Publications by authors named "Takahiro Horaguchi"

Background: Drinking well water contaminated with the organoarsenic compound diphenylarsinic acid (DPAA) causes central nervous system (CNS) disorders that improve within several years after last drinking such water. Subjective symptoms such as lightheadedness and dizziness appear to persist, however, suggesting CNS damage. We evaluated CNS damage due to DPAA by detecting abnormal eye movements.

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Behavioral and neurophysiological studies of numerical comparisons have shown a "distance effect," whereby smaller numerical distances between two digits are associated with longer response times and higher activity in the parietal region. In this experiment, we introduced a two-choice condition (between either the smaller/lower or the larger/higher of two digits) and examined its effect on brain activity by fMRI. We observed longer response times and greater activity with the choice of smaller numbers ("choice effect") in several brain regions including the right temporo-parietal region, (pre)cuneus, superior temporal sulcus, precentral gyrus, superior frontal gyrus, bilateral insula, and anterior cingulate cortex.

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Extensive behavioral and neurophysiological numerical comparison studies have shown that response times are longer and parietal activities are stronger when the numerical distance between two digits is smaller (the distance effect). However, only a few behavioral studies have considered the effect of the choice of larger or smaller numerals in numerical comparisons. Using near-infrared spectroscopy (NIRS), we investigated the neural basis of choosing larger/smaller numerals in number comparison tasks in which subjects were required to choose a larger or smaller digit.

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It has been proposed that positional memories encoded in different types of reference frame are used for the reaching hand movement in different stages of learning. However, the types of reference frame employed for generating behavior at each stage of learning remain unclear, particularly for saccades. To examine the types of reference frame for target positions, we analyzed the saccade of monkeys performing an oculomotor task.

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