Previous electrophysiological, neuroimaging and lesion studies have suggested that the anterior part of the monkey inferior temporal (IT) cortex, or area TE, plays an important role in colour processing. However, little is known about how colour information is distributed in these cortical regions. Here, we explored the distribution of colour‐selective activity in alert macaque monkeys using functional magnetic resonance imaging (fMRI) with two types of stimuli: a multicoloured (‘Mondrian’) pattern and an isoluminant colour grating. These two types of stimuli are both commonly used in human fMRI studies, but Mondrian stimuli, which contain a richer variety of hues and hence might be more suitable for activating higher‐order areas than grating stimuli, have not been used to examine colour‐selectivity in higher‐order areas in earlier monkey studies. With the Mondrian stimuli, we observed that areas along the ventral pathway, V1, V2/V3, V4 and the IT cortex, responded more strongly to colour stimuli than to luminance stimuli. In the IT cortex, we found that colour‐selective activities are not distributed uniformly, but are localized in discrete regions, each extending several millimetres in the anterior or posterior part of the IT cortex. The colour‐selective activation in the anterior IT was observed only with the Mondrian stimuli, whereas the colour‐selective activation in the posterior IT was observed with both the Mondrian and grating stimuli, with little overlap. These findings suggest that there are multiple subregions with differing stimulus selectivities distributed in the IT cortex, and that colour information is processed in these discrete subregions.
The purpose of this study was to investigate the accuracy of distance measurements of implant length based on periapical radiographs compared with that of other modalities. We carried out an experimental trial to compare precision in distance measurement. Dental implant fixtures were buried in the canine and first molar regions. These were then subjected to periapical (PE) radiography, panoramic (PA) radiography, conventional (CV) and medical computed (CT) tomography. The length of the implant fixture on each film was measured by nine observers and degree of precision was statistically analyzed. The precision of both PE radiographs and CT tomograms was closest at the highest level. Standardized PE radiography, in particular, was superior to CT tomography in the first molar region. This suggests that standardized PE radiographs should be utilized as a reliable modality for longitudinal and linear distance measurement, depending on implant length at local implantation site.
The skin of toxic puffers (Fugu niphobles, F. vermicularis vermicularis and F. pardalis) was found to release 5-80MU of tetrodotoxin (TTX) per specimen when lightly stimulated by handling. The puffer did not release any more toxin when the handling stimuli were repeated 3-5 times at a 30 min-interval. Some of them, however, recovered to release TTX on handling stimulus when kept intact for two weeks. The cultured puffer (F. rubripes rubripes) specimens which were arti ficially toxified by feeding with toxic puffer livers, released TTX up to 540 MU on a single handling stimulus.From these and other results, it was strongly suggested that TTX acts as a biological defense agent in puffers.
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