Temporal Development of Anticipatory Reflex Modulation to Dynamical Interactions During Arm Movement

Abstract

Kimura T, Gomi H. Temporal development of anticipatory reflex modulation to dynamical interactions during arm movement. J Neurophysiol 102: 2220 -2231, 2009. First published August 5, 2009 doi:10.1152/jn.90907.2008. It is known that somatosensory reflex during voluntary arm movement is modulated anticipatorily according to given tasks or environments. However, when and how reflex amplitude is set remains controversial. Is the reflex modulation completed preparatorily before movement execution or does it vary with the movement? Is the reflex amplitude coded in a temporal manner or in a spatial (or state-dependent) manner? Here we studied these issues while subjects performed planar reaching movements with upcoming opposite (rightward/leftward) directions of force fields. Somatosensory reflex responses of shoulder muscles induced by a small force perturbation were evaluated at several points before the arm encountered predictable force fields after movement start. We found that the shoulder flexor reflex responses were generally higher for the rightward than for the leftward upcoming force fields, whereas the extensor reflex responses were higher for the leftward force field. This reflex amplitude depending on the upcoming force field direction became prominent as the reflex was evoked closer to the force fields, indicating continuous changes in reflex modulation during movement. An additional experiment further showed that the reflex modulation developed as a function of the temporal distance to the force fields rather than the spatial distance. Taken together, the results suggest that, in the force field interaction task, somatosensory reflex amplitude during the course of movement is set anticipatorily on the basis of an estimate of the time-to-contact rather than the state-to-contact, to upcoming dynamical interaction during voluntary movement.

Contributions of the cerebellum and the motor cortex to acquisition and retention of motor memories

“…While there are many factors that can affect kinematic performance in field trials, including changes in muscle co-contraction (Thoroughman and Shadmehr, 1999), and changes in the gain of the long-latency sensory feedback pathways (Kimura et al, 2006; Kimura and Gomi, 2009; Ahmadi-Pajouh et al, 2012), in error-clamp trials these factors are eliminated. Forces that participants produce in error-clamp trials are a proxy for a model that the brain constructs, associating state of the limb to expected perturbation forces (Hwang and Shadmehr, 2005; Sing et al, 2009).…”

Modulation of error-sensitivity during a prism adaptation task in people with cerebellar degeneration

“…This may be critically important, since movement trajectory is affected both by the ability of the nervous system to learn from errors that were observed in the previous trials, termed trial-to-trial learning, and respond to errors that are sensed in the current trial, termed within-trial response to error (Ahmadi-Pajouh et al 2012;Franklin et al 2007;Kimura et al 2006;Kimura and Gomi 2009;Wong et al 2009). Some studies suggest that the human motor cortex may play an important role in learning to modulate the within-trial response to error (Kimura et al 2006), although disruption of the human cerebellum also reduces the gain of this feedback pathway (Herzfeld et al 2014a).…”

Contribution of intracortical inhibition in voluntary muscle relaxation

“…Precise temporal modulation of muscle activity and associated limb force is necessary for many daily activities such as object manipulation (Kutz et al 2007;Moerchen et al 2007) and reaching (Kimura and Gomi 2009). Delays in initiation or termination of muscle activity can lead to inefficient grip force scaling during grip-and-lift tasks (Nowak et al 2003(Nowak et al , 2007 and poor timing and coordination of movement (Nowak et al 2007).…”