Pavlovian-based neurofeedback enhances meta-awareness of mind-wandering.

Absorption in mind-wandering (MW) may worsen our mood and can cause psychological disorders. Researchers indicate the possibility that meta-awareness of MW prevents these mal-effects and enhances favorable consequences of MW, such as boosting creativity; thus, meta-awareness has attracted psychological and clinical attention. However, few studies have investigated the nature of meta-awareness of MW, because there has been no method to isolate and operate this ability. Therefore, we propose