Benign paroxysmal positional vertigo (BPPV) usually resolves in the natural course. Furthermore, therapeutic maneuvers have been reported to accelerate its resolution. However, some patients are annoyed by persistent dizziness and positional nystagmus in their daily lives after conservative treatments, resulting in psychological problems. We have finally identified a surgical treatment strategy for such patients with intractable BPPV, i.e., canal occlusion or canal plugging surgery.We encountered a 28 year-old-man who was diagnosed as having posterior semicircular canal type BPPV, identified by 3D-eye rotation axis analysis during Dix-Hallpike positioning. He had suffered from persistent positional vertigo for more than 10 years despite undergoing various kinds of non-surgical treatments. We performed posterior semicircular canal occlusion surgery for intractable BPPV in this patient, which resulted in successful resolution of the complaints and nystagmus. There were no significant side effects, including sensorineural hearing loss, after the operation.We would like to conclude that the safe and effective option of canal occlusion surgery should be considered for intractable BPPV, although such a condition is very rare (0.23% in our case series). We would also like to emphasize that 3D-eye rotation axis analysis is quite helpful for identifying the affected semicircular canal in BPPV patients.
This paper presents a new reinforcement learning method, called temporal difference learning with Monte Carlo simulation (TDMC), which uses a combination of Temporal Difference Learning (TD) and winning probability in each non-terminal position. Studies on self-teaching evaluation functions as applied to logic games have been conducted for many years, however few successful results of employing TD have been reported. This is perhaps due to the fact that the only reward observable in logic games is their final outcome, with no obvious rewards present in non-terminal positions. TDMC(lambda) attempts to compensate this problem by introducing winning probabilities, obtained through Monte Carlo simulation, as substitute rewards. Using Othello as a testing environment, TDMC(lambda), in comparison to TD(lambda), has been seen to yield better learning results.
We compared neural activation detected by magnetoencephalography (MEG) during tactile presentation of words and non-words in a postlingually deaf-blind subject and six normal volunteers. The left postcentral gyrus, bilateral inferior frontal gyri, left posterior temporal lobe, right anterior temporal lobe, bilateral middle occipital gyri were activated when tactile words were presented to the right hand of the deaf-blind subject. This set of activated regions was not observed in the normal volunteers, although activation of several combinations of these regions was detected. Positron emission tomography confirmed the location of the MEG-activated areas in the deaf-blind subject. Our results demonstrated that the deaf-blind subject is heavily involved in interpreting tactile language by enhancing cortical activation of cognitive and semantic processing.
Motor cortex stimulation (MCS) has been reported to control chronic deafferentation pain successfully. However, the detailed mechanisms of this action have not been made clear. To investigate the possible neural pathways involved in this effect, we measured pre- and post-MCS regional cerebral blood flow (rCBF) using positron emission tomography (PET). Six patients with intractable pain in their left upper extremities were studied. All six were right handed and subdural electrodes were surgically placed over the right primary motor cortex. The rCBF was measured using PET with H215O during pre-MCS conditions of pain and post-MCS conditions of reduced pain. The PET images were analyzed with SPM99 statistical parametric mapping software. The rCBF during pain reduced conditions after MCS increased in left posterior thalamus, left posterior insula, right orbitofrontal cortex, and the left caudal anterior cingulated, when compared to that of the pre-MCS conditions of pain. This result suggests that MCS modulates both pain gait and emotion related pain.
To identify the changes in the respective frequency band and brain areas related to olfactory perception, we measured magnetoencephalographic (MEG) signals before and after instilling intravenously thiamine propyl disulfide (TPD) and thiamine tetrahydrofurfuryl disulfide monohydrochloride (TTFD), which evoked a strong and weak sensation of odor, respectively. For the frequency analysis of MEG, a beamformer program, synthetic aperture magnetometry (SAM), was employed and event-related desynchronization (ERD) or synchronization (ERS) was statistically determined. Both strong and weak odors induced ERD in (1) beta band (13–30 Hz) in the right precentral gyrus, and the superior and middle frontal gyri in both hemispheres, (2) low gamma band (30–60 Hz) in the left superior frontal gyrus and superior parietal lobule, and the middle frontal gyrus in both hemispheres, and (3) high gamma band 2 (100–200 Hz) in the right inferior frontal gyrus. TPD induced ERD in the left temporal, parietal and occipital lobes, while TTFD induced ERD in the right temporal, parietal and occipital lobes. The results indicate that physiological functions in several regions in the frontal lobe may change and the strength of the odor may play a different role in each hemisphere during olfactory perception in humans.
