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P1-15 Face-sensitive neural responses in the occipital cortex without visual awareness
S104 face of 18 persons (8 males and 10 females). Frontal and deviated faces were presented with a fixed gaze direction, followed by an apparent movement of eyes either toward the subject or away from the subject. Furthermore, eyes photographs with the apparent motion cut out from the face were also used as the stimulus. Subjects were eighteen student volunteers (8 males and 9 females). In ‘Direct gaze condition’, gaze direction moved toward the subject either from 30 degrees right or left location, and in ‘Averted gaze condition’, it moved away 30 degrees either right or left direction from the subject. EEG were recorded from Fz, Cz, Pz, C3, C4, T3, T4, T5 and T6 locations referred to nose-tip. The negative ERP component about 170 ms after stimulus onset (N170) were observed to the apparent movement of eyes both for face and eyes stimulus. This component was larger in ‘Direct gaze condition’ than in ‘Averted gaze condition’, suggesting that gaze contact relates to the specific processing different from averted gaze. Furthermore this N170 was interacted with the diretion of face. P1-14 Facial identity facilitates facial expression recognition: A high-density ERP study S. Komatsu1,2 , K. Ogata1 , S. Horie1 , Y. Hakoda2 , S. Tobimatsu1 Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan, 2 Graduate School of Human-Environment Studies, Kyushu University, Fukuoka, Japan
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Objective: It is assumed that the processing of facial expression and facial identity are independent each other. However, in recent psychological studies with a modified selective attention task, there is asymmetric dependency between these processes, and it is shown that facial identity influences facial expression recognition. The purpose of this study was to examine the effect of facial identity on facial expression recognition by recording event-related potentials (ERPs) with a modified selective attention task. Methods: Twenty normal adults participated in this study. Two male faces with angry or happy expressions were presented for 500 ms. Participants were asked to make a rapid judgment of these facial expressions under two different identity conditions. The baseline condition stipulated that participants judged facial expressions while the identity was held constant. As the filtering condition, participants judged facial expressions while the identity was varied randomly. ERPs were recorded by 128 electrodes during the presentation of the expressions. Results: We focused on the N170 component which is related to the structural encoding of faces and not modulated by emotional expressions in many studies. Topographical maps of grand averaged ERPs revealed that the N170 was recorded in a time window between 120 and 190 ms in the lateral occipito-temporal area. The N170 amplitude was significantly larger for angry faces than for happy faces, and larger under the baseline condition than under the filtering condition. Also the N170 latency was significantly longer under the baseline condition than under the filtering condition. Conclusions: These results suggest that the N170 is modulated by facial expressions and the identity condition. Therefore, we conclude that facial identity influences ERPs during facial expression recognition.
Posters Results: The amplitude of the occipital P1 (120 ms) and N1 (160 ms) for subthreshold faces was significantly different from those for objects. Specifically, the P1 amplitude elicited by upright faces was significantly larger than for inverted faces. The occipital N1 amplitude for faces was smaller than for objects. In contrast, the amplitude of the occipitotemporal N170 for faces but not for objects was significantly greater in the threshold and supra-threshold conditions. Conclusions: Our results suggest that the P1 and N1 have differential effects on early-stage unconscious face recognition, whereas the N170 reflects conscious face recognition. Significance: Even subthreshold faces were processed unconsciously at an early visual stage, suggesting a sequential pathway of information processing that proceeds to facespecific processing mechanisms. P1-16 An electrophysiological investigation of the emotional influence on the breadth of attention at early sensory processing stages H. Moriya1,2 , T. Kasai3 , H. Nittono1 Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan, 2 Graduate School of Education, Hokkaido University, Hokkaido, Japan, 3 Faculty of Education, Hokkaido University, Hokkaido, Japan 1
Objective: It has been suggested that emotional states modulate the breadth of attentional focus. However, it remains unclear which processing stage is responsible for this effect. Evidence from research using event-related brain potentials (ERPs) suggests that the P1 component evoked by attended visual stimuli reflects the focus of attention at early sensory processing stages. In this study, we recorded ERPs to examine whether emotional states influence the breadth of attentional focus at early stages. Methods: Twelve university students participated in the experiment. To induce negative, neutral, and positive emotional states, participants viewed affective pictures before a selective attention task. In the selective attention task, two letter pairs were presented in the left and right visual fields. In most trials, unmatched letter pairs (e.g., TL) were presented in both visual fields (standard stimuli, p = 0.80). In the other trials, a matched letter pair (e.g., SS) was presented at either the left or right visual field (target stimuli; p = 0.10, respectively). After viewing affective pictures, participants directed their attention to the left or right visual field and detected a target stimuli presented at the attended visual field. ERPs were recorded from 25 scalp electrodes. Results: Subjective ratings indicated that the presentation of affective pictures induced negative and positive emotional states. The P1 evoked by standard stimuli at occipitotemporal sites was more positive over the hemisphere contralateral to the attended visual hemifield. This contralateral preponderance effect has been assumed to reflect the attentional gain control mechanism of the visual cortices. However, this P1 attention effect did not differ between the negative, neutral, and positive emotional conditions. Conclusions: The results suggest that emotional states do not modulate the breadth of attentional focus at early visual processing stages, at least when the direction of attention is specified by instructions.
