. The findings suggest that there is limited transfer of fine compensatory-force adjustment between limbs. Transfer, when it does occur, may be primarily the result of a cognitive strategy that arises as a result of the sudden introduction of load and associated kinematic error.

Abs~uct:The authors develop a functional linear model in which the values at time t of a sample of curves y, ( t ) are explained in a feed-forward sense by the values of covariate curves 2 , (s) observed at times s 5 t. They give special attention to the case s f [t -6, t]. where the lag parameter 6 is estimated from the data. They use the finite element method to estimate the bivariate parameter regression function p(s, t), which is defined on the triangular domain s 5 t . They apply their model to the problem of predicting the acceleration of the lower lip during speech on the basis of electromyographical recordings from a muscle depressing the lip. They also provide simulation results to guide the calibration of the fitting process.Le rnodhle lineaire fonctionnel historique Rt?sumt? : Les auteurs dbcrivent un modble linbaire fonctionnel dans lequel les valeurs au temps t d'un Cchantillon de courbes y, ( t ) sont expliqubes par les valeurs observbes aux temps s 5 t de courbes covariables z,(s). Ils accordent une attention particulibre au cas oh s E [t -6, t ] , 6 repdsentant un parambtre de dtlai estimb ?i partir des donnbes. ns emploient la mbthode des tl6ments finis pour estimer la fonction parambtre p ( s , t) bivaribe dbfinie sur le domaine triangulaire s 5 t. Ils appliquentleur modble ? i la pdvision de courbes d'accblbration de la lbvre infbrieure d'un locuteur partir d'enregistrements blectromyographiques d'un muscle abaissant celle-ci. Ils pdsentent aussi des dsultats de simulation pouvant guider le processus de calibration intervenant dans l'ajustement du modble.

In a recent study, Tan et al. (2014a,b) showed that the increase in ␤-power typically observed after a movement above sensorimotor regions (␤-rebound) is attenuated when movement-execution errors are induced by visual perturbations. Moreover, akin to sensorimotor adaptation, the effect depended on the context in which the errors are experienced. Thus the ␤-rebound attenuation might relate to neural processes involved in trial-to-trial adaptive mechanisms. In two EEG experiments with human participants, along with the ␤-rebound, we examine ␤-activity during the preparation of reaches immediately following perturbed movements. In the first experiment, we show that both foreperiod and postmovement ␤-activities are parametrically modulated by the sizes of kinematic errors produced by unpredictable mechanical perturbations (force field) independent of their on-line corrections. In the second experiment, we contrast two types of reach errors: movement-execution errors that trigger trial-to-trial adaptive mechanisms and goal errors that do not elicit sensorimotor adaptation. Movement-execution errors were induced by mechanical or visual perturbations, whereas goal errors were caused by unexpected displacements of the target at movement initiation. Interestingly, foreperiod and postmovement ␤-activities exhibit contrasting patterns, pointing to important functional differences of their underlying neuronal activity. While both types of reach errors attenuate the postmovement ␤-rebound, only the kinematic errors that trigger trial-to-trial motor-command updates influenced ␤-activity during the foreperiod. These findings suggest that the error-related modulation of the ␤-rebound may reflect salience processing, independent of sensorimotor adaptation. In contrast, modulations in the foreperiod ␤-power might relate to the motorcommand adjustments activated after movement-execution errors are experienced.