Shu Omoto

P1 and P2 components of human visual evoked potentials are modulated by depth perception of 3-dimensional images

OBJECTIVE To determine the cerebral activity correlated with depth perception of 3-dimensional (3D) images, by recording of human visual evoked potentials (VEPs). METHODS Two figures consisting of smaller and larger squares were presented alternately. VEPs were recorded in two conditions. In condition I, we used two figures which yielded flat 2-dimensional images. In condition II, we used two figures which yielded 3D images, which were concave and convex, respectively. RESULTS P1, P2, and N1/P2 amplitude were significantly greater in condition II than in condition I. The P1/N1 amplitude tended to be greater in condition II than in condition I. P1 and N1 were predominantly distributed over the right temporo-parieto-occipital regions. P2 and N2 were distributed over bilateral parieto-occipital regions. CONCLUSIONS The difference in P1 amplitude between two conditions can be explained by the difference between conditions, one of which yielded depth perception while the other did not, since previous studies showed that P1 and N1 are modulated by perception of images in depth. The role of P2 and the mechanism responsible for the increase in P2 amplitude during condition II remain unknown. SIGNIFICANCE We recorded VEPs and identified electrophysiological correlates of depth perception with 3D images produced by concave/convex figures.

Early sensory information processes are enhanced on visual oddball and S1–S2 tasks in Parkinson's disease: a visual event-related potentials study

To observe sensory and cognitive information processing in Parkinsons disease (PD), 34 PD patients and 26 controls were investigated. A visual oddball paradigm and an S1-S2 paradigm were employed to record the early (P1, N1, P2) and late (N2, P3) event-related potentials (ERPs) at Cz, Pz and Oz. Results showed: (1) enlarged P1 amplitude at all electrode locations on both tasks, (2) shortened N1 latency and enlarged P2 amplitude at Oz on both tasks, (3) enlarged N1 amplitude at Cz during an oddball paradigm, (4) delayed N2 latency and decreased N2, P3 amplitude on both tasks, and (5) delayed P3 latency and reaction time during the S1-S2 paradigm. Abnormal ERP changes were correlated with worsened scores on Wechsler Adult Intelligence Scale-Revised and motor dysfunction scales in PD. We surmise overactive aspects or failed inhibitory modulation of sensory information processing in the early ERP stage and deficient cognitive information processing during the late ERP stage in PD.

Visual evoked potential changes related to illusory perception in normal human subjects

To study the human brain activity correlated with illusory perception, we chose a physically flat plane figure which looks like a convex figure. We studied visual evoked potential (VEP) changes, which reflect perceptual properties of illusory perception. We defined two paradigms, an illusory paradigm (IP) and a control paradigm (CP). Two stimuli, A and B, were randomly presented in the IP, while stimuli C and D were randomly presented in the CP. Stimulus A was the only figure which looked like a convex figure. A three-way analysis of variance was applied to the VEP components in each paradigm, with three factors: figures, electrodes, and sessions. Different configuration patterns between the two paradigms explained different grand mean VEP waveforms between the two paradigms; a greater N1 for the CP, a greater P1 for the IP, and marked attenuation of the N3 and P3 components for the IP. Significant main effects of figures only for the IP were found on P1 and P1N2 amplitude and P2 latency, which are assumed to reflect perceptual properties of stereoscopical illusory perception.

Modulation of event-related potentials in normal human subjects by visual divided attention to spatial and color factors

We investigated how visual event-related potentials (ERPs) are modulated by visual divided attention using an S1-S2 paradigm. Stimulus S2 consisted of non-target stimuli (Stimulus 1, 2, 3) and a target stimulus (Stimulus 4). The spatial/color factor was compared between S1 and S2: same/same (Stimulus 1); same/different (Stimulus 2); different/same (Stimulus 3); and different/different (Stimulus 4). The P1/N1 (90 approximately 150 ms) showed significantly greater amplitude in Stimulus 3 than in Stimuli 1 and 2. The N2 (230 approximately 290ms) showed significantly greater amplitude in Stimulus 2 than in Stimuli 1 and 3. We assumed that the P1/N1 was related to spatial attention, enhanced by alterations to the spatial factor, and that the N2 was related to color attention, enhanced by alterations to the color factor.

