Variability In The Location And Size Of V2 In Humans

PET and MRI imaging have been used to investigate the location and variability of areas V1, V2, VP, V3A, and V4 defined through functional topographic mapping. During PET imaging, 11 subjects viewed dynamic random dot patterns that were arranged as "bowties" along either the horizontal or vertical meridian. Regional blood flow (rCBF) was calculated as deviation from the rest condition for stimulation of either the vertical or horizontal meridian sectors. The resultant PET images were then normalized into the Talairach and Tournoux stereotaxic space. The MRI images from each subject were similarly normalized to Talairach space, and the PET data were coregistered with the MRI anatomical images. The center of area V2 was calculated as the midpoint between the representations of the horizontal and vertical meridia in both dorsal and ventral cortex. The borders of area V2 were consistently observed in the right hemisphere of all 11 subjects and in the left hemisphere in 10 of 11 subjects. Table III summarizes the mean location and standard deviation of the center of gravity of area V2 in the three Talairach coordinates. Overall, the center of gravity of V2 has a mean standard deviation of approximately 5 mm, but it is more consistently localized in the x plane (SD=4.075 mm) and least consistently localized in the z plane (SD=5.975 mm).

Conquering Fear In The 21th Century

Conquering Fear In The 21th Century

The Ultimate Guide To Overcoming Fear And Getting Breakthroughs. Fear is without doubt among the strongest and most influential emotional responses we have, and it may act as both a protective and destructive force depending upon the situation.

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