1 |
EXTRA-PERSONAL GAZE INFLUENCES ON THE EYE TO HAND SPATIAL INTERFERENCE EFFECTMarshall, Rachèle 11 1900 (has links)
An examination into the influence of observed gaze cues on motor output. / Richardson and colleagues (2013) demonstrated oculo-manual spatial interference by finding that the finger trajectory in a vertical tapping task deviated toward the direction of a concurrent saccade. It was proposed that the entrainment of the hand to the eyes was in part a function of generalized motor planning. Human action observation research has shown that cortical motor planning is also active during action observation (e.g. Buccino et al. 2001; Decety et al. 1997), which can lead to other forms of spatial interference (Kilner et al 2003). We hypothesized that because motor planning subserves both observation and execution of action, simply observing the horizontal saccades of another person would cause sufficient recruitment of oculomotor planning structures, that would result in finger tap trajectory deviations toward the direction of the observed saccade (but would not do so in a non-biological observation control condition).19 participants performed 24 trials of vertical finger taps under three different visual conditions. They were required to: a) saccade horizontally between targets; b) fixate on a biological stimulus (i.e. a video of horizontally saccading human eyes); or c) fixate on a non-biological control stimulus (horizontally moving black dots) while tapping their finger to an auditory metronome beat presented at a 750ms intervals. Results from the saccading condition replicate Richardson et al’s (2013) entrainment effect. That is, finger taps deviated to the left when participants saccaded left, and to the right when executed with a rightward saccade. Contrary to expectations however, there was no entrainment induced by observing either the biological stimulus or the control stimulus. This suggests that competing motor plans (eyes and hands) are necessary to induce interference. Further, simply observing eye movements do not recruit the same oculomotor planning networks as action execution. / Thesis / Master of Science in Kinesiology
|
2 |
RAPID ADAPTATION OF REACTIVE FORCE CONTROL WHEN LIFTING OBJECTSMarkovik, SIMONA 04 February 2013 (has links)
The control of object manipulation tasks involves the close interplay of predictive and reactive control mechanisms. For example, when lifting an object, people typically predict the weight based on object size and material as well as sensorimotor memory obtained from previous lifts of the object. When lifting objects with a precision grip, people increase vertical load force to a target level that slightly exceeds the predicted weight. When the object is heavier than expected, the mismatch between expected and actual tactile signals associated with lift-off triggers a corrective action within ~100 ms, that involves probing increases in load force that continue until the object is lifted. Here we investigated whether this correction action can be adaptively influenced by experience. Participants repeatedly lifted an object that was instrumented with force sensors to measure the forces applied by the fingertips, with weight that could be varied without the knowledge of the participant. In 80% of trials, the weight was set to 2 N and, in different blocks of 110 trials, the remaining 20 % of trials (2 trials randomly selected from each successive 10 trials) was set to either 4 or 6 N. We found that the rate of change of the reflexively triggered increase in load force that occurred in the 4 or 6 N trials, scaled with the additional weight. That is, following the initial increase in load force to ~2 N, the subsequent increase in load force was more rapid for the 6 N object than the 4 N object. In contrast, the onset time of the reactive increase in load force was independent of the additional weight. Finally, this adaptation of reactive load force control took place quickly and was evident after only a few lifts of the heavier weight. These results indicate that the reactive increases in load force that occur when a lifted object is heavier than expected can be adapted and tuned, to refine behavior. This further suggests that multiple predictions can be generated about object weight when lifting. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2013-02-02 13:34:20.533
|
3 |
STABILITY MODULATION IN FINGER-FORCE PRODUCTION TASKSPaige A Thompson (10716468) 06 May 2021 (has links)
<p>Stability is the ability of a system
to reject noise and maintain or return to the desired movement pattern and is
an important feature of a motor system. In contrast, maneuverability is the
ability of a system to transition between different motor states. A system that
prioritizes stability inhibits its ability to transition between different
motor states in a dexterous fashion. Since stability and maneuverability are opposing
characteristics of a system, stability could be traded off to increase
maneuverability. This
study focuses on isometric finger force production, and its goals were to
identify whether (1) the amount of information available about an upcoming
motor transition influences the reduction in stability of total isometric force
produced by the fingers, (2) stability reduction was correlated with greater
