Kaori Tamura

VCIP135 deubiquitinase and its binding protein, WAC, in p97ATPase‐mediated membrane fusion

Two distinct p97 membrane fusion pathways are required for Golgi biogenesis: the p97/p47 and p97/p37 pathways. VCIP135 is necessary for both pathways, while its deubiquitinating activity is required only for the p97/p47 pathway. We have now identified a novel VCIP135‐binding protein, WAC. WAC localizes to the Golgi as well as the nucleus. In Golgi membranes, WAC is involved in a complex containing VCIP135 and p97. WAC directly binds to VCIP135 and increases its deubiquitinating activity. siRNA experiments revealed that WAC is required for Golgi biogenesis. In an in vitro Golgi reformation assay, WAC was necessary only for p97/p47‐mediated Golgi reassembly, but not for p97/p37‐mediated reassembly. WAC is hence thought to function in p97/p47‐mediated Golgi membrane fusion by activating the deubiquitinating function of VCIP135. We also showed that the two p97 pathways function in ER membrane fusion as well. An in vitro ER reformation assay revealed that both pathways required VCIP135 but not its deubiquitinating activity for their ER membrane fusion. This was consistent with the finding that WAC is unnecessary for p97‐mediated ER membrane fusion.

Phosphorylation of p37 is important for Golgi disassembly at mitosis

In mammals, the Golgi apparatus is disassembled at early mitosis and reassembled at the end of mitosis. For Golgi disassembly, membrane fusion needs to be blocked. Golgi biogenesis requires two distinct p97ATPase-mediated membrane fusion, the p97/p47 and p97/p37 pathways. We previously reported that p47 phosphorylation on Serine-140 by Cdc2 results in mitotic inhibition of the p97/p47 pathway [11]. In this study, we demonstrate that p37 is phosphorylated on Serine-56 and Threonine-59 by Cdc2 at mitosis, and this phosphorylated p37 does not bind to Golgi membranes. Using an in vitro Golgi reassembly assay, we show that mutated p37(S56D, T59D), which mimics mitotic phosphorylation, does not cause any cisternal regrowth, indicating that p37 phosphorylation inhibits the p97/p37 pathway. Our results demonstrate that p37 phosphorylation on Serine-56 and Threonine-59 is important for Golgi disassembly at mitosis.

Isolation of a point-mutated p47 lacking binding affinity to p97ATPase.

MINT‐7987326: p97 (uniprotkb:P46462) binds (MI:0407) to p37 (uniprotkb:Q0KL01) by pull down (MI:0096)

Phase-locked theta activity evoked in patients with severe motor and intellectual disabilities upon hearing own names

BACKGROUND Severe motor and intellectual disability (SMID) patients cannot express their feelings with language. Understanding what they are thinking about or how they feel is thus difficult. This study focused on brain responses to hearing their own names to clarify the situation in these patients. METHODS We performed and analyzed electroencephalography (EEG) for six patients with SMID and eleven healthy subjects. All subjects were presented with auditory stimuli including calling the subjects own name (SON) and reading words. EEG was analyzed by time-frequency analysis, event-related spectral perturbation (ERSP) to detect EEG power changes caused by EEG amplitude, and inter-trial coherence (ITC) to investigate phase-locked changes. RESULTS ERSP results from healthy subjects showed significant theta power increases as a specific response to SON. While we could not identify a similar pattern in the responses of patients with SMID, analysis of ITC revealed that theta phase-locked activity increased in response to SON not only in all healthy subjects, but also in four patients. DISCUSSION These results indicate that theta phase-locked activity in some patients with SMID was strongly associated with SON, as in healthy subjects. Our study suggests the existence of specific neural markers that signal an attentional shift in patients upon hearing SON.

EEG-based evaluation for perception-assist in upper-limb power-assist exoskeletons

In this paper, we report an attempt to utilize Electroencephalography (EEG) signals for judging the correctness of the performed perception-assist in an upper-limb power-assist exoskeleton. Although Electromyography (EMG) signals can be used for judgments, lack of change in EMG signals and the complexity of the upper-limb motions sometimes make it difficult to evaluate the perception-assist using EMG signals. In this study, we investigate whether EEG signals can alone be used instead of EMG signals to judge the correctness of the perception-assist performed by the exoskeleton. Experiments are carried out with three healthy subjects and the results are presented in this paper. Moreover, we show the potentials and advantages of using EEG signals recorded from brain of the users to judge correctness of the perception-assist in upper-limb power-assist exoskeletons.

