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Attention and interlimb coordination: behavioural and neurophysiological processes


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Hiraga, CY (2005) Attention and interlimb coordination: behavioural and neurophysiological processes. PhD thesis, University of Tasmania.

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A conceptual and methodological framework has recently been developed from a
blending of a traditional dual-task methodology and a dynamical perspective on
coordination. Specifically, pattern stability has been shown to be a good predictor of
attentional demands (i.e., central cost) needed for maintaining coordination. One of the
important assumptions is that the allocation of attentional resources can modify the
coupling strength of interlimb coordination. Within this original framework that blends
two different theoretical approaches with attention as an intervening variable modifying
behavioural patterns, the present research further investigated at the behavioural and
neurophysiological levels, the central cost of dynamical coordination patterns.
Two experiments were carried out in the Phase 1 of the present research. The first
examined whether previous findings obtained with bimanual coordination patterns could
be extended to coordination patterns involving non-homologous limb combinations.
Consistent with previous results, coordination stability and probe RT (i.e., a measure of
attentional load) were found to co-vary. Furthermore, it was shown that temporal aspects
of the coordination task were selectively modulated through attentional prioritisation
without affecting the spatial aspects of the task (i.e., movement trajectories).
Following evidence from Experiment 1 of dissociation between the temporal and
spatial dimensions of interlimb coordination, the second experiment explored whether
attentional focus could selectively modulate the spatial aspects of the interlimb
coordination task without affecting the temporal coupling between the limbs. Experiment
2 showed that when the spatial aspects of the interlimb coordination task were prioritised not only the movement trajectories but also the temporal variability of the interlimb
coordination task were modulated. Interestingly, attentional focus to the spatial
dimension of interlimb coordination abolished the inherent performance asymmetries
usually observed between the limbs (i.e., spontaneous performance differences between
the left-hand and the right-hand and an ann and leg).
Phase 2 of this research explored the neural correlates of dual-task performance
involving an interlimb coordination and probe RT task. Single-pulse transcranial
magnetic stimulation (TMS) was employed in a series of three experiments to specifically
assess the excitability of corticospinal pathways during single- and dual-task
performance. The first experiment examined the time course of corticospinal excitability
of the tibialis anterior (TA) during the RT interval to a secondary task probe stimulus
while simultaneously maintaining bimanual in-phase and anti-phase coordination modes.
Although corticospinal excitability of the TA did not differ between the in-phase and
anti-phase coordination modes, a large increase in corticospinal excitability was observed
between single-task and dual-task performance.
The second experiment examined whether the elevated corticospinal excitability
during dual-task performance was a 'motor effect' reflecting increased cortical
excitability associated :.vith the performance of the continuous bimanual coordination task
or it whether reflected the concurrent performance of two tasks (i.e., a dual-task effect).
The results showed that the elevation of corticospinal excitability was due, in part, to the
production of bimanual movements. However, a further increase in corticospinal
excitability also occurred in the dual-task condition. Thus, the increased corticospinalexcitability appeared to reflect a neural process related to the concurrent performance of
two tasks.
A final experiment tested whether the increased corticospinal excitability was a
general signature of dual-task performance or specific to interactions within the motor
cortex. Dual-task conditions involving either a primary motor task or a primary cognitive
task (i.e., tone counting) combined with probe RT were compared. Results showed that
increased corticospinal excitability was not a general effect of dual-task performance, but
specific to dual-task situations involving motor tasks.
Overall, the findings of the experiments conducted in this research exploring
attention and coordination dynamics provided further support to the view that attentional
allocation impacts on the coupling strength between the limbs and affects both the
temporal and spatial dimensions of interlimb coordination. Furthermore, at the neural
level, dual-task effects showed different neural manifestations for structural interference
and capacity interference.

Item Type: Thesis (PhD)
Additional Information:

Copyright 2005 the author

Date Deposited: 18 Mar 2010 03:52
Last Modified: 11 Mar 2016 05:54
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