Hisashi Toyoshima

Spatiotemporal Human Brain Activities by Visual Stimulus of Directional Characters and Symbols

To investigate the brain activity during human recognition of characters and symbols with directional meanings, the authors recorded electroencephalograms (EEGs) from subjects in viewing four types of Kanji (Chinese characters being used currently in the Japanese language) and four arrows presented on the CRT which means direction for Upward, Downward, Leftward and Rightward. As a result, the reaction time for each direction was almost equal, when characters or arrows were presented, regardless of the directions. However, for all the directions, the latency of peak for character was longer than that for arrow. The latency of peak for the word meaning upward or downward was a little shorter than those for other characters. EEGs were averaged for each stimulus type, and event-related potentials (ERPs) were determined. Tendencies in ERPs were compared, and marked changes in amplitude were seen near a latency of 420 ms for (upward) and (downward) and 500 ms for (leftward) and (rightward). Marked changes in amplitude were seen near a latency of 500 ms for all arrow symbols. When comparing ERPs between kanji characters and arrow symbols, differences in latency were noted, as were similarities in marked amplitude changes. When comparing ERPs between kanji characters and arrow symbols with opposing meanings, peak latencies for marked amplitude changes were predominantly similar, but polarities were opposite. Peak latency of ERPs was subjected to equivalent current dipole source localization (ECDL). ECD was estimated at a latency of around 110 ms in the MT field and then around 300 ms in the precentral gyrus. No marked differences in this tendency were noted among the eight stimuli. After ECD was estimated in the precentral gyrus, with the kanji characters, ECD was estimated in the right middle temporal gyrus regardless of direction. ECD was then estimated in areas related to language, such as the Wernickes area in the left middle temporal gyrus, the left angular gyrus and the left lingual gyrus. ECD was later estimated in the left middle frontal gyrus, left inferior frontal gyrus and prefrontal area. ECD was estimated in the precentral gyrus just before the amplitude of ERPs changed markedly. With arrow symbols, ECD was estimated in the right middle temporal gyrus, and then ECD was estimated in areas related to working memory for spatial perception, such as the right inferior or right middle frontal gyrus. Then, as with kanji characters, ECD was estimated in the prefrontal area and precentral gyrus.

Brain computer interface by use of electroencephalograms from right frontal area

In order to develop a brain computer interface (BCI), some of the present authors have investigated the brain activity during human recognition of characters and symbols representing directional meaning. They have recorded electroencephalograms (EEGs) from subjects viewing four types of arrows: “↑”, “↓”, “←” and “→” that were presented on a CRT. The arrows denote direction for upward, downward, leftward and rightward, respectively. Subjects were asked to read them silently. EEGs were averaged for each stimulus type and direction, and event related potentials (ERPs) were obtained. The equivalent current dipole source localization (ECDL) method has been applied to these ERPs. In both cases, ECDs were localized to areas related to the working memory for spatial perception, i. e. the right upper or the right middle frontal areas. And the opposite directional arrows had opposite dipoles in these areas. Taking into account these facts, the authors investigated a single trial EEGs of the subject precisely after the latency at 400ms, and determined effective sampling latencies for the discriminant analysis to four types of arrows. We sampled EEG data at latencies from 400ms to 900ms at 25ms intervals by the four channels such as Fp2, F4, C4 and F8. Data were resampled −1ms and −2ms backward. Results of the discriminant analysis with jack knife method for four types objective variates, the mean discriminant rate for seven sample subjects was almost 85 %.

Localization of brain activity during perception of circle movement by use of equivalent current dipole analysis

A moving white circle on a CRT was presented to subjects. Moving patterns were downward, upward, rightward and leftward. A random movement of the circle was presented to subjects in comparison of other movements. These five movements were presented at random to the subjects. Meantime, electroencephalograms were recorded. The data was summed in each movement and the equivalent current dipole localization (ECDL) was done to estimate the source. From the results, the dipoles was estimated on the MT at latency from 80 ms to 120 ms, and after on the intraparietal sulcus, on the precentral gyrus and on the frontal eye field.

Recognition of perception and the localization for aperture problem in visual pathway of brain

The aperture problem is the one of the experiments to analyze binding mechanism of the space recognition with the human visual pathway. Nishina has already insisted that recognition of visual perception by the aperture problem depends in display time. In this paper, we discuss how other experimental parameters, e.g., radius, distance between circles, and speed of bar depend with recognition rate by measurement analysis of the perception. We simultaneously estimate the reaction latency of the perception by electroencephalograms (EEG) analysis, and we localize the brain activity area by equivalent current dipole (ECD). We then discuss the relationship between the reaction latency of the visual evoked potential (VEP), event related potential (ERP) and the localized equivalent current dipole (ECD) in the visual pathway. By these discussion, we concluded that perception would be localized with the prefrontal lobe.

Discrimination of Electroencephalograms on Recognizing and Recalling Playing Cards—A Magic Without Trick

Authors measured electroencephalograms (EEGs) as participants recognized and recalled 13 playing card images (from ace to king of club) presented on a CRT monitor. During the experiment, electrodes were fixed on the scalps of the participants. Four EEG channels located over the right frontal and temporal cortices (Fp2, F4, C4 and F8 according to the international 10–20 system) were used in the discrimination. Sampling data were taken at latencies between 400 and 900 ms at 25 ms intervals for each trial. Thus, data were 84 dimensional vectors (21 time point X 4 channels). The number of objective variables was 13 (the number of different cards), and the number of explanatory variates was thus 84. Canonical discriminant analysis was applied to these single trial EEGs. Results of the canonical discriminant analysis were obtained using the jack knife method and were 100% of nine participants. We could perform playing card estimation magic without a trick. This fact is sub production based on our series of precedent research.

