Decoding Different Reach-and-Grasp Movements Using Noninvasive Electroencephalogram

Grasping is one of the most indispensable functions of humans. Decoding reach-and-grasp actions from electroencephalograms (EEGs) is of great significance for the realization of intuitive and natural neuroprosthesis control, and the recovery or reconstruction of hand functions of patients with motor disorders. In this paper, we investigated decoding five different reach-and-grasp movements closely related to daily life using movement-related cortical potentials (MRCPs). In the experiment, nine healthy subjects were asked to naturally execute five different reach-and-grasp movements on the designed experimental platform, namely palmar, pinch, push, twist, and plug grasp. A total of 480 trials per subject (80 trials per condition) were recorded. The MRCPs amplitude from low-frequency (0.3–3 Hz) EEG signals were used as decoding features for further offline analysis. Average binary classification accuracy for grasping vs. the no-movement condition peaked at 75.06 ± 6.8%. Peak average accuracy for grasping vs. grasping conditions of 64.95 ± 7.4% could be reached. Grand average peak accuracy of multiclassification for five grasping conditions reached 36.7 ± 6.8% at 1.45 s after the movement onset. The analysis of MRCPs indicated that all the grasping conditions are more pronounced than the no-movement condition, and there are also significant differences between the grasping conditions. These findings clearly proved the feasibility of decoding multiple reach-and-grasp actions from noninvasive EEG signals. This work is significant for the natural and intuitive BCI application, particularly for neuroprosthesis control or developing an active human–machine interaction system, such as rehabilitation robot.

The Effect of Rhythmic Tactile Stimuli Under the Voluntary Movement on Audio-Tactile Temporal Order Judgement

The simultaneous perception of multimodal sensory information is important for effective reactions to the external environment. In relation to the effect on time perception, voluntary movement and rhythmic stimuli have already been identified in previous studies to be associated with improved accuracy of temporal order judgments (TOJs). Here, we examined whether the combination of voluntary movement and rhythmic stimuli improves the just noticeable difference (JND) in audio-tactile TOJ Tasks. Four different experimental conditions were studied, involving two types of movements (voluntary movement, involuntary movement) and two types of stimulus presentation (rhythmic, one-time only). In the voluntary movement condition (VM), after the auditory stimulus (cue sound) participants moved their right index finger voluntarily and naturally, while in the involuntary movement condition (IM), their right index finger was moved by the tactile device. The stimuli were provided in a rhythmic or one-time only manner by hitting inside the first joint of the participants' right index finger using a tactile device. Furthermore, in the rhythmical tactile (RT) conditions, tactile stimuli were presented rhythmically to the right index finger 5 times consecutively. On the other hand, in the one-time tactile (1T) conditions, tactile stimuli was presented one-time only to the right index finger. Participants made an order judgment for the fifth tactile stimuli and the first and only auditory stimuli. In our TOJ tasks, auditory-tactile stimulus pairs were presented to participants with varying stimulus-onset asynchronies (SOAs; intervals between the within-pair onsets of the auditory and tactile stimuli). For the two stimuli presented at a time that were shifted by the SOA, the participants were asked to judge which one was presented first, and they were given a two-choice answer. Using a non-parametric test, our results showed that voluntary movement and rhythmic tactile stimuli were both effective in improving the JNDs in TOJ Tasks. However, in the combination of voluntary movement and rhythmic tactile stimuli, we found that there was no significant difference in JNDs in our experiments.

The moving learner: Object manipulation in VR improves vocabulary learning

A challenging part of foreign language acquisition is learning new vocabulary. Research has demonstrated the benefits of motor action to vocabulary learning, though these findings are rarely translated into teaching and learning practices. In this work we present a novel paradigm for vocabulary learning in a virtual reality environment, capitalizing on the prominent advantages of this technology as an ‘embodied’ learning tool. Hebrew-speaking adults explored a virtual room and learned the Finnish names of 40 daily objects. Every participant learned the new object names under 3 conditions: (1) Watch-only: watching the object without performing any movement (2) performing an irrelevant movement, or (3) performing a manipulation movement that implied its habitual use. Participants completed a word-picture matching test after each training block, as well as additional word-picture matching and recall tests a week after the initial training session. The overall results demonstrate improved comprehension rates for items that were learned in the manipulation movement condition compared to the irrelevant movement condition, both in the initial learning session and one week following it. These initial findings suggest that VR technology may indeed hold the potential to offer a more authentic, multisensory and motor context to efficient foreign language learning.

