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Abstract:
Abstract: The relationship between neural speed and
intelligence has been well documented. To further explore this
relationship we used whole head MEG to evaluate intra- and
inter-hemispheric processing during a task in which a circular high
spatial frequency grid was presented either to the right- or
left-visual fields. MEG and reaction time data was collected for
three motor conditions: (1) Respond always with the right hand, (2)
respond always with the left hand, or (3) respond with the hand
contra-lateral to the stimulus. Over visual areas of the brain
there was clear lateralization of initial visual response. Activity
over sensory-motor areas was constrained to motor cortex
contra-lateral to the responding hand, irrespective of field of
stimulus presentation. When comparing inter-hemispheric trials
where the motor response was not known apriori (decision condition)
to those where it was (non-decision), a significant delay was
introduced by response uncertainty. This delay was associated with
activation in the superior parietal region which appeared to be
"inserted" in the processing chain immediately prior to
sensory-motor activation in the hemisphere contra-lateral to the
response. Duration of this waveform was significantly correlated
with intelligence, measured by RAPM score (r=-.89, p=.02,
n=5).
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