Effects of excitation light intensity on parathyroid autofluorescence

The intraoperative identification and preservation of the parathyroid glands are vital techniques, which are largely dependent on a surgeon’s experience. Therefore, a simple and reproducible technique to identify the parathyroid glands during surgery is needed. Parathyroid tissue shows near-infrared (NIR) autofluorescence, which enables the intraoperative identification of the parathyroid gland. We herein present two cases that underwent surgery on the parathyroid glands, which were observed using the NIR fluorescence imaging system LIGHTVISION® (Shimazu, Kyoto, Japan). In a case of papillary thyroid carcinoma, the system was adopted to preserve normal parathyroid glands during left hemithyroidectomy. The left lower parathyroid gland was identified using the imaging system under white light; however, its autofluorescence was visualized more clearly with the excitation light of NIR. In a case of primary hyperparathyroidism due to MEN1, the system was adopted to identify and remove all of the parathyroid glands during total parathyroidectomy. The autofluorescence of diseased glands was weaker than that of normal glands, even with the excitation light of NIR. When the parathyroid glands were irradiated with a red laser pointer, the intensity of autofluorescence significantly increased. However, the largest gland, which was pathologically proven to contain strongly proliferating chief cells, did not show autofluorescence. These results suggest that normal or less diseased parathyroid glands, which are generally small and difficult to identify during surgery, showed relatively strong autofluorescence. A stronger excitation light increases the autofluorescence of parathyroid glands, which enhances sensitivity for detecting parathyroid glands during surgery. In conclusion, LIGHTVISION® is a useful device to identify parathyroid glands and an additional excitation light of a red laser pointer increases the detection sensitivity

Effect of Visuospatial Attention on the Sensorimotor Gating System

The integration of multiple sensory modalities allows us to adapt to the environment of the outside world. It is widely known that visual stimuli interfere with the processing of auditory information, which is involved in the ability to pay attention. Additionally, visuospatial attention has the characteristic of laterality. It is unclear whether this laterality of visuospatial attention affects the processing of auditory stimuli. The sensorimotor gating system is a neurological process, which filters out unnecessary stimuli from environmental stimuli in the brain. Prepulse inhibition (PPI) is an operational measure of the sensorimotor gating system, which a weaker prestimulus (prepulse), such as a visual stimulus, inhibits the startle reflex elicited by a subsequent robust startling stimulus (pulse) such as a tone. Therefore, we investigated whether the visual stimulus from the left or right visual space affects the sensorimotor gating system in a “rest” task (low attentional condition) and a “selective attention” task (high attentional condition). In the selective attention task, we found that the target prepulse presented in the left and bilateral visual fields suppressed the startle reflex more than that presented in the right visual field. By contrast, there was no laterality of PPI in the no-target prepulse condition, and there was no laterality of PPI in the rest task. These results suggest that the laterality of visuospatial attention affects the sensorimotor gating system depending on the attentional condition. Moreover, the process of visual information processing may differ between the left and right brain