[Clinical Study of HoLEP for the Patients with Benign Prostatic Hyperplasia who are on Oral Antithrombotics].

Recently, holmium laserenucleation of the prostate (HoLEP) was associated with less bleeding compared with transurethral resection of prostate. Since 2012, we have performed HoLEP for benign prostatic hyperplasia (BPH) under continuous oral antithrombotics (OA). Between October 2004 and March 2015, 54 patients with BPH underwent HoLEP while on OA at our hospital. Eight patients underwent HoLEP without OA cessation and 46 patients with temporary OA cessation. No significant between-group difference was observed in age, prostate volume, transitional zone prostate volume, operation time, resection weight, resection weight per minute, urethral catheter duration, Hb decrease on day 1 post- HoLEP, hospital stay after HoLEP, bleeding intraoperative rate, bleeding rate after HoLEP and transfusion rate. None presented embolic complications. HoLEP was safe without OA cessation. However, highvolume BPH patients without OA cessation required intraoperative transfusion. Thus, high-volume BPH patients may benefit from OA cessation.

Memory trace dependence on number of stimuli in magnetic mismatch negativity.

Mismatch negativity (MMN) reflects a comparison process between a deviant stimulus and the memory trace of standard stimuli. Although this memory mechanism has been investigated by many research studies, the development of memory representation still remains unclear. In this study, we focused on the development of sound trace underlying the MMN response. We measured the magnetic counterpart of MMN (MMNm) in detail, when the neural trace of the standard sound was developed in accordance with the number of standard stimuli. When the number of standard stimuli increased, MMNm latency significantly shortened and the MMNm amplitude showed no significant change. Thus, the developmental effects on memory trace may differ between MMNm amplitude and MMNm latency.

The development of memory trace depending on the number of the standard stimuli.

The mismatch negativity (MMN) component of the event-related potentials reflects the automatic detection mechanism of sound change. MMN is elicited by a neuronal mismatch process between deviant (infrequent) auditory input and the sensory memory trace of the standard (frequent) stimuli. Although many previous studies have investigated MMN to reveal the sensory memory mechanism, the development of memory representation still remains unclear, in particular, the topographical aspect of the trace-development in sensory memory has not been clarified. We measured the frontal and the temporal MMN components, respectively, when the sound trace was developed as the number of standard stimuli was changed to 1, 3, 5 or 7. In this experiment, the inter-train interval was 15 sec. The stimulus train with the different frequency of 800 Hz, 900 Hz, or 1000 Hz was repeatedly presented. Thus, we reduced the influence of the previous train. For the first time, we found not only the enhanced amplitude but also the shortened latency for both MMN components when the number of standard stimuli was increased. These findings indicate that both frontal and temporal MMN components reflect the development of memory trace depending on the number of standard stimuli.

[Psychophysiological basis of smells].

There has been an increase in the use of psychophysiological techniques, especially event-related potentials (ERPs) to evaluate the effects of odor on the central nervous system. In the study of ERPs related to odor, there are two main methods of the odor presentation: (1) to investigate the olfactory ERP (OERP) or chemosensory ERP (CSERP), that is to calculate electrophysiological responses to odor stimulation as a trigger; (2) to compare ERP of mental functioning during the odor exposed condition with that of no odor exposure. The amplitude of contingent negative variation (CNV) varies with the odorant being present, when the odor is presented as a trigger and when it is administrated during a task. It is suggested that CNV changes depend on not only the odorant but the anticipation, expectation and emotion of the subject. The latency of the N1 component becomes shorter with increasing concentrations of odors. The N1 amplitude does not depend on the odor concentration while the amplitude of the auditory N1 strongly depends on the stimulus intensity. There is only one report that the olfactory mismatch negativity (MMN) is present in the CSERP. On the other hand, auditory MMN is not affected by odor administration. In relation to the P3 component, rare odors evoked a larger amplitude in contrast to frequent odors, as well as P3 evoked by other modalities. These ERP studies with odors are expected to be applied to such clinical settings as the differentiation between the anosmic patients and normosmic persons, the functional evaluation of patients with brain tumors, the earlier detection of dementia, and the objective evaluation of aromatherapy.

Attentional distraction of CNV depending on the spatial focus.

To investigate the distraction of spatial attention to the task-irrelevant visual stimuli, contingent negative variation (CNV) was measured by using a forewarned reaction time task in 20 healthy subjects. The lasting emission of light, irrelevant to the CNV task, at each perimetric angle of 15 degrees, 30 degrees or 45 degrees to the fixated point was presented to the subjects. The amplitude of early CNV was small only under the light-emission at the angle of 30 degrees. Our results indicate that attention is distracted even by the lasting, task-irrelevant stimuli and that distraction is dependent on the focusing function of attention.