P1-15 Face-sensitive neural responses in the occipital cortex without visual awareness
P1-17 Mechanism of head shaking nystagmus from focal cerebellar lesions: flocculonodular dysfunction
T. Mistudo1 , Y. Kamio2 , Y. Goto3 , T. Nakashima1 , S. Tobimatsu1 1 Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan, 2 Department of Child and Adolescent Mental Health, National Institute of Mental Health, National Center of Neurology and Psychiatry, Kodaira, Japan, 3 Department of Occupational Therapy, Faculty of Rehabilitation, International University of Health and Welfare, Okawa, Fukuoka, Japan
Y.E. Huh1 , J.-S. Kim1 , S.-H. Park1 1 Department of Neurology, Seoul National University Bundang Hospital, Korea
Objective: Event-related potentials (ERPs) were recorded to explore neural responses to unconscious face processing. Methods: Faces (neutral or fearful) or objects were presented under subthreshold (invisible), threshold, and supra-threshold (visible) conditions followed by a 1,000-ms mask stimulus. We recorded ERP responses at Oz, T5, T6, Cz, and Pz. To determine the effect of face visibility on ERPs, exposure durations of approximately 20, 30 and 300 ms were used. We inverted stimuli to examine the effects of physical stimulus features.
Objective: Horizontal head shaking at 2 to 3 Hz for 10 to 20 seconds can induce nystagmus in patients with central as well as peripheral vestibular dysfunction. In contrast to head shaking nystagmus (HSN) in peripheral vestibulopathies, little is known of the patterns and mechanisms of HSN in central vestibular disorders. The aim of this study was to determine the mechanism of HSN in circumscribed cerebellar lesions. Methods: We analyzed the patterns of HSN in 47 patients with unilateral infarction in the territory of the posterior inferior cerebellar artery (PICA). We also measured gain, time constant (TC), and tilt suppression of the vestibulo-ocular reflex (VOR), and compared those parameters among the groups after dividing the patients into three groups, without HSN, with HSN but without perverted response, and with perverted HSN. Results: HSN was observed in 25 (53.2%) patients. Twelve (25.5%) of them exhibited perverted downbeat HSN. Compared with normal controls, the
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Objective: It is assumed that the processing of facial expression and facial identity are independent each other. However, in recent psychological studies with a modified selective attention task, there is asymmetric dependency between these processes, and it is shown that facial identity influences facial expression recognition. The purpose of this study was to examine the effect of facial identity on facial expression recognition by recording event-related potentials (ERPs) with a modified selective attention task. Methods: Twenty normal adults participated in this study. Two male faces with angry or happy expressions were presented for 500 ms. Participants were asked to make a rapid judgment of these facial expressions under two different identity conditions. The baseline condition stipulated that participants judged facial expressions while the identity was held constant. As the filtering condition, participants judged facial expressions while the identity was varied randomly. ERPs were recorded by 128 electrodes during the presentation of the expressions. Results: We focused on the N170 component which is related to the structural encoding of faces and not modulated by emotional expressions in many studies. Topographical maps of grand averaged ERPs revealed that the N170 was recorded in a time window between 120 and 190 ms in the lateral occipito-temporal area. The N170 amplitude was significantly larger for angry faces than for happy faces, and larger under the baseline condition than under the filtering condition. Also the N170 latency was significantly longer under the baseline condition than under the filtering condition. Conclusions: These results suggest that the N170 is modulated by facial expressions and the identity condition. Therefore, we conclude that facial identity influences ERPs during facial expression recognition.