Attribution of mental states in glossolalia: a direct comparison with schizophrenia

Glossolalia (“speaking in tongues”) is a rhythmic utterance of pseudo-words without constant semantic and syntactic properties. Although glossolalia is a culturally embedded religious activity, its connection with psychopathology (e.g., psychotic thought disorder, and altered mental state attribution) is still a matter of debate. We investigated 31 glossolalists, 31 matched control subjects, and 31 patients with schizophrenia using the Animated Triangles Test (ATT) and the Reading the Mind in the Eyes Test (RMET). The ATT can detect hypo- and hypermentalization using animations of two moving triangles. Healthy adults describe these as random movements (e.g., bouncing), willed actions (e.g., playing), or they mentalize (e.g., tricking). We found that glossolalists provided more mentalizing descriptions in the ATT random and intentional movement animations relative to the control subjects. They also recognized more mental states on the RMET than the controls. None of them had a diagnosis of mental disorders. In contrast, patients with schizophrenia hypermentalized only in the ATT random movement condition, whereas they showed hypomentalization in the intentional movement condition and RMET relative the control subjects. ATT hypermentalization in the glossolalia group selectively correlated with intrinsic religiosity. Our results therefore demonstrated a substantial difference in the mentalizing activity of glossolalists (generalized hypermentalization) and patients with schizophrenia (both hypo- and hypermentalization).

Float-Over Installation Analysis of Semisubmersible Production Platform Topside

Compared with split lifting by floating crane, the float-over is less time-consuming and has larger lifting capacity, especially suitable for large and medium sized offshore platforms. Float-over installation process of a deepwater semisubmersible platform topside is analyzed in this paper. And the multi-floating coupling calculation is carried out in the typical loading conditions of mating process between topside and column top structure. The motion response of leg mating unit in position of barge is received. The calculation results show that the float movement condition meets float-over installation requirements of topside. The analysis can provide a reference for the project of the float-over installation in the future.

Effect of Acute Physical Activity on Interval Timing

Timing is an integral part of physical activities. Walking as a routine form of physical activity might affect interval timing primarily in two different ways within the pacemaker–accumulator timing-theoretic framework: (1) by increasing the speed of the pacemaker due to its physiological effects; (2) by decreasing attention to time and consequently slowing the rate of temporal integration by serving as a secondary task. In order to elucidate the effect of movement on subjective time, in two different experiments we employed a temporal reproduction task conducted on the treadmill under four different encoding–decoding conditions: (1) encoding and reproducing (decoding) the duration while standing (rest); (2) encoding the duration at rest and reproducing it while moving: (3) both encoding and reproducing the duration while moving; and (4) encoding the duration while moving and reproducing it at rest. In the first experiment, participants were tested either in the 4 or the 8 km/h movement condition, whereas in the second experiment a larger sample was tested only in the 4 km/h movement condition. Data were de-trended to control for long-term performance drifts. In Experiment 1, overall durations encoded at rest and reproduced during motion were under-reproduced whereas durations encoded during motion and reproduced at rest were over-reproduced only in the 8 km/h condition. In Experiment 2, the same results were observed in the 4 km/h condition with a larger sample size. These effects on timing behavior provide support for the clock speed-driven effect of movement and contradicts the predictions of attention-based mediation.

SlamTracker Accuracy under Static and Controlled Movement Conditions

Accelerometry is the de facto standard in objective physical activity monitoring. However traditional accelerometer units undergo proprietary pre-processing, resulting in the ‘black-box’ phenomenon, where researchers are unaware of the processes and filters used on their data. Raw accelerometers where all frequencies related to human movement are included in the signal, would facilitate novel analyses, such as frequency domain analysis and pattern recognition. The aim of this study was to quantify the mean, standard deviation and variance of the SlamTracker raw accelerometer at a range of speeds. Four tri-axial accelerometers underwent a one minute static condition test nine movement condition tests. Accelerometers were assessed for mean, standard deviation, sample variance and coefficient of variation throughout in all axes for all experimental conditions. The sample variance was <0.001g across all speeds and axes during the movement condition tests. In conclusion, the SlamTracker is shown to be an accurate and reliable device for measuring the raw accelerations of movement.