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Biomedical subjects

J Whitall

Publications and source records attributed to J Whitall.

12 recordsLinked to original sources
PubMed2006

Perception-action coupling in children with and without DCD: Frequency locking between task-relevant auditory signals and motor responses in a dual-motor task.

BACKGROUND: The current research examines the relationship between perceptual and motor processes, known as perception-action or sensorimotor coupling, and the potential differences in perception-action coupling among children with and without Developmental Coordination Disorder (DCD) and adults in a gross-motor co-ordination task (clapping while marching) when a task-relevant driving sensory signal is present. METHODS: Ten children with DCD (7.32 + 0.23 years), eight typically developing (TD) children who were age-, gender- and racially/ethnically matched (6.91 + 0.24 years) and 10 college-aged adults were participants in this study. Participants clapped and marched to an auditory beat at four different frequencies: 0.8, 1.2,1.6 and 2.0 Hz. The relative timing measures of mean relative phase (MRP) and variability of relative phase (VRP) were calculated and compared using 3 (group) x 4 (frequency) x 2 (limb) anovas. Qualitatively, participants were assessed for the presence of absolute coupling (100% + 15% MRP). RESULTS: Statistically significant differences in MRP occurred for coupling, frequency and group, and post hoc analysis indicated that the adult group differed from both the DCD and TD groups, who did not differ from each other. In VRP, there were significant main effects for coupling and group, and a significant interaction between group and frequency, with post hoc analysis indicating the DCD group to be different from the TD and adult groups. Qualitatively, both the adult and TD groups increased in the number of participants who adopt absolute coupling as frequency increases. In contrast, the DCD participants adopt this absolute coupling far less frequently overall; in fact, the number of participants adopting this pattern decreases as frequency increases. CONCLUSIONS: These results indicate that children with DCD have difficulties with both the co-ordination and the control of their perception-action coupling for this particular task.

Adolescent↗
PubMed2001

Individual differences and similarities in the stability, timing consistency, and natural frequency of rhythmic coordinated actions.

Under preferred speed conditions, 15 adults undertook bimanual in-phase and antiphase tapping, clapping, galloping, galloping while clapping, and crawling on their hands and feet. We measured stability of interlimb coordination (standard deviation of mean interlimb relative phasing), single limb timing consistency (coefficient of variation of mean single limb cycle durations), and natural limb frequency. Pearson product-moment correlations among tasks established that only the natural limb frequencies were significantly correlated (specifically among gross motor actions in which larger contributions of inertial loads contribute to natural frequencies). Intraclass correlations were high for tasks, meaning that within each task, all participants performed similarly. Thus, only frequency has a tendency to show a common time-based process within a participant, but common time-based processes exist between participants.

Adult↗
PubMed2000

Bimanual finger tapping: effects of frequency and auditory information on timing consistency and coordination.

The authors' goal in this study was to probe the basis for an earlier, unexpected finding that preferred-frequency finger tapping tends to have higher frequencies and to be less stable for in-phase than for antiphase tasks. In follow-up experiments, 3 protocols were employed: a preferred-frequency replication in both coordination modes, a metronome-driven matching of the preferred frequencies to each of the coordination modes, and a frequency scaling of both modes. The original findings were affirmed for preferred frequency. Tapping to a metronome had a differential effect on in-phase and antiphase: A more stable coupling across frequencies was exhibited during in-phase. Under frequency scaling, the antiphase pattern decomposed at lower frequencies than did in-phase, but no phase transitions were observed. The loss of stable coordination in both modes was attended by sudden increases in frequency differences between fingers and by phase wandering. The emergence of those effects is discussed in light of asymmetric modifications to the Haken-Kelso-Bunz model (H. Haken, J. A. S. Kelso, & H. Bunz, 1985) and the task constraints of tapping.

Adult↗
PubMed2000

Accuracy of dynamic isometric force production: the influence of age and bimanual activation patters.

