Biomedical subjects

P G Morasso

Publications and source records attributed to P G Morasso.

4 recordsLinked to original sources

PubMed1999

Computational implications of modeling grasping as a form of (multiple-parallel) reaching.

Although it is true that the specific research on grasping has been dominated in recent years by the canonical transport + grip model originally formulated by Jeannerod (1984), still one can find in the research on reaching a number of links and anticipations to the new view on grasping made explicit by the authors of the target article. This paper reviews some of the relevant concepts and outlines a modeling framework that aims at biological plausibility.

Biomechanical Phenomena↗

PubMed1999

Can muscle stiffness alone stabilize upright standing?

A stiffness control model for the stabilization of sway has been proposed recently. This paper discusses two inadequacies of the model: modeling and empiric consistency. First, we show that the in-phase relation between the trajectories of the center of pressure and the center of mass is determined by physics, not by control patterns. Second, we show that physiological values of stiffness of the ankle muscles are insufficient to stabilize the body "inverted pendulum." The evidence of active mechanisms of sway stabilization is reviewed, pointing out the potentially crucial role of foot skin and muscle receptors.

Humans↗

PubMed1998

Neuromotor control in handwriting and drawing: introduction and overview.

In this introduction to the Special Issue on Neuromotor Control in Handwriting and Drawing, an overview is given of the themes and sub-themes covered by these proceedings of the eighth Biennial Conference of the International Graphonomics Society (IGS) on handwriting and other graphic tasks, held in Genoa, Italy, 24-28 August, 1997. Section overviews are given for Neuromuscular and Biophysical Models; Learning and Cognitive Models; and Neuropsychological Issues. Moreover, to guide researchers in the field, this introduction also provides a summary list of major publications following the preceding IGS conferences.

Art↗

PubMed1995

Human hand impedance characteristics during maintained posture.

The present paper examines human hand impedance characteristics, including inertia and viscosity as well as stiffness, in multi-joint arm movements. While a subject maintains a given hand location, small external disturbances are applied to his hand by a manipulandum. The corresponding force-displacement vectors are measured and sampled over time in order to estimate the hand impedance by means of a second-order linear model. The experimental results in different subjects and hand locations are summarized as follows: (1) the estimated inertia matrices of the human hand well agrees with computed values using a two-joint arm model, (2) spatial variations of the stiffness ellipses are consistent with the experimental results of Mussa-Ivaldi et al. (1985), (3) hand stiffness and viscosity increase with the grip force of the subject, and (4) viscosity and stiffness ellipses tend to have similar orientation. The accuracy of the impedance estimation method is validated with a mechanical spring-mass system with known parameters.

Adult↗