Keiko Momose

Correlation between frequency doubling technology perimetry and temporal frequency characteristics in early glaucoma

To assess the effectiveness of the temporal frequency characteristics (TFC) as an indicator of visual damage in patients with early open-angle glaucoma, TFC obtained from VEPs elicited by a pseudorandom binary sequence (PRBS) stimulus was compared with the frequency doubling technology (FDT) thresholds. Cross power spectrum between the PRBS stimulus as the input and the PRBS-VEPs as the output was calculated, and was used as the TFC. The normalized amplitude of the TFC at 2–4, 6–8, 10–12, 14–16, 18–20, 22–24, 26–28, and 30–32 Hz was calculated, and a coefficient of correlation between these values and the FDT thresholds was determined. The coefficients of correlation between the FDT thresholds and the TFC at 18–20 Hz for the central, 10°, 20°, and 30° were r = 0.03,0.31,0.21, and 0.16, respectively in non-glaucomatous normal control eyes, and those for the same regions of eyes with early glaucoma were r = 0.66, 0.46, 0.38, and 0.35, respectively. The coefficients of correlation between the FDT thresholds and TFC at temporal frequencies were relatively high at 18–20 and 26–32 Hz. The time required to obtain the PRBS-VEP data was approximately the same as that for the FDT thresholds. The strong correlation between the two tests indicates that the FDT values and the high temporal frequency segments of the TFC may be useful as a preliminary indicator of visual damage in patients with early open-angle glaucoma. In addition, the strong correlation suggests that there was a preferential damage to the magnocellular system in glaucomatous eyes.

Embodied intersubjective engagement in mother-infant tactile communication: a cross-cultural study of Japanese and Scottish mother-infant behaviors during infant pick-up.

This study examines the early development of cultural differences in a simple, embodied, and intersubjective engagement between mothers putting down, picking up, and carrying their infants between Japan and Scotland. Eleven Japanese and ten Scottish mothers with their 6- and then 9-month-old infants participated. Video and motion analyses were employed to measure motor patterns of the mothers’ approach to their infants, as well as their infants’ collaborative responses during put-down, pick-up, and carry phases. Japanese and Scottish mothers approached their infants with different styles and their infants responded differently to the short duration of separation during the trial. A greeting-like behavior of the arms and hands was prevalent in the Scottish mothers’ approach, but not in the Japanese mothers’ approach. Japanese mothers typically kneeled before making the final reach to pick-up their children, giving a closer, apparently gentler final approach of the torso than Scottish mothers, who bent at the waist with larger movements of the torso. Measures of the gap closure between the mothers’ hands to their infants’ heads revealed variably longer duration and distance gap closures with greater velocity by the Scottish mothers than by the Japanese mothers. Further, the sequence of Japanese mothers’ body actions on approach, contact, pick-up, and hold was more coordinated at 6 months than at 9 months. Scottish mothers were generally more variable on approach. Measures of infant participation and expressivity indicate more active participation in the negotiation during the separation and pick-up phases by Scottish infants. Thus, this paper demonstrates a culturally different onset of development of joint attention in pick-up. These differences reflect cultures of everyday interaction.

Determination of the Chromatic Contrast Responses using Wavelet Analysis of Visual Evoked Potentials

In order to test the human color vision objectively, we have developed the technique using the sweep parameter VEP technique (Norcia and Tyler, 1985) with an iso-luminant chromatic grating is effective to detect the defective color vision (Momose and Saito, EMBC2002). In this study, the wavelet transform using complex Morlet wavelet was examined to detect the dynamical spectrum of VEP in color vision defectives. Vertical sinusoidal iso-luminant chromatic gratings (6 Hz, 2 c/deg) presented on a color monitor were used as stimuli. The two colors for the gratings were selected from the colors on the dichromatic iso-chromatic lines. Steady-state VEPs were recorded during a continuous decrease of chromatic contrast at 10%/s. VEP components at 12 Hz and 16 Hz were evaluated as the response signal and background EEG (noise), respectively. For deuteranopic iso-chromatic colors, the signal to noise ratio (SNR) of deuteranope and deteranomalia were significantly lower than those of normals (P<0.01), indicating that this technique is effective for objectively detecting of the color vision defectives

PRBS-determined temporal frequency characteristics of VEP in glaucoma

The purpose of this study was to determine whether the PRBS-VEP-determined temporal frequency characteristics (TFCs) of the visual pathways are useful for evaluating the properties of the visual system of glaucomatous patients. The VEPs elicited by pseudorandom stimulation (PRBS) with red LEDs were recorded from 26 eyes with primary open angle glaucoma and 11 age-matched normal eyes. The glaucomatous patients were divided into 3 groups according to the size and shape of their visual field defect; early (9), moderate (9), and severe (8). The cross-spectrum between the PRBS and PRBS-VEPs was used as the TFCs. The TFC of each glaucomatous group were compared to those of the normal controls. A depression of the TFC was found for the middle and high frequencies (18–28 Hz) in the moderate group, and the depression spread to lower frequencies (4–16 Hz) in the severe groups. The TFC values at 14–20 Hz were depressed in the moderate group and most frequencies were depressed significantly with the progression of glaucoma (p< 0.05). The sensitivity of the TFC at 18–20 Hz was 56%, 89% and 100% in the early, moderate and severe glaucoma groups, respectively, and the specificity was 82%. We conclude that the PRBS-determined TFC is altered in glaucomatous eyes, and the frequencies depressed were related to the degree of glaucoma. These findings indicate that the PRBS-determined TFC can be useful for evaluating visual function of glaucomatous eyes.

