1,721,049 research outputs found
Event-related potentials study on cross-modal discrimination of Chinese characters
No full textEvent-related potentials (ERPs) were measured in 15 normal young subjects (18-22 years old) using the "cross-modal and delayed response" paradigm, which is able to improve inattention purity. The stimuli consisted of written and spoken single Chinese characters. The presentation probability of standard stimuli was 82.5% and that of deviant stimuli was 17.5%. The attention components were obtained by subtracting the ERPs of inattention condition from those of attention condition. The results of the N1 scalp distribution demonstrated a cross-modal difference. This result is in contrast to studies with non-verbal as well as with English verbal stimuli. This probably reflected the brain mechanism feature of Chinese language processing. The processing location of attention was varied along with verbal/ non-verbal stimuli, auditory/visual modalities and standard/deviant stimuli, and thus it has plasticity. The early attention effects occurred before the exogenous components, and thus provided evidence supporting the early selective theory of attention. According to the relationship of N1 and Nd1, the present result supported the viewpoint that the N1 enhancement was caused by endogenous components overlapping with exogenous one rather than by pure exogenous component.Event-related potentials (ERPs) were measured in 15 normal young subjects (18-22 years old) using the "cross-modal and delayed response" paradigm, which is able to improve inattention purity. The stimuli consisted of written and spoken single Chinese characters. The presentation probability of standard stimuli was 82.5% and that of deviant stimuli was 17.5%. The attention components were obtained by subtracting the ERPs of inattention condition from those of attention condition. The results of the N1 scalp distribution demonstrated a cross-modal difference. This result is in contrast to studies with non-verbal as well as with English verbal stimuli. This probably reflected the brain mechanism feature of Chinese language processing. The processing location of attention was varied along with verbal/non-verbal stimuli, auditory/visual modalities and standard/deviant stimuli, and thus it has plasticity. The early attention effects occurred before the exogenous components, and thus provided evidence supporting the early selective theory of attention. According to the relationship of N1 and Nd1, the present result supported the viewpoint that the N1 enhancement was caused by endogenous components overlapping with exogenous one rather than by pure exogenous component
Susceptibility to motion sickness induced by optokinetic rotation and self-rotation by walking around a vertical pole
No full text31 subjects viewed an optokinetic rotating drum for 12 min, in one session and self-rotated by walking quickly around a vertical pole with eyes closed while alternately flexing and extending the neck in another session, The self-rotation session contained 6 trials (3 clockwise and 3 counterclockwise rotations), Each trial contained 20 cycles of self-rotations, Self-reported ratings of nausea and symptoms of motion sickness were obtained for each session. The subjects developed symptoms of nausea, sweating, dizziness, headache, drowsiness, and changes in salivation in both drum rotation and self-rotation sessions. However, the subjects reported higher ratings of nausea in the session of optokinetic rotation than in the session of self-rotation around a vertical pole. These results indicated that both optokinetic rotation and self-rotation with eyes closed while alternately flexing and extending the neck are effective means of inducing nausea and motion sickness.31 subjects viewed an optokinetic rotating drum for 12 min, in one session and self-rotated by walking quickly around a vertical pole with eyes closed while alternately flexing and extending the neck in another session, The self-rotation session contained 6 trials (3 clockwise and 3 counterclockwise rotations), Each trial contained 20 cycles of self-rotations, Self-reported ratings of nausea and symptoms of motion sickness were obtained for each session. The subjects developed symptoms of nausea, sweating, dizziness, headache, drowsiness, and changes in salivation in both drum rotation and self-rotation sessions. However, the subjects reported higher ratings of nausea in the session of optokinetic rotation than in the session of self-rotation around a vertical pole. These results indicated that both optokinetic rotation and self-rotation with eyes closed while alternately flexing and extending the neck are effective means of inducing nausea and motion sickness
Temporal course of emotional negativity bias: An ERP study