Spatiotemporal human brain activities on recalling 4-legged mammal and fruit names

The authors have measured electroencephalograms (EEGs) from subjects observing images of 4-legged mammal and/or fruit, and recalling their name silently. The equivalent current dipole source localization (ECDL) method has been applied to the induced event related potentials (ERPs): averaged EEGs. The equivalent current dipoles (ECDs) were localized to the primary visual area V1 around 100ms, to the ventral pathway (TE) around 270ms, to the parahippocampal gyrus (ParaHip) around 380ms. Then ECDs were localized to the Brocas area around 450ms, to the fusiform gyrus (FuG) around 600ms, and again to the Brocas area around 760ms. According to the previous researches, the process of search and preservation in the memory is presumed to be done in the ParaHip. From the results of the present experiment, the authors supposed that both long shape and round shape visual stimuli are processes by Wernickes area, but only long shape pass through angular gyrus (AnG) before arriving at Wernickes area.

Brain Computer Interface by Use of Single Trial EEG on Recalling of Several Images

In order to develop a brain computer interface (BCI), the present authors investigated the brain activity during recognizing or recalling some images of line drawings. The middle frontal robe is known to be related to the function of central executive system on working memory. It is supposed to be so called headquarters of the higher order function of the human brain.Taking into account these facts, the authors recorded Electroencephalogram (EEG) from subjects looking and recalling four types of line drawings of body part, tetra pod, and further ten types of tetra pods, home appliances and fruits that were presented on a CRT. They investigated a single trial EEGs of the subjects precisely after the latency at 400ms, and determined effective sampling latencies for the discriminant analysis to some types of images. They sampled EEG data at latencies from 400ms to 900ms at 25ms intervals by the four channels such as Fp2, F4, C4 and F8. Data were resampled -1 ms and -2 ms backward. Results of the discriminant analysis with the jack knife (cross validation) method for four type objective variates, the discriminant rates for two subjects were more than 95%, and for ten objective variates were almost 80%.

Spatiotemporal human brain activities on recalling body parts

The authors measured electroencephalograms (EEGs) from subjects looking at line drawings of body parts and recalling their names silently. The equivalent current dipole source localization (ECDL) method is applied to the event related potentials (ERPs): summed EEGs. ECDs are localized to the primary visual area VI, to the ventral pathway (ITG: Inferior Temporal Gyrus), to the parahippocampus (ParaHip), the right angular gyrus (AnG), to the right supramarginal gyrus (SMG) and to the Wernikes area. Then ECDs are localized to the Brocas area, to the postcentral gyrus (PstCG) and to the fusiform gyrus (FuG), and again to the Brocas area. These areas are related to the integrated process of visual recognition of pictures and the retrieval of words. Some of these areas are also related to image recognition and word generation. And process of search and preservation in the memory is done from the result of some ECDs to the paraHip.

A Measure of Localization of Brain Activity for the Motion Aperture Problem Using Electroencephalograms

When viewed through a limited-sized aperture, bars appear to move in a direction normal to their orientation. This motion aperture problem is an important rubric for analyzing the early stages of visual processing particularly with respect to the perceptual completion of motion sampled across two or more apertures. In the present study, a circular aperture was displayed in the center of the visual field. While the baseline bar moved within the aperture, two additional circular apertures appeared; within each aperture, a “flanker bar” appeared to move. For upwards movement of the flanker lines, subjects perceived the flanker bar to be connected to the base bar, and all three parts to move upward. The authors investigated the motion perception of the moving bars by changing the line speeds, radii of the apertures, and distances between the circular apertures and then analyzed spatio-temporal brain activities by electroencephalograms (EEGs). Latencies in the brain were estimated by using equivalent current dipole source (ECD) localization for one subject. Soon after the flankers appear, ECDs, assumed to be generated by the recognition of the aperture’s form, were localized along the ventral pathway. After the bars moved, the ECDs were localized along the dorsal pathway, presumably in response to motion of the bars. In addition, for the perception of grouped motion and not normal motion, ECDs were localized to the middle frontal gyrus and the inferior frontal gyrus. DOI: 10.4018/978-1-4666-2539-6.ch009

Fundamental research for brain machine interface by use of EEG from right frontal gyrus

In order to develop a brain machine interface, the authors have investigated the brain activity during human recognition of characters and symbols representing directional meaning. The authors have recorded electroencephalograms (EEGs) from subjects viewing four types of Kanji (Chinese characters being used currently in the Japanese language) and arrows that were presented on a CRT. Each denoted direction for upward, downward, leftward and rightward, respectively. Subjects were asked to read them silently. Regardless of the directions, the reaction time was almost equal. EEGs were averaged for each stimulus type and direction, and event related potentials (ERPs) were obtained. The equivalent current dipole source localization (ECDL) method has been applied to these ERPs. In both cases, no large difference was observed until 250 ms at their latencies, and after that ECDs were localized to areas related to the working memory for the spatial perception. Taking into account these facts, the authors have investigated a single trial EEGs precisely after the latency at 400ms, and have determined effective sampling latencies for the discriminant analysis on four types of arrows: ↑, ↓, ← and →. By a discriminant analysis, the results of discriminant rate are 100% for each subject and for each trial. These results show the possibility of using EEGs for a brain machine interface in four type controls.