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Abstract:
Abstract: The close relationship between the control of real
and imagined movements has been well demonstrated both
behaviourally and through functional neuroimaging. In general,
imagined performances closely resemble actual performances and make
use of overlapping neural circuitry. We asked subjects to perform
real and imagined visually guided pointing movements in the upper
and lower visual fields (upVF and loVF respectively). Movements
made in the loVF showed a strong speed accuracy trade-off such that
movement durations decreased in a linear fashion as target width
increased. In contrast, actual movements made in the upVF were more
variable and showed only a weak relationship to target width. A
similar difference was observed when subjects imagined making
movements. That is, the linear relationship between target width
and the duration of the imagined movement was much clearer in the
loVF. This difference in performance between the lower and upper
visual fields suggests that the neural circuitry subserving
processing within the loVF may be functionally specialized for the
control of visually guided behaviours such as pointing.
Furthermore, the fact that performance of imagined movements
followed a similar pattern to that observed with real movements
suggests that imagined movements depend on many of the same
cognitive and neural mechanisms involved in the control of real
movements.
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