Estimation of user's hand motion based on EMG and EEG signals

A surface EMG signal is one of the most widely used signals as input signals to wearable robots. However, EMG signals that are used to estimate motions are not always available to all users. On the other hand, an EEG signal has drawn attention as input signals for those robots in recent years. The EEG signals can be measured even with amputees and paralyzed patients who are not able to generate some EMG signals. However, the measured EEG signal does not have one-to-one relationships with the corresponding brain part. Therefore, it is more difficult to find the required signals for the control of the robot in accordance with the intention of the users motion using the EEG signals compared with that using the EMG signals. In this paper, both the EMG and EEG signals are used to estimate the users motion intention. In the proposed method, the EMG signals are used as main input signals because the EMG signals have higher relative to the motion of a user in comparison with the EEG signals. The EEG signals are used as sub signals in order to cover the estimation of the intention of the users motion when all required EMG signals cannot be measured. The effectiveness of the proposed method has been evaluated by performing experiments.

Estimation of joint force/torque based on EMG signals

Dislocation of an artificial hip joint is one of the most serious problems for Total Hip Arthroplasty (THA). In order to analyze the phenomenon of the artificial hip joint dislocation, a hip joint simulator has been developed. Although the hip joint motion and the hip joint contact force (the resultant muscle force around muscles of hip joint and the floor reaction force) during the daily life motion must be realized by the simulator, the resultant muscle force around hip joint can not be prepared easily. In this paper, a method to estimate the resultant muscle force around hip joint based on EMG (electromyogram) signals is proposed. Since the proposed estimation method requires only the measurement of EMG signals, the resultant muscle force can be estimated easily. The effectiveness of the proposed estimation method was evaluated by performing the experiments.

Olfactory modulation of colour working memory: How does citrus-like smell influence the memory of orange colour?

Olfactory modulation of vision is not well understood whereas visual modulation of olfaction has been more fully investigated. This study aimed to reveal in a simple manner whether there is olfactory modulation of colour working memory using an odour that induces a citrus-like smell and is associated with orange colours. We assumed that the odour would have modulatory effects on the colour information stored in working memory. To clarify whether these effects are supportive or disruptive, during the colour working memory task we measured an event-related potential component, P3, which is involved in attentional processes of working memory. The results indicated that odour presentation mediated a decline in the rate of correct guesses for orange colours. Furthermore, the odour suppressed P3 during reddish-colour retrieval, including orange. These results suggest that colour working memory in orange can be disrupted via olfactory modulation with citrus-like odours.

Physiological activity in calm thermal indoor environments

Indoor environmental comfort has previously been quantified based on the subjective assessment of thermal physical parameters, such as temperature, humidity, and airflow velocity. However, the relationship of these parameters to brain activity remains poorly understood. The objective of this study was to determine the effect of airflow on brain activity using electroencephalograms (EEG) of participants in a living environment under different airflow conditions. Before the recording, the room was set to a standardised air temperature and humidity. During the recording, each participant was required to perform a simple time-perception task that involved pressing buttons after estimating a 10-second interval. Cooling and heating experiments were conducted in summer and winter, respectively. A frequency analysis of the EEGs revealed that gamma and beta activities showed lower amplitudes under conditions without airflow than with airflow, regardless of the season (i.e., cooling or heating). Our results reveal new neurophysiological markers of the response to airflow sensation. Further, based on the literature linking gamma and beta waves to less anxious states in calm environments, we suggest that airflow may alter the feelings of the participants.

Evaluation of cognitive function when hearing one's own name in patients with brain injuries in early developmental stages.

Purpose: The level of residual cognitive function in patients with early brain injury is a key factor limiting rehabilitation and the quality of life. Although understanding residual function is necessary for appropriate rehabilitation, the extent of its effects on cognitive improvement remains unknown. This study evaluated cognitive function in patients with severe motor and intellectual disabilities after early brain injuries due to cerebral hemorrhage or periventricular leukomalacia. We focused on neural responses to hearing the subjects own name (SON). According to previous studies, differences in response to SON are associated with several types of cognitive dysfunction. Methods: We examined healthy subjects (aged 21.4 ± 1.10 years; control) and patients with a previous brain injury (aged 13–27 years at the time of our analysis) resulting in periventricular leukomalacia or a cerebral hemorrhage during the perinatal period or childhood. We recorded EEG responses to the SON and to other Japanese words, obtaining EEG-evoked potentials with wavelet transformations. Results: Compared with healthy controls, beta power (not alpha power) revealed differences in response to SON by patients with brain injury, especially those with cerebral hemorrhage. Conclusions: We suggest that alpha and beta power differences reflect different cognitive functions and that the SON response reveals more than one process. Beta powers may reflect the intellectual disability of cognitive function in response to self-relevant stimuli, especially in patients with cerebral hemorrhage. Meanwhile, alpha powers did not differ from those of the healthy controls, suggesting that the patients perhaps paid attention to their own names.