Assisted Cycle Therapy (ACT) Improved Self-Efficacy and Exercise Perception in Middle-Age Adults with Down Syndrome.

Alzheimer's disease is prevalent in persons with Down syndrome (DS) as early as their 30s and presents as decreased social interaction, coordination, and physical activity. Therefore, changing attitudes and beliefs about exercise is key to increasing motivation for physical activity especially in middle-age adults with DS. The aim of this study was to examine the effects of Assisted Cycle Therapy (ACT) on self-efficacy and exercise perception in middle-age adults with Down syndrome (DS) following an exercise intervention three times a week for 8 weeks.

Delay of gaze fixation during reaching movement with the non-dominant hand to a distant target.

The present study examined the effects of hand and task difficulty on eye-hand coordination related to gaze fixation behavior (i.e., fixating a gaze to the target until reach completion) in single reaching movements.

A condition that produces sensory recalibration and abolishes multisensory integration.

We examined the influence of extended exposure to a visuomotor rotation, which induces both motor adaptation and sensory recalibration, on (partial) multisensory integration in a cursor-control task. Participants adapted to a 30° (adaptation condition) or 0° (control condition) visuomotor rotation by making center-out movements to remembered targets. In subsequent test trials of sensory integration, they made center-out movements with variable visuomotor rotations and judged the position of hand or cursor at the end of these movements.

Effects of auditory feedback on movements with two-segment sequence and eye-hand coordination: Using a short auditory contact cue.

During sequential reaches to multiple targets, eye and hand movements are highly coordinated, and the gaze is anchored to each target until the reaching hand makes contact to each of them. Such contact events are monitored by multimodal (visual, proprioceptive) sensory systems, and one function of the gaze anchoring to each target is verification of successful target contact (reach completion). The present study focused on this verification function and examined how planning and control of eye and hand movements during two-segment eye-hand movements are affected by augmented auditory feedback of reach completion.

Visual and proprioceptive recalibrations after exposure to a visuomotor rotation.

Adaptation to a visuomotor rotation in a cursor-control task is accompanied by proprioceptive recalibration, whereas the existence of visual recalibration is uncertain and has even been doubted. In the present study, we tested both visual and proprioceptive recalibration; proprioceptive recalibration was not only assessed by means of psychophysical judgments of the perceived position of the hand, but also by an indirect procedure based on movement characteristics. Participants adapted to a gradually introduced visuomotor rotation of 30° by making center-out movements to remembered targets.

Effects of Hand and Hemispace on Multisensory Integration of Hand Position and Visual Feedback.

The brain generally integrates a multitude of sensory signals to form a unified percept. Even in cursor control tasks, such as reaching while looking at rotated visual feedback on a monitor, visual information on cursor position and proprioceptive information on hand position are partially integrated (sensory coupling), resulting in mutual biases of the perceived positions of cursor and hand. Previous studies showed that the strength of sensory coupling (sum of the mutual biases) depends on the experience of kinematic correlations between hand movements and cursor motions, whereas the asymmetry of sensory coupling (difference between the biases) depends on the relative reliabilities (inverse of variability) of hand-position and cursor-position estimates (reliability rule).

Effects of auditory feedback on movements with two-segment sequence and eye-hand coordination.

The present study investigated the effect of auditory feedback on planning and control of two-segment reaching movements and eye-hand coordination. In particular, it was examined whether additional auditory information indicating the progression of the initial reach (i.e.

Dissociating explicit and implicit measures of sensed hand position in tool use: Effect of relative frequency of judging different objects.

In a cursor-control task, the sensed positions of cursor and hand are biased toward each other. We previously found different characteristics of implicit and explicit measures of the bias of sensed hand position toward the position of the cursor, suggesting the existence of distinct neural representations. Here we further explored differences between the two types of measure by varying the proportions of trials with explicit hand-position (H) and cursor-position (C) judgments (C20:H80, C50:H50, and C80:H20).

Contrasting effects of adaptation to a visuomotor rotation on explicit and implicit measures of sensory coupling.

We previously investigated sensory coupling of the sensed positions of cursor and hand in a cursor-control task and found differential characteristics of implicit and explicit measures of the bias of sensed hand position toward the position of the cursor. The present study further tested whether adaptation to a visuomotor rotation differentially affects these two measures. Participants made center-out reaching movements to remembered targets while looking at a rotated feedback cursor.

Eye-hand coordination during visuomotor adaptation: effects of hemispace and joint coordination.

We previously examined adaptive changes of eye-hand coordination during learning of a visuomotor rotation. Gazes during reaching movements were initially directed to a feedback cursor in early practice, but were gradually shifted toward the target with more practice, indicating an emerging gaze anchoring behavior. This adaptive pattern reflected a functional change of gaze control from exploring the cursor-hand relation to guiding the hand to the task goal.

Eye-Hand Coordination during Visuomotor Adaptation with Different Rotation Angles: Effects of Terminal Visual Feedback.

This study examined adaptive changes of eye-hand coordination during a visuomotor rotation task under the use of terminal visual feedback. Young adults made reaching movements to targets on a digitizer while looking at targets on a monitor where the rotated feedback (a cursor) of hand movements appeared after each movement. Three rotation angles (30°, 75° and 150°) were examined in three groups in order to vary the task difficulty.

Effects of Reliability and Global Context on Explicit and Implicit Measures of Sensed Hand Position in Cursor-Control Tasks.

In a cursor-control task in which the motion of the cursor is rotated randomly relative to the movement of the hand, the sensed directions of hand and cursor are mutually biased. In our previous study, we used implicit and explicit measures of the bias of sensed hand direction toward the direction of the cursor and found different characteristics. The present study serves to explore further differences and commonalities of these measures.

Eye-hand coordination during visuomotor adaptation with different rotation angles.