Full text linkThere is considerable evidence that people are especially sensitive to emotionally negative materials. However, the temporal course of the negativity bias is still unclear. To address this issue, we observed the changes of P2, late positive components (LPC) and lateralized readiness potential (LRP) under positive, negative and neutral conditions, with International Affective Picture System (IAPS) pictures as emotional stimuli. We found that the amplitude of P2 in the negative block was significantly larger than that in the positive block, indicating that the attentional negativity bias occurred very early in emotion perception. The LPC amplitude evoked by negative pictures was larger than that by positive and neutral pictures, suggesting that the negativity bias also occurred in a later evaluation stage of emotion processing. The response-locked LRP interval was shortest in the block of negative pictures, indicating that the negative contents elicited a reaction priming effect. Above all, this research showed that emotional negativity bias could occur in several temporal stages distinguished by attention, evaluation and reaction readiness periods.There is considerable evidence that people are especially sensitive to emotionally negative materials. However, the temporal course of the negativity bias is still unclear. To address this issue, we observed the changes of P2, late positive components (LPC) and lateralized readiness potential (LRP) under positive, negative and neutral conditions, with International Affective Picture System (IAPS) pictures as emotional stimuli. We found that the amplitude of P2 in the negative block was significantly larger than that in the positive block, indicating that the attentional negativity bias occurred very early in emotion perception. The LPC amplitude evoked by negative pictures was larger than that by positive and neutral pictures, suggesting that the negativity bias also occurred in a later evaluation stage of emotion processing. The response-locked LRP interval was shortest in the block of negative pictures, indicating that the negative contents elicited a reaction priming effect. Above all, this research showed that emotional negativity bias could occur in several temporal stages distinguished by attention, evaluation and reaction readiness periods. (C) 2005 Elsevier Ireland Ltd. All rights reserved
Cross-modal selective attention to visual and auditory stimuli modulates endogenous ERP components
No full textIn two experiments event-related potentials (ERPs) to visual and auditory stimuli were measured in 12 healthy subjects. A cross-modal and delayed response paradigm was used that allows ERPs to be obtained separately to attended and unattended stimuli under conditions in which unattended stimuli are less likely to be covertly or randomly attended. The results showed: (1) N1 enhancement with attention for standard stimuli in auditory and visual modalities and for deviant stimuli in the visual modality; (2) The onset time and scalp distribution of both the N1 for attend condition and Nd1 were similar regardless of standard or deviant stimuli in the auditory and visual modality; the onset time of Nd1 elicited by auditory and visual deviant stimuli was earlier than that of the unattended NI, and their scalp distributions were different; and (3) The Nd1 components elicited by auditory and visual deviant stimuli were distributed over the respective primary sensory areas, but Nd1 components evoked by auditory and visual standard stimuli were distributed over the frontal scalp. These results suggest that the attended N1 enhancement is primarily caused by a component with endogenous origins and that the early attention effect occurs before the exogenous components. The results support the view that the cross-modal attention to deviant stimuli modulates modality-specific processing in the brain, whereas attention to standard stimuli affects modality-nonspecific or supramodal brain systems.In two experiments event-related potentials (ERPs) to visual and auditory stimuli were measured in 12 healthy subjects. A cross-modal and delayed response paradigm was used that allows ERPs to be obtained separately to attended and unattended stimuli under conditions in which unattended stimuli are less likely to be covertly or randomly attended. The results showed: (1) N1 enhancement with attention for standard stimuli in auditory and visual modalities and for deviant stimuli in the visual modality; (2) The onset time and scalp distribution of both the N1 for attend condition and Nd1 were similar regardless of standard or deviant stimuli in the auditory and visual modality; the onset time of Nd1 elicited by auditory and visual deviant stimuli was earlier than that of the unattended NI, and their scalp distributions were different; and (3) The Nd1 components elicited by auditory and visual deviant stimuli were distributed over the respective primary sensory areas, but Nd1 components evoked by auditory and visual standard stimuli were distributed over the frontal scalp. These results suggest that the attended N1 enhancement is primarily caused by a component with endogenous origins and that the early attention effect occurs before the exogenous components. The results support the view that the cross-modal attention to deviant stimuli modulates modality-specific processing in the brain, whereas attention to standard stimuli affects modality-nonspecific or supramodal brain systems. (C) 1999 Elsevier Science B.V. All rights reserved
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