Shugo Suwazono

Automatic detection method of P300 waveform in the single sweep records by using a neural network.

Event-related potentials (ERPs) are responses related to the recognition of certain stimuli. P300 is the most important positive component in the ERP and appears around 300 ms after the target stimulus in the oddball paradigm. In our previous work, we proposed a method for the automatic detection of the P300 waveform in single-sweep records by using a correlation technique. However, determination of the threshold values of the P300 waveform for the correlation study was not an easy task. In skirting this problem, we developed an automatic method of detecting a single-sweep P300 waveform by using an artificial neural network. We selected appropriate characteristic parameters of positive peaks as input signals for the input layer units, and the weights between the layers were determined by using the back-propagation algorithm. The neural network for P300 detection was obtained automatically, based on the data of ERPs obtained from 11 healthy males, and gave substantial accuracy for P300 detection. Furthermore, by using this neural network we clarified the way in which the P300 waveform is judged visually by each inspector.

Estimate of physiological variability of peak latency in single sweep P300.

Among single sweep records of event-related potentials (ERPs), the peak latency of P300, which is one of the most prominent positive peaks in the ERP obtained in the oddball paradigm, may vary depending on the conditions of the subject. In the analysis of characteristics of the variability in the peak latency, it is important to know to what extent the variability of the measured peak latency (measured variability) is actually caused by physiological factors (physiological variability). In our previous study, a method was developed for judging whether the physiological variability really exists or not, and if it does exist, the developed method extracts the physiological variability from the measured variability based on a limited number of single sweep records. In the present study, based on the P300 waveforms which were detected by blinded visual inspection of the ERP data obtained by an auditory oddball paradigm from 12 healthy adults, the physiological variability was shown to exist with a confidence level of 95% for all subjects. Furthermore, its interval estimate was calculated by subtracting noise variability from the measured variability with a confidence level of 80%, and it was found to range from 17 to 57 ms for all subjects.

THE EFFECTS OF TOBACCO SMOKING ON THE SHORT, MIDDLE, AND LONG LATENCY RESPONSES OF THE BLINK REFLEX IN HUMANS

The three responses (R1, R2, and R3) of the electrically elicited blink reflex (BR) obtained in four normal human subjects were investigated before and after smoking both a filtered and an unfiltered cigarette. The changes observed in the BR were stronger and statistically more significant for the unfiltered than for the filtered cigarette, (p < 0.0001) and were more dramatic in R3 than R1 or R2. The action of nicotine on central pathways located at the interneuronal network of the brainstem, basal ganglia, and C fiber structures involved with this reflex seems to be the most likely mechanism for these findings.

P300 abnormalities in patients with selective impairment of recent memory

We recorded auditory event-related potential (ERP) by using the standard oddball paradigm in seven amnestic patients. Patients were divided into three groups according to brain CT or MRI findings. (1) Three patients with no detectable lesion, including two patients studied during the episode of transient global amnesia, showed a well-defined P300. (2) Three patients with detectable lesions in the mesial temporal lobes did not show any wave form corresponding to P300. In two of these three patients, the ERP wave form showed a significant change in accordance with the improvement of MRI findings. (3) One patient who had a hypothalamic lesion due to total resection of craniopharyngioma showed a low-amplitude P300. Although neuropsychological examinations showed selective and severe impairment of recent memory function in all of these patients, no significant relationship was found between the degree of memory disturbance and P300 abnormality. These results suggest that P300 is more affected by existence and extension of brain lesions, especially in the mesial temporal lobes, rather than degree of memory disturbance. However, these results do not necessarily suggest that the potential generated in the mesial temporal lobes is directly recorded as a component of the scalp-recorded P300.

Auditory event-related potentials in patients with systemic lupus erythematosus.

We studied auditory event-related potentials (ERPs) in 17 patients with systemic lupus erythematosus (SLE). Latencies of N100 and P200 components were normal in all patients, whereas the latencies of target P300 and nontarget P300 components were significantly prolonged in SLE patients with and without cognitive dysfunction. The P300 component of ERPs can be applied to evaluate the cognitive aspects of central nervous system manifestations in SLE patients.