This study examined adaptive changes of eye-hand coordination during a visuomotor rotation task. Young adults made aiming movements to targets on a horizontal plane, while looking at the rotated feedback (cursor) of hand movements on a monitor. To vary the task difficulty, three rotation angles (30°, 75°, and 150°) were tested in three groups.

Gaze locations affect explicit process but not implicit process during visuomotor adaptation.

The role of vision in implicit and explicit processes involved in adaptation to novel visuomotor transformations is not well-understood. We manipulated subjects' gaze locations through instructions during a visuomotor rotation task that established a conflict between implicit and explicit processes. Subjects were informed of a rotated visual feedback (45° counterclockwise from the desired target) and instructed to counteract it by using an explicit aiming strategy to the neighboring target (45° clockwise from the target).

Segment interdependency and gaze anchoring during manual two-segment sequences.

This study examined two-segment pointing movements with various accuracy constraints to test whether there is segment interdependency in saccadic eye movements that accompany manual actions. The other purpose was to examine how planning of movement accuracy and amplitude for the second pointing influences the timing of gaze shift to the second target at the transition between two segments. Participants performed a rapid two-segment pointing task, in which the first segment had two target sizes, and the second segment had two target sizes and two movement distances.

Coordination deficits during trunk-assisted reach-to-grasp movements in Parkinson's disease.

The present study investigated how Parkinson's disease (PD) affects temporal coordination among the trunk, arm, and fingers during trunk-assisted reach-to-grasp movements. Seated participants with PD and healthy controls made prehensile movements. During the reach to the object, the involvement of the trunk was altered based on the instruction; the trunk was not involved, moved forward (flexion), or moved backward (extension) in the sagittal plane.

Implicit and explicit representations of hand position in tool use.

Understanding the interactions of visual and proprioceptive information in tool use is important as it is the basis for learning of the tool's kinematic transformation and thus skilled performance. This study investigated how the CNS combines seen cursor positions and felt hand positions under a visuo-motor rotation paradigm. Young and older adult participants performed aiming movements on a digitizer while looking at rotated visual feedback on a monitor.

Two-phase strategy of neural control for planar reaching movements: II--relation to spatiotemporal characteristics of movement trajectory.

In the companion paper utilizing a quantitative model of optimal motor coordination (Part I, Rand and Shimansky, in Exp Brain Res 225:55-73, 2013), we examined coordination between X and Y movement directions (XYC) during reaching movements performed under three prescribed speeds, two movement amplitudes, and two target sizes. The obtained results indicated that the central nervous system (CNS) utilizes a two-phase strategy, where the initial and the final phases correspond to lower and higher precision of information processing, respectively, for controlling goal-directed reach-type movements to optimize the total cost of task performance including the cost of neural computations. The present study investigates how two different well-known concepts used for describing movement performance relate to the concepts of optimal XYC and two-phase control strategy.

Spatial realignment in sensorimotor adaptation: taking the efficiency into account.

The present study reviewed the modular approach in adaptive motor control by taking cognitive efficiency into account. Three experiments were conducted to compare different visuomotor learning mechanisms (modular adaptation, use-dependent plasticity, and spatial realignment) in response to visuomotor rotations. During exposure, the visual feedback of flicking movements in a single-target scenario was rotated either 30° clockwise (CW) or counterclockwise (CCW) at the left and right starting locations, respectively.

Vision and proprioception in action monitoring by young and older adults.

Discrimination of proprioceptive and visual spatial information is a prerequisite for the learning of visuo-motor transformations. This study investigated the individual's capability to discriminate the directions of seen cursor motions and felt hand movements under a visuo-motor rotation paradigm and its age-related variation. Young and older participants performed 3-stroke arm movements on a digitizing tablet without seeing their arm.

Two-phase strategy of controlling motor coordination determined by task performance optimality.

A quantitative model of optimal coordination between hand transport and grip aperture has been derived in our previous studies of reach-to-grasp movements without utilizing explicit knowledge of the optimality criterion or motor plant dynamics. The model's utility for experimental data analysis has been demonstrated. Here we show how to generalize this model for a broad class of reaching-type, goal-directed movements.

Two-phase strategy of neural control for planar reaching movements: I. XY coordination variability and its relation to end-point variability.

A quantitative model of optimal transport-aperture coordination (TAC) during reach-to-grasp movements has been developed in our previous studies. The utilization of that model for data analysis allowed, for the first time, to examine the phase dependence of the precision demand specified by the CNS for neurocomputational information processing during an ongoing movement. It was shown that the CNS utilizes a two-phase strategy for movement control.

Effect of aging on coordinated eye and hand movements with two-segment sequence.

This study examined how aging compromises coordinative eye-hand movements with multiple segments. Older adults and young controls performed two-segment movements with the eyes only or with the eyes and hand together. The results showed minimal age-related changes on the initiation and execution of primary saccade during the first segment.

Control of aperture closure initiation during trunk-assisted reach-to-grasp movements.

The present study investigated how the involvement and direction of trunk movement during reach-to-grasp movements affect the coordination between the transport and grasping components. Seated young adults made prehensile movements in which the involvement of the trunk was varied; the trunk was not involved, moved forward (flexion), or moved backward (extension) in the sagittal plane during the reach to the object. Each of the trunk movements was combined with an extension or flexion motion of the arm during the reach.

Adaptation of gaze anchoring through practice in young and older adults.

During visually guided manual movements, gaze is usually fixated to a target until a pointing movement is completed to that target, showing gaze anchoring. We previously examined gaze anchoring during a two-segment eye-hand task under a low accuracy constraint. Eye movements were made to predetermined first and second targets, while hand movements were varied across two conditions: (1) stop at the first target and discontinue (HS1) and (2) stop at both the first and the second targets (HS1S2).