Adaptation to Delayed Force Perturbations in Reaching Movements

Adaptation to deterministic force perturbations during reaching movements was extensively studied in the last few decades. Here, we use this methodology to explore the ability of the brain to adapt to a delayed velocity-dependent force field. Two groups of subjects preformed a standard reaching experiment under a velocity dependent force field. The force was either immediately proportional to the current velocity (Control) or lagged it by 50 ms (Test). The results demonstrate clear adaptation to the delayed force perturbations. Deviations from a straight line during catch trials were shifted in time compared to post-adaptation to a non-delayed velocity dependent field (Control), indicating expectation to the delayed force field. Adaptation to force fields is considered to be a process in which the motor system predicts the forces to be expected based on the state that a limb will assume in response to motor commands. This study demonstrates for the first time that the temporal window of this prediction needs not to be fixed. This is relevant to the ability of the adaptive mechanisms to compensate for variability in the transmission of information across the sensory-motor system

Linear Systems Description

Introduction The systems approach is a widely used practice in modeling artificial as well as natural phenomena. Each process or sub-process is viewed as an input-output system, as described graphically in Fig.1. This approach is used extensively in engineering, for example in modeling electronic and mechanical systems and in chemical process description. In this chapter we describe this approach and its application to biological systems in general and the nervous system in particular. The systems approach can be used as a modeling tool to comprehend the function of the system and to produce a hypothetical model which can be tested in experiments. It is useful in describing and characterising experimental results, at times by relating the anatomical and physiological properties to the measured variables (see for example the muscle spindle transfer function, Houk 1963). Mathematical modeling of part of the neurological system can be used to study that and other parts by simula

Home-Based Rehabilitation: Enabling Frequent and Effective Training

Rehabilitation studies have recently demonstrated that the amount of time spent training is one of the most important factors in one’s ability to regain motor control. The methods employed need to be effective, but individuals need to spend significant amounts of time retraining. One of the most effective ways to enable more training time is for rehabilitation to occur in one’s home so individuals have adequate access to it and there is no cost associated with traveling to the clinic. There are several challenges that need to be overcome to make home rehabilitation more common; for example adapting the methods from the clinical setting to the home setting, ensuring safety, and providing motivation. This chapter outlines existing technologies for upper and lower limb rehabilitation and how they could be adapted for use in one’s home. Although many types of disabilities would benefit from home-based rehabilitation, this discussion will focus on traumatic brain injuries, specifically stroke related. Many of the methods that could be used at home for stroke would also have application for helping in other circumstances