The hemispherical laterality of the visual evoked potentials during simple dot stimulus in normal human subjects

We studied scalp visual evoked potentials (VEPs) during a simple visual attention paradigm using a dot stimulus, which was presented every 1600 ms, at the center of a screen. The visual attention paradigm consisted of three tasks: task R, task L and task N. The subjects were instructed to press a button either with the right hand (task R) or with the left hand (task L) after seeing the dot. They were also instructed just to look at a dot, without pressing the button (task N). We defined N1 as a negative wave with a latency of 50-130 ms, P1 as a positive wave with a latency of 110-150 ms and N2 as a negative wave with a latency of 130-210 ms. During task R, P1-N2 amplitude at T6 was significantly greater than that at T5. The N1-P1 and N2 amplitudes at O2 were significantly greater than those at O1. During task L, the waveforms at T6 and O2 were more clearly detected than those at T5 and O1. We conclude that there is a functional dominance of the right cerebral hemisphere in our simple visual reaction tasks.

Modulation of Human Visual Evoked Potentials in 3-Dimensional Perception After Stimuli Produced With an Integral Imaging Method:

We investigated the neurophysiological correlates of stereoscopic 3-dimensional (3-D) depth perception by studying human visual evoked potentials (VEPs) with an integral imaging method characterized by horizontal but not vertical disparity. The VEPs were recorded in 10 healthy men under 4 conditions. In condition I, stimuli A (flat, 2-dimensional [2-D] image) and B (concave 3-D image) were presented at random. In condition II, stimuli A and C (convex 3-D image) were presented at random. In condition III, stimuli B and C were presented at random. In condition IV, stimuli A, B, and C were presented at random. The data for flat VEPs to stimulus A were combined in conditions I and II. The data for concave VEPs to stimulus B were combined in conditions I and III. The data for convex VEPs to stimulus C were combined in conditions II and III. When 2-way analysis of variance (ANOVA) for 2 factors, stimulus conditions (flat VEPs, concave VEPs, and convex VEPs) and electrode positions, was applied for VEP data, the N1 and N2 peak amplitudes differed significantly among the 3 stimulus conditions. In condition IV, the N1 peak amplitudes differed significantly among the 3 stimuli. Multiple comparisons followed by Bonferroni adjustment did not detect differences in the N1 peak amplitude between stimuli A and B, between stimuli A and C, or between stimuli B and C. We concluded that VEPs to concave or convex 3-D stimuli were significantly different from VEPs to flat 2-D stimuli. This is the first report showing modulation of human VEPs in 3-D perception with an integral imaging method.

The effect of attended color on the P1/N1 component of visual event-related potentials

Ten subjects were asked to pay attention to green or to red, when each visual stimulus was presented as two small squares, one green and the other red. They were instructed to push a button with the right hand, when the attended color was on the right side, and to push a button with the left hand, when the attended color was on the left side. The P1/N1 peak-to-peak amplitudes of visual event-related potentials were significantly higher when subjects focused attention on green rather than on red. We assume that the attended color had the effect of modulating the P1/N1 components.

Relationships among impairment, disability, handicap, burden of care, economic expenses, event‐related potentials and regional cerebral blood flow in Parkinson's disease

Background:  Relationships between impairment, disability and handicap in neurological diseases such as stroke and spinal cord injury have been studied using the framework of the international classification of impairment, disability and handicap, defined by World Health Organization. Those relationships in Parkinsons disease have rarely been studied on a statistical basis.

P1-1 Statistical analysis of VEPs to transient full-field pattern-reversal stimulation in 167 normal adults

Objective: To study the effect of age, gender, head size on patternreversal VEP. Method: Studies were conducted on 167 healthy adult volunteers (96 women, 71 men). The entire stimulating field subtended an angle of 16 degrees; each individual square of the checkerboard subtended 15, 30, or 60 minutes of arc measured to the eye. The subject was seated on a chair 127 cm from TV screen. Screen luminance was 25 luxes; background luminance was 15 luxes. VEPs were obtained by a stimulation frequency of a pattern reversal every 1 sec. Each evoked potential was the result of the summation of 60 responses. Midoccipital electrode was placed 5 cm above the inion, and was referred to a midfrontal reference electrode 12 cm above the nasion. We measured each peak latency of P50, N75, P100, and N145, and peak-to-peak amplitude of P50-N75, N75-P100, and P100-N145. Three way ANOVA was used to evaluate the effects of age, gender, head size on pattern-reversal VEP latency and amplitudes. Result: The age influenced each peaks latency. The checksize influenced each peak latency and amplitude (P50-N75, N75-P100). The smaller the checksize was, the larger both the latency and amplitude were. The gender each peak latency and each peak-to-peak amplitude. Latency was shorter and amplitude was larger in women than in men. The head size did not influence VEPs. Conclusion: Pattern VEP latencies are influenced by age, gender, and checksize. Pattern VEP amplitudes are influenced by gender and checksize. are influenced by gender and checksize.