Characteristics of first and second order kernels of visually evoked potentials elicited by pseudorandom stimulation.

The characteristics of the first and the second order kernels of the visually evoked potentials (VEPs) elicited by pseudorandom binary sequence (PRBS) stimuli were investigated. VEPs were recorded from six eyes of four normal volunteers. The effects of stimulus luminance on the latency and amplitude of the first and the second order kernels were determined. The temporal interactions of transient VEPs elicited by single and double pulse stimuli were compared with the first and the second order kernels of the PRBS-VEPs. The correlation coefficient between the logarithm of the stimuli luminance (log I) and VEP amplitude of the first order kernels was 0.45 (p < 0.05), and that between log I and P1 latency was −0.62(p < 0.005). The second order kernels were not equal to the temporal interactions of the responses. However, the latency of the negative peak of the fourth slice was similar to the temporal interaction to double pulse stimulation with an inter-stimulus interval of 40 ms. An inhibitory component at 40 ms following the first stimulus was detected in the analysis of both PRBS-VEPs second order kernel and transient VEPs. This function may help to increase the frequency of critical flicker fusion in normal subjects.

Determination of the chromatic contrast sensitivity using sweep VEP technique

In order to develop a practical and rapid method to measure the chromatic contrast sensitivity function (CCSF), the sweet parameter technique (Norcia and Tyler, 1985) with an iso-luminant chromatic grating was investigated to determine whether this method can be applied to both normal subjects and subjects with defective color vision. Vertical sinusoidal isoluminant chromatic gratings presented on a color monitor were used as stimuli. The two colors for the gratings were selected from the colors on the dichromatic iso-chromatic lines. Steady-state VFPs were recorded during a continuous decrease of chromatic contrast at 10%/s. The amplitudes of the VEP component at twice of the temporal frequency of the stimulus were evaluated. VEPs elicited by 6, 8, and 10 Hz temporal frequencies, and 0.5, 1, and 2 c/deg spatial frequencies were recorded. For all stimulus conditions, the VEP amplitudes reproducibly decreased with a decrease of chromatic contrast. The modified sweep parameter technique resulted in large amplitudes and reproducible CCSF curves which should be effective for measuring defective color vision.

A study of color responses in visual evoked potentials using the kernel method

The relationship between color stimuli and VEPs was considered. VEPs elicited from normal subjects by chromatic modulated stimuli were measured, and their binary kernels were estimated by a nonlinear system identification method. Results showed that first-order binary kernels depended on the color of the stimulus. Opponent-color responses were considered to be included in first-order binary kernels.

Effects of Task Difficulty and Training of Visuospatial Working Memory Task on Brain Activity

Visuospatial working memory is one of the important cognitive processes and makes it possible to maintain and manipulate the visual information stored in brain systems. In this study, effects of task difficulty and two-week training of visuospatial working memory task on brain activity and its neural mechanisms were investigated.

Measurement of color discrimination threshold using visually evoked potential and its correlation with psychophysical measure

Purpose was to determine whether our developed electrophysiological technique (Momose and Saito, 2002) using visually evoked potential (VEP) is effective for determining the color discrimination threshold in human. Both VEP and psychophysical color matching measurement were applied to three normal volunteers, and their correlation and sensitivity were investigated. Colors on the MacAdam ellipse were selected for stimulus. Threshold determined by VEP was well correlated with psychophysical measure (r = 0.88 and 0.75 in two subjects), and was about 24 times higher than psychophysical ones. VEP measurement was done within much shorter time (30 min.) than psychophysical method (3 hours). VEP determined color discrimination threshold can be effective for the human color vision testing.

Nonlinear characteristics of visual evoked potential and their correlation with the visual responses on magnocellular and parvocellular pathways

Purpose was to investigate the nonlinear characteristics of visual evoked potentials (VEPs), and their correlation with the visual responses on parvocellular and magnocellular pathways. The VEPs elicited by checkerboard pattern alternating based on pseudorandom binary sequence were measured, and their nonlinear parameters (binary kernels) were calculated. VEPs to checkerboard with 0.5, 1.0, 2.0 and 4.0 [c/d] were measured. First and second-order binary kernels were compared with steadystate VEPs (S-VEPs) to pattern reversal stimulation with a constant temporal frequency (4, 8, 12, 16, and 32 Hz). Positive peak latency at 150 ms of second-order first slice was correlated with S-VEP amplitude for 32 Hz (r = - 0.71). Amplitudes of second slice were well correlated with S-VEPs to 4, 8, 12, and 16 Hz stimuli (r = 0.62, 0.77, 0.61, and 0.72). These results support the previously reported observations that the first and second slice response functions reflect the response of the parvocellular and magnocellular pathways, respectively.