Construction of a morphological filter for detecting an event-related potential P300 in single sweep EEG record in children

A morphological filter for single sweep records of event-related potential (ERP) obtained in an auditory oddball paradigm, especially P300 waveform, was constructed. By combining four basic operations; erosion, dilation, opening and closing, we could derive a desired filter whose properties fit the current objectives. The morphological filter for the single sweep records of ERP was constructed by taking into account the features of the signal and noise components. The morphological filter had superior properties for distinguishing the signal from the noise even when both were within the same frequency band, as in case of children. The constructed morphological filter was evaluated by using the simulation data of ERP and then applied to the actual ERP data obtained from nine normal children. The constructed morphological filter was proved to be an appropriate tool for single sweep analysis of ERP.

Three-tesla magnetic resonance neurography of the brachial plexus in cervical radiculopathy.

Introduction: There have been no reports of the use of 3‐Tesla magnetic resonance neurography (3T MRN) to characterize cervical radiculopathy. In particular, there are no reports of MRN of brachial plexus involvement in patients with cervical radiculopathy. Methods: We reviewed retrospectively 12 consecutive patients with cervical radiculopathy who underwent 3T MRN. Results: The median age was 54.5 years. Eleven of 12 patients were men. The distribution of nerve‐root signal abnormality was correlated with intervertebral foraminal stenosis and the presence of muscles that exhibited weakness and/or signs of denervation on electromyography. MRN abnormalities were found to extend into the distal part of the brachial plexus in 10 patients. Conclusion: This study demonstrates that MRN is potentially useful for diagnosis in patients with suspected cervical radiculopathy. Moreover, the finding of brachial plexus involvement on MRN may indicate a possible pathophysiological relationship between cervical radiculopathy and brachial plexopathy. Muscle Nerve 52:392–396, 2015

Cognitive impairment and quality of life in patients with myotonic dystrophy type 1: Cognition & QoL in DM1

This study sought to clarify whether specific cognitive abilities are impaired in patients with myotonic dystrophy type 1 (DM1) as well as to investigate the relationships among quality of life (QoL), cognitive function, and psychological factors.

Characteristics of auditory P300 in children: application of single trial analysis

As, especially in children, cognitive function might vary from one stimulus to the other, even when the same target stimuli are presented in the oddball paradigm, we applied the single trial analysis adopting discrete Fourier transformation followed by inverse discrete Fourier transformation to the auditory P300 for the first time in children. In 9 children, age 9-13 years, a positive peak was clearly identified in approximately a quarter of the processed single sweep responses to target stimuli (single sweep P300), whereas it was observed less frequently for non-target stimuli. In 2 children of age 6 years, it was difficult to discriminate single sweep P300 from background EEG activities even in the processed data. As for the former group, the detection ratio of P300 in single sweep target responses ranged from 10.0 to 40.0%, and its mean latency and amplitude ranged from 311 to 348 ms and from 31.7 to 41.5 microV, respectively. There was a significant correlation between average data and single sweep data in terms of the P300 latency. However, the amplitude of P300 in the average data bore no relation to the detection ratio, mean amplitude or variability of latency among single sweep P300s. As compared with adult data previously reported, the detection ratio of single sweep P300 was lower and the P300 amplitude was higher in childhood. P300 in children, at least past puberty, can be analyzed by using the single trial method, which is expected to provide more information about the development of human higher brain functions, especially cognitive function.

The natural history of hereditary motor and sensory neuropathy with proximal dominant involvement (HMSN-P) in 97 Japanese patients

Hereditary motor and sensory neuropathy with proximal dominant involvement (HMSN-P) is a motor and sensory neuronopathy with autosomal dominant inheritance, adult onset, slowly progressive course, and is associated with TRK-fused gene (TFG) mutation. At advanced stages, respiratory failure and dysphagia becomes life-threatoning, and patients typically die by their 70s. Although there is currently no evidence for effective treatment, a therapy may be found by elucidation of the function of TFG. Recently its pathomechanism has been proposed to be associated with abnormalities in protein transfer from the endoplasmic reticulum. Such pathomechanisms might involve a similar process in amyotrophic lateral sclerosis; thus, its pathomechanisms and treatment strategy might make it a good model for neurodegenerative disorders. It is of great value to clarify the natural history of HMSN-P, in oder to judge the treatment effect. By evaluating 97 patients (79 out of 97 were examined and all confirmed with p.Pro 285 Leu mutation) in this study, it was confirmed that this disease follows a uniform course in the earlier stages, and there are individual differences in the onset between 20 and 30 years. Such uniformity might be due to the proposed single gene abnormality. At advanced stages, there are larger individual differences in the progression, but the reasons for these are unknown. Longer survival might be achieved with a better care for respiratory failure and dysphagia if such cares were undertaken at appropriate times.