Human Processing of Short Temporal Intervals as Revealed by an ERP Waveform Analysis

To clarify the time course over which the human brain processes information about durations up to ∼300 ms, we reanalyzed the data that were previously reported by Mitsudo et al. (2009) using a multivariate analysis method. Event-related potentials were recorded from 19 scalp electrodes on 11 (nine original and two additional) participants while they judged whether two neighboring empty time intervals – called t1 and t2 and marked by three tone bursts – had equal durations. There was also a control condition in which the participants were presented the same temporal patterns but without a judgment task. In the present reanalysis, we sought to visualize how the temporal patterns were represented in the brain over time. A correlation matrix across channels was calculated for each temporal pattern. Geometric separations between the correlation matrices were calculated, and subjected to multidimensional scaling. We performed such analyses for a moving 100-ms time window after the t1 presentations. In the windows centered at <100 ms after the t2 presentation, the analyses revealed the local maxima of categorical separation between temporal patterns of perceptually equal durations versus perceptually unequal durations, both in the judgment condition and in the control condition. Such categorization of the temporal patterns was prominent only in narrow temporal regions. The analysis indicated that the participants determined whether the two neighboring time intervals were of equal duration mostly within 100 ms after the presentation of the temporal patterns. A very fast brain activity was related to the perception of elementary temporal patterns without explicit judgments. This is consistent with the findings of Mitsudo et al. and it is in line with the processing time hypothesis proposed by Nakajima et al. (2004). The validity of the correlation matrix analyses turned out to be an effective tool to grasp the overall responses of the brain to temporal patterns

An Electroencephalographic Investigation of the Filled-Duration Illusion

The study investigated how the brain activity changed when participants were engaged in a temporal production task known as the “filled-duration illusion.” Twelve right-handed participants were asked to memorize and reproduce the duration of time intervals (600 or 800 ms) bounded by two flashes. Random trials contained auditory stimuli in the form of three 20 ms sounds between the flashes. In one session, the participants were asked to ignore the presence of the sounds, and in the other, they were instructed to pay attention to sounds. The behavioral results showed that duration reproduction was clearly affected by the presence of the sounds and the duration of time intervals. The filled-duration illusion occurred when there were sounds; the participants overestimated the interval in the 600-ms interval condition with sounds. On the other hand, the participants underestimated the 800-ms interval condition without sounds. During the presentation of the interval to be encoded, the contingent negative variation (CNV) appeared around the prefrontal scalp site, and P300 appeared around the parieto-central scalp site. The CNV grew larger when the intervals contained the sounds, whereas the P300 grew larger when the intervals were 800 ms and did not contain the sounds. During the reproduction of the interval to be presented, the Bereitschaftspotential (BP) appeared over the fronto-central scalp site from 1000 ms before the participants’ response. The BP could refer to the decision making process associated with the duration reproduction. The occurrence of three event-related potentials (ERPs), the P300, CNV, and BP, suggests that the fronto-parietal area, together with supplementary motor area (SMA), is associated with timing and time perception, and magnitude of these potentials is modulted by the “filled-duration illusion”

Vection induced by low-level motion extracted from complex animation films

This study examined the contributions of low-, mid- and high-level visual motion information to vection. We compared the vection experiences induced by hand-drawn and computer-generated animation clips to those induced by versions of these movies that contained only their pure optic flow. While the original movies were found to induce longer and stronger vection experiences than the pure optic flow, vection onsets were not significantly altered by removing the mid- and high-level information. We conclude that low-level visual motion information appears to be important for vection induction, whereas mid- and higher-level display information appears to be important for sustaining and strengthening this vection after its initial induction

Detection of deviance in Japanese kanji compound words

Reading fluency is based on the automatic visual recognition of words. As a manifestation of the automatic processing of words, an automatic deviance detection of visual word stimuli can be observed in the early stages of visual recognition. To clarify whether this phenomenon occurs with Japanese kanji compounds-since their lexicality is related to semantic association-we investigated the brain response by utilizing three types of deviants: differences in font type, lexically correct or incorrect Japanese kanji compound words and pseudo-kanji characters modified from correct and incorrect compounds. We employed magnetoencephalography (MEG) to evaluate the spatiotemporal profiles of the related brain regions. The study included 22 adult native Japanese speakers (16 females). The abovementioned three kinds of stimuli containing 20% deviants were presented during the MEG measurement. Activity in the occipital pole region of the brain was observed upon the detection of font-type deviance within 250 ms of stimulus onset. Although no significant activity upon detecting lexically correct/incorrect kanji compounds or pseudo-kanji character deviations was observed, the activity in the posterior transverse region of the collateral sulcus (pCoS)-which is a fusiform neighboring area-was larger when detecting lexically correct kanji compounds than when detecting pseudo-kanji characters. Taken together, these results support the notion that the automatic detection of deviance in kanji compounds may be limited to a low-level feature, such as the stimulus stroke thickness.Peer reviewe

A coherence analysis of EEG response to speech modulated by m-sequence

We have developed a technique for assessment of natural verbal comprehension, using electroencephalography (EEG) and m-sequence modulation (Takeichi et al., Neuroscience Research, 57, 314-318). The technique is superior to the conventional averaging methods in that it is less susceptible to measurement artifacts, efficient without repeated presentations for signal averaging, and suitable for non-time-locked continuous mental processes. Scalp EEGs were recorded from eight right-handed Japanese speakers while they were listening to 51s-long news, in Japanese and Spanish, with and without modulation in amplitude timed by an m-sequence (a binary pseudorandom sequence). Correlation functions were computed between the m-sequence and the EEG. Then, independent component analysis (ICA, AMUSE, delta=1) was applied to the correlation functions to find critical components to discriminate between comprehensible and incomprehensible stimuli. In the present study, we focused on the EEG coherence between recording electrodes. The original EEGs were convolved with the Fourier transform of the critical ICA component function, in order to maintain only the critical component. Coherence values were computed for each electrode pair and individual frequency bands including theta, alpha, beta, gamma, and were averaged across subjects for each frequency band. The coherence value for the Japanese speech without modulation increased between T7 (left temporal) and the other electrodes in the alpha (4-13Hz) band. For the modulated Japanese coherence increased between T7 (left temporal) and the other electrodes, and F8 (right frontal) with other electrodes in the high-gamma (70-100Hz) band. Such coherence changes were not found for either nonmodulated or modulated Spanish speech

Novel method of extracting motion from natural movies

tBackground: The visual system in primates can be segregated into motion and shape pathways. Interactionoccurs at multiple stages along these pathways. Processing of shape-from-motion and biological motionis considered to be a higher-order integration process involving motion and shape information. However,relatively limited types of stimuli have been used in previous studies on these integration processes.New method: We propose a new algorithm to extract object motion information from natural movies andto move random dots in accordance with the information. The object motion information is extracted byestimating the dynamics of local normal vectors of the image intensity projected onto the x-y plane ofthe movie.Results: An electrophysiological experiment on two adult common marmoset monkeys (Callithrix jacchus)showed that the natural and random dot movies generated with this new algorithm yielded comparableneural responses in the middle temporal visual area.Comparison with existing methods: In principle, this algorithm provided random dot motion stimuli con-taining shape information for arbitrary natural movies. This new method is expected to expand theneurophysiological and psychophysical experimental protocols to elucidate the integration processingof motion and shape information in biological systems.Conclusions: The novel algorithm proposed here was effective in extracting object motion informationfrom natural movies and provided new motion stimuli to investigate higher-order motion informationprocessing.© 2017 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license(http://creativecommons.org/licenses/by/4.0/)