maneuverability, i.e., less time for initiating a change in the total force,
(3) the amount of stability reduction is correlated across tasks with different
amount of information regarding the upcoming force changes, and (4) the times
required to change force correlated across tasks with different informational
content. </p>
<p>Twenty-nine young
adults (17 women; age, 23.3 ± 4.3 years) participated in this study and
completed three different finger force tasks. For each task, the participants
modulated the total pressing force produced by the four fingers of their right
hand to track a target presented on a computer screen. In each task,
participants began by producing a consistent (10% of their maximum voluntary
contraction, MVC) background force with their fingers. In the Steady task, the
target remained stationary and participants knew the target would not move. In
the Reaction Time (RT) task, the target moved randomly in the vertical
direction and participants knew that this could happen at any point in time. In
the Self-paced task, participants started producing a background force and then
produced a quick increase in total force using a predefined target that was
displayed at the beginning of the trial, and visible throughout the trial. </p>
<p>The uncontrolled
manifold analysis was used to assess the stability of the total force during
each task. This assessment was performed when the participants produced the same
force (10% MVC), but expected different upcoming force changes, and had
different amount of information about these upcoming force changes. This
analysis yielded a stability index, and measures of the variance structure in
the finger forces, computed across multiple repetitions. The reaction time and
the movement time in the RT and the Self-paced tasks, respectively, was
computed to quantify maneuverability. </p>
<p>In contrast to
previous findings and our expectations, the stability index was not statistically
different for the Steady, RT, and Self-paced tasks, meaning that stability of
the total force was not reduced in response to the mere expectation of an
upcoming change in total force. However, the stability index reduced immediately
before individuals changed their total force in the Self-paced tasks, which supports
findings from previous studies. The stability modulation between the Steady and
RT tasks did not correlate with the RT, and the stability modulation between
the Steady and Self-paced tasks did not correlate with the movement time. Therefore,
this study did not reveal a stability-maneuverability trade-off in isometric
finger force production tasks. The movement time for the RT and Self-paced
tasks were also not correlated. However, the novel finding of this study was
that participants changed stability similarly for the RT and Self-paced tasks.</p>
<p>Finally, the
variance components obtained from the uncontrolled manifold analysis were
higher in the RT task compared to the Steady task, consistent with previous
reports. In fact, the increase in the performance error (greater variability in
total force) while expecting to change total force in uncertain conditions (RT
tasks) is the most striking and consistent result across multiple similar studies.
This result indicates that despite the inconsistent results regarding the stability
index, the performance of the current task (producing a constant total force)
is hampered by the uncertainty and the expectation of upcoming changes in total
force.</p>
<p>It is likely that the
stability-maneuverability trade-off is not essential for young, healthy adults
in manual force production tasks. Investigations that include participants
across the lifespan will shed light on this relation and help identify whether
it plays a salient role in understanding loss of manual dexterity with healthy
aging. </p>
|
4 |
Entirely digital permanent magnet synchronous machine controller by a single digital signal processor chipGarate, Inaki January 1990 (has links)
No description available.
|
5 |
Peripheral and central influences on the electromographic responses of muscle to transcranial magnetic stimulation in manMaskill, David William January 1995 (has links)
No description available.
|
6 |
Excitability of somatic afferent pathways to the motor cortex during locomotion in the catMontgomery, Alistair Scott January 1993 (has links)
No description available.
|
7 |
The movement mental imagery ability and acquisition rate relationshipLovell, G. P. January 1998 (has links)
No description available.
|
8 |
A self-commutating inverter-induction motor drive controlled by a microprocessorMbuthia, Mwangi J. January 1984 (has links)
No description available.
|
9 |
Functions of basal ganglia in man and monkeyCanavan, A. G. M. January 1986 (has links)
No description available.
|
10 |
Computers, Brains, and the Control of MovementHollerbach, John M. 01 June 1982 (has links)
Many of the problems associated with the planning and execution of human arm trajectories are illuminated by planning and control strategies which have been developed for robotic manipulators. This comparison may provide explanations for the predominance of straight line trajectories in human reaching and pointing movements, the role of feedback during arm movement, as well as plausible compensatory mechanisms for arm dynamics.
|
Page generated in 0.0645 seconds