Biomedical subjects

Rachael D Seidler

Publications and source records attributed to Rachael D Seidler.

6 recordsLinked to original sources

PubMed2007

Aging affects motor learning but not savings at transfer of learning.

Two important components of skill learning are the learning process itself (motor acquisition) and the ability to transfer what has been learned to new task variants (motor transfer). Many studies have documented age-related declines in the ability to learn new manual motor skills. In this study, I tested whether the degree of savings at transfer of learning is similarly affected by advancing age. Young and older adults made aiming movements with a joystick to hit targets presented on a computer screen, with real-time feedback display of their movement. They adapted to three different rotations of the feedback display in a sequential fashion, with return to the normal feedback display between each. Adaptation performance was better when it was preceded by other adaptive experiences, regardless of age.

Adult↗

PubMed2006

Differential effects of age on sequence learning and sensorimotor adaptation.

Although many studies have documented declines in the ability of the elderly to learn new manual motor skills, studies have not directly compared the capacity of older adults to learn sequences versus adapt to sensorimotor perturbations within the context of the same task paradigm, despite differences in the underlying neural mechanisms and strategic processes supporting the two types of learning. The purpose of the current study was to exploit these task differences in an effort to determine whether aging results in a generalized or more specific skill learning deficit. Groups of young and older adult subjects learned to make a sequence of actions, adapted to one of two visuomotor rotations, or adapted to an altered gain of display, all while performing the same basic manual joystick aiming task. While the older adults exhibited normal sequence learning in comparison to the young adults, they exhibited impairments in all three of the adaptation tasks. These deficits in adaptation for the older adults were associated with hypometric movements and reduced velocity modulation in comparison to that seen in the younger adults. These data suggest that older adults may have greater difficulty with learning cerebellar-mediated motor skills.

Acclimatization↗

PubMed2003

The size of corpus callosum correlates with functional activation of medial motor cortical areas in bimanual and unimanual movements.

Effects of the size of corpus callosum measured from in vivo magnetic resonance imaging (MRI) recordings on cortical activations evaluated using functional MRI (fMRI) were analyzed during motor tasks. Twelve right-handed men performed unilateral finger movements and bilateral movements either with or without a temporal delay between left and right fingers. The size of the rostral part of corpus callosum and the anterior and posterior callosal truncus explained 11.9 and 15.2% of activation in the mesial frontal cortex in unimanual left and right finger movements, respectively. In bimanual simultaneous movements, 34.2% of the activated voxels in the mesial frontal cortex were related to the size of corpus callosum. In bimanual movements in which left finger movement preceded the onset of the right finger movement, the callosal size accounted for 88.7% of activation in the mesial frontal cortex. In contrast, when the right finger movement preceded the left, callosal size accounted for only 31.3% of the mesial frontal cortex activation. The correlations between callosal parameters and activation over the lateral cortex were sparse and occurred only in bimanual movements. The results suggest that corpus callosum modulates the activity of the supplementary motor and cingulate cortical areas depending on temporal complexity of bimanual movements.

Adult↗

PubMed2002

Age-related kinematic differences as influenced by task difficulty, target size, and movement amplitude.

Fifteen older adults (M = 68 years old) and 15 young adults (M = 23 years old) participated in a speed-accuracy task in which aiming movements were performed on a digitizing tablet to assess movement slowing and variability in older adults. Target-size and movement amplitude influences were analyzed separately to determine if they affected the performance of the young and older adults differently. When target size was increased, older adults did not increase the relative distance traveled in the primary submovement. When movement amplitude was increased, older adults did not scale movement velocities to the same magnitude as young adults did. Both the inability to scale velocity and the inability to increase the relative distance traveled in the primary submovement contribute to slower, more variable movements observed in older adults depending on task parameters. Thus, these data reveal that manipulation of target size and movement amplitude yield two distinct factors that contribute to slowness of movement in older adults.

Adult↗

PubMed2002

Changes in multi-joint performance with age.

The purpose of this study was to determine whether elderly adults exhibit deficits in the performance of multi-joint movements. Two groups of subjects (mean ages, 68.9 and 30.1 years, respectively) participated in this experiment. Subjects performed planar arm pointing movements to various targets. One target could be achieved via elbow extension only, while the remaining 3 required both elbow extension and horizontal shoulder flexion, thus requiring coordination at the 2 joints. In contrast to the young adults, the elderly adults produced movements that became less smooth and less accurate with increasing shoulder joint contribution. The results imply a selective coordination deficit for the elderly adults. In addition, the elderly adults coactivated opposing muscles more than the young adults for the single-joint movement. However, the elderly adults reduced coactivation at both joints for the 2-joint actions, while the young adults did not. These data suggest a relationship between high coactivation levels and good performance for elderly adults. It may be more difficult for the elderly to implement high coactivation levels for multi-joint movements because of the increased energy costs and complexity of planning required in comparison to the single joint actions. Thus, to achieve motor performance, elderly persons appear to use coactivation in a manner that is fundamentally different than young adults.

Adult↗

PubMedDate not supplied

Multiple motor learning experiences enhance motor adaptability.

Traditional motor learning theory emphasizes that skill learning is specific to the context and task performed. Recent data suggest, however, that subjects exposed to a variety of motor learning paradigms may be able to acquire general, transferable knowledge about skill learning processes. I tested this idea by having subjects learn five different motor tasks, three that were similar to each other and two that were not related. A group of experimental subjects first performed a joystick-aiming task requiring adaptation to three different visuomotor rotations, with a return to the null conditions between each exposure. They then performed the same joystick-aiming task but had to adapt to a change in display gain instead of rotation. Lastly, the subjects used the joystick-aiming task to learn a repeating sequence of movements. Two groups of control subjects performed the same number of trials, but learned only the gain change or the movement sequence. Experimental subjects showed generalization of learning across the three visuomotor rotations. Experimental subjects also exhibited transfer of learning ability to the gain change and the movement sequence, resulting in faster learning than that seen in the control subjects. However, transient perturbations affected the movements of the experimental subjects to a greater extent than those of the control subjects. These data demonstrate that humans can acquire a general enhancement in motor skill learning capacity through experience, but it comes with a cost. Although movement becomes more adaptable following multiple learning experiences, it also becomes less stable to external perturbation.

Adaptation, Physiological↗