Posters Results: The amplitude of the occipital P1 (120 ms) and N1 (160 ms) for subthreshold faces was significantly different from those for objects. Specifically, the P1 amplitude elicited by upright faces was significantly larger than for inverted faces. The occipital N1 amplitude for faces was smaller than for objects. In contrast, the amplitude of the occipitotemporal N170 for faces but not for objects was significantly greater in the threshold and supra-threshold conditions. Conclusions: Our results suggest that the P1 and N1 have differential effects on early-stage unconscious face recognition, whereas the N170 reflects conscious face recognition. Significance: Even subthreshold faces were processed unconsciously at an early visual stage, suggesting a sequential pathway of information processing that proceeds to facespecific processing mechanisms. P1-16 An electrophysiological investigation of the emotional influence on the breadth of attention at early sensory processing stages H. Moriya1,2 , T. Kasai3 , H. Nittono1 Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan, 2 Graduate School of Education, Hokkaido University, Hokkaido, Japan, 3 Faculty of Education, Hokkaido University, Hokkaido, Japan 1
Objective: It has been suggested that emotional states modulate the breadth of attentional focus. However, it remains unclear which processing stage is responsible for this effect. Evidence from research using event-related brain potentials (ERPs) suggests that the P1 component evoked by attended visual stimuli reflects the focus of attention at early sensory processing stages. In this study, we recorded ERPs to examine whether emotional states influence the breadth of attentional focus at early stages. Methods: Twelve university students participated in the experiment. To induce negative, neutral, and positive emotional states, participants viewed affective pictures before a selective attention task. In the selective attention task, two letter pairs were presented in the left and right visual fields. In most trials, unmatched letter pairs (e.g., TL) were presented in both visual fields (standard stimuli, p = 0.80). In the other trials, a matched letter pair (e.g., SS) was presented at either the left or right visual field (target stimuli; p = 0.10, respectively). After viewing affective pictures, participants directed their attention to the left or right visual field and detected a target stimuli presented at the attended visual field. ERPs were recorded from 25 scalp electrodes. Results: Subjective ratings indicated that the presentation of affective pictures induced negative and positive emotional states. The P1 evoked by standard stimuli at occipitotemporal sites was more positive over the hemisphere contralateral to the attended visual hemifield. This contralateral preponderance effect has been assumed to reflect the attentional gain control mechanism of the visual cortices. However, this P1 attention effect did not differ between the negative, neutral, and positive emotional conditions. Conclusions: The results suggest that emotional states do not modulate the breadth of attentional focus at early visual processing stages, at least when the direction of attention is specified by instructions.
P1-15 Face-sensitive neural responses in the occipital cortex without visual awareness
P1-17 Mechanism of head shaking nystagmus from focal cerebellar lesions: flocculonodular dysfunction
T. Mistudo1 , Y. Kamio2 , Y. Goto3 , T. Nakashima1 , S. Tobimatsu1 1 Department of Clinical Neurophysiology, Neurological Institute, Faculty of Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan, 2 Department of Child and Adolescent Mental Health, National Institute of Mental Health, National Center of Neurology and Psychiatry, Kodaira, Japan, 3 Department of Occupational Therapy, Faculty of Rehabilitation, International University of Health and Welfare, Okawa, Fukuoka, Japan
Y.E. Huh1 , J.-S. Kim1 , S.-H. Park1 1 Department of Neurology, Seoul National University Bundang Hospital, Korea
Objective: Event-related potentials (ERPs) were recorded to explore neural responses to unconscious face processing. Methods: Faces (neutral or fearful) or objects were presented under subthreshold (invisible), threshold, and supra-threshold (visible) conditions followed by a 1,000-ms mask stimulus. We recorded ERP responses at Oz, T5, T6, Cz, and Pz. To determine the effect of face visibility on ERPs, exposure durations of approximately 20, 30 and 300 ms were used. We inverted stimuli to examine the effects of physical stimulus features.
Objective: Horizontal head shaking at 2 to 3 Hz for 10 to 20 seconds can induce nystagmus in patients with central as well as peripheral vestibular dysfunction. In contrast to head shaking nystagmus (HSN) in peripheral vestibulopathies, little is known of the patterns and mechanisms of HSN in central vestibular disorders. The aim of this study was to determine the mechanism of HSN in circumscribed cerebellar lesions. Methods: We analyzed the patterns of HSN in 47 patients with unilateral infarction in the territory of the posterior inferior cerebellar artery (PICA). We also measured gain, time constant (TC), and tilt suppression of the vestibulo-ocular reflex (VOR), and compared those parameters among the groups after dividing the patients into three groups, without HSN, with HSN but without perverted response, and with perverted HSN. Results: HSN was observed in 25 (53.2%) patients. Twelve (25.5%) of them exhibited perverted downbeat HSN. Compared with normal controls, the