Cortico-cerebellar network involved in saccade adaptation.

Saccade adaptation is the learning process that ensures that vision and saccades remain calibrated. The central nervous system network involved in these adaptive processes remains unclear because of difficulties in isolating the learning process from the correlated visual and motor processes. Here we imaged the human brain during a novel saccade adaptation paradigm that allowed us to isolate neural signals involved in learning independent of the changes in the amplitude of corrective saccades usually correlated with adaptation.

Posture-movement responses to stance perturbations and upper limb fatigue during a repetitive pointing task.

Localized muscle fatigue and postural perturbation have separately been shown to alter whole-body movement but little is known about how humans respond when subjected to both factors combined. Here we sought to quantify the kinematics of postural control and repetitive upper limb movement during standing surface perturbations and in the presence of fatigue. Subjects stood on a motion-based platform and repetitively reached between two shoulder-height targets until noticeably fatigued (rating of perceived exertion=8/10).

Time-dependent adaptations to posture and movement characteristics during the development of repetitive reaching induced fatigue.

Repetitive movements are common to many daily activities but often lead to the development of fatigue. We have previously shown that fatigue leads to changes in tridimensional spatial characteristics of the whole body. However, temporal aspects of these posture and movement adaptations have yet to be investigated.

Posture-movement changes following repetitive motion-induced shoulder muscle fatigue.

Repetitive motion-induced fatigue not only alters local motion characteristics but also provokes global reorganization of movement. However, the three-dimensional (3D) characteristics of these reorganization patterns have never been documented in detail. The goal of this study was to assess the effects of repetitive reaching-induced arm fatigue on the whole-body, 3D biomechanical task characteristics.

Age-related modifications in steering behaviour: effects of base-of-support constraints at the turn point.

This study investigated the effects of altering the base of support (BOS) at the turn point on anticipatory locomotor adjustments during voluntary changes in travel direction in healthy young and older adults. Participants were required to walk at their preferred pace along a 3-m straight travel path and continue to walk straight ahead or turn 40 degrees to the left or right for an additional 2-m. The starting foot and occasionally the gait starting point were adjusted so that participants had to execute the turn using a cross-over step with a narrow BOS or a lead-out step with a wide BOS.

Strategies used by older adults to change travel direction.

Introduction: A distinct body reorientation strategy during steering tasks has been reported in young adults. As challenges to whole-body stability in older adults occur when navigating complex environments, this study was designed to examine control strategies used by older adults to initiate a voluntary change in travel direction.

Methods: Thirteen older adults, recruited from an independent living division of a local retirement residence, were instrumented with reflective markers and whole-body kinematic data were monitored using a video camera (30 Hz).