The purpose of this study was to investigate how children and adults control bimanual activities with the influence of kinematic variables minimized. Force and timing measures were analyzed in self-paced, isometric bimanual pinch tasks performed by 6-, 8-, 10-, 12-year-old, and adult subjects. Subjects (n = 84) performed four tasks (inphase symmetrical, antiphase reciprocal, inphase asymmetrical force-right high, inphase asymmetrical force-left high) cycling between low levels (10--30%) of maximal volitional force during three 15-s trials. Bimanual tasks requiring similar activation between the hands were performed more accurately, more quickly, and with less force and timing variability than tasks requiring different actions and/or levels of force to be produced simultaneously. Evidence of force entrainment between the hands was exhibited when force direction (increasing vs. decreasing) was similar between hands but greater relative force was required of the left hand. Lower accuracy and greater variability resulted when controlled decrement of force was required to reach the lower force targets as opposed to the upper force targets which required subjects to increase force. Subjects in the two youngest age groups exhibited lower force accuracy and greater force and timing variability relative to older children and adults. Twelve-year-old subjects approximated adults' performance in all variables.

Adolescent↗
PubMed2000

Repetitive bilateral arm training with rhythmic auditory cueing improves motor function in chronic hemiparetic stroke.

BACKGROUND AND PURPOSE: Chronic upper extremity hemiparesis is a leading cause of functional disability after stroke. We investigated the hypothesis that bilateral arm training with rhythmic auditory cueing (BATRAC) will improve motor function in the hemiparetic arm of stroke patients. METHODS: In this single group pilot study we determined the effects of 6 weeks of BATRAC on 14 patients with chronic hemiparetic stroke (median time after stroke, 30 months) immediately after training and at 2 months after training. Four 5-minute periods per session (3 times per week) of BATRAC were performed with the use of a custom-designed arm training machine. RESULTS: The patients showed significant and potentially durable increases in the following: Fugl-Meyer Upper Extremity Motor Performance Test of impairment (P<0.0004), Wolf Motor Function Test (performance time measure, P<0.02), and University of Maryland Arm Questionnaire for Stroke measuring daily use of the hemiparetic arm (P<0.002). Isometric strength improved in elbow flexion (P<0.05) and wrist flexion (P<0.02) for the paretic arm and in elbow flexion (P<0.02) and wrist extension (P<0.02) for the nonparetic arm. Active range of motion improved for paretic-side shoulder extension (P<0.01), wrist flexion (P<0.004), and thumb opposition (P<0.002), and passive range of motion improved for paretic wrist flexion (P<0.03). CONCLUSIONS: -Six weeks of BATRAC improves functional motor performance of the paretic upper extremity as well as a few changes in isometric strength and range of motion. These benefits are largely sustained at 8 weeks after training cessation.

Acoustic Stimulation↗
PubMed1999

Motor overflow and children's tracking performance: is there a link?

The aim of this study was to investigate the interaction of skill performance, motor overflow, and hand linkage in the form of mirror movements in a visual-manual tracking paradigm across practice trials. We hypothesized that both the amount of motor overflow and the degree of hand linkage would be linked in an inverse way to the quality of task performance. Furthermore, we expected a short-term decrease in both of these factors as children practiced and improved their task performance. Sixteen right-handed, 6-year-old children tracked a visual target with their right hand by pinching two parallel steel bars instrumented with strain gauges. The left hand was also positioned by similar instrumented steel bars to measure overflow/mirroring. At both the beginning and end of practice trials, a cluster analysis was used to determine relationships among performance, overflow, and hand linkage variables. In general, the results support the main hypothesis that the amount of motor overflow and the degree of hand linkage are linked to the quality of task performance, but the relationships between these variables across short-term learning are nonlinear.

Attention↗
PubMed1996

On the interaction of concurrent verbal and manual tasks: which initial task conditions produce interference?

The presence of interference (and whether it is generalized or lateralized) is highly dependent on the initial conditions of the experiment. Changes in task, instructions, and subject characteristics produce different interference outcomes. Clearly the present results are not predictable from the cerebral functional distance theory and support the idea that the theory has limited explanatory power depending on the specific tasks and conditions involved. Alternatively, the idea of entrainment among tasks can account for some of the results, particularly for the preferred-speed conditions. In other words, the interference may be interpreted in terms of a task integration of two motor responses into a common rate rather than in terms of structural interference effects (cf., Murphy & Peters, 1994). From this viewpoint, it would appear that much more could be gained by systematically changing the test conditions (task constraints) to determine the different sources of interference and/or by testing specific populations (e.g., Bathurst & Kee, 1994). In the meantime, if an experimenter is specifically looking for lateralized interference in a dual-task paradigm it might be better either not to choose unimanual tapping or to avoid the motor task of finger tapping altogether so that attentional capacity is not confounded by the effects of nonattentional, mutually interacting outcomes. In general, the results of this study reflect the sentiment of Abernathy (1988), who suggests that the application of the dual-task paradigm to problems in motor skills research requires careful consideration of the available constraints operating in specific conditions.

Adult↗
PubMed1995

From walking to running: applying a dynamical systems approach to the development of locomotor skills.

Developmental transitions of complex systems may be studied by selecting (collective) variables that constrain the degrees of freedom for each developmental state. In a dynamical systems approach, the transitions from state to state are engendered through the scaling of contributing subsystems (control parameters). In this study, the locomotor skills of walking and running were compared in newly running infants by observing several likely collective variables including relative stance, estimated pathway of center of mass, and segmental/joint action. 4 children were filmed longitudinally at 5.5, 7.5, and 9.5 months of independent walking and then at 3 years of age. 3 trials per gait were selected for single stride analysis and compared with data from 4 adults. In general, the proposed collective variables showed transitional forms over the first few months of running, indicating a relatively continuous change between the 2 gait forms. Coordination of the knee joint was very similar between gaits and across age, but the ankle joint was less consistent for both gaits in the infants. Relative stance and stride length data indicated that the children could not generate vertical and horizontal displacement. These findings echo those found in newly walking infants and suggest that similar rate-limiting parameters are present for both gaits.

Adult↗
PubMed1992

Coordination of symmetrical and asymmetrical human gait.

Most human gait forms assume symmetrical, alternating patterns of interlimb coordination (e.g., crawling, walking, running). Human galloping is a notable exception. In contrast to extensive information on galloping in animals, little is known about this gait in humans. Therefore, kinematic and topographical analyses of running and galloping were undertaken to investigate the manner in which the lower limbs are uncoupled to produce this asymmetrical gait. Seven adult females were filmed while running and galloping at their preferred speed. Analysis of the gaits revealed differences in the following: (a) preferred speed, (b) coupling between upper- and lower-limb girdles, and (c) point of foot fall (end-point trajectories). In contrast to clear differences in interlimb coordination, intralimb coordination was remarkably similar across gaits, although when galloping was adopted, the rear leg did show more variable change than the front leg.

Journal Article↗
PubMed1989

A developmental study of the interlimb coordination in running and galloping.

Using a dynamical systems perspective on motor behavior, it was predicted that interlimb coordination of running and galloping would behave like coupled, nonlinear, limit-cycle oscillators, which show the properties of phase locking, entrainment, and structural stability. Female subjects ranging in age from 2.5 years to adult were filmed while running and galloping with and without a weight perturbation. Analysis of both temporal- and amplitude-phasing measures revealed that both gaits demonstrated oscillatory properties. Differences between gaits and across age were primarily a matter of degree. In general, children 4 years of age and below had slightly less table phasing patterns, and all age groups showed slightly less ability in the gallop, particularly with amplitude phasing.

Journal Article↗
PubMed1988

Human interlimb coordination: the first 6 months of independent walking.

The organization of interlimb coordination was studied in newly walking infants with and without support and in infants who had been walking 0.5, 1, 3, and 6 months. Analysis of the temporal and distance phase relationships between the limbs revealed that newly walking infants exhibit interlimb coordination similar to that of mature walkers. The coupling between the limbs, however, is loosely constrained, approaching adult-like consistency after 3 months of walking. Providing support for the newly walking infant afforded a more consistent, mature coordination suggesting that neuromuscular development is in advance of its ability to function in the physical world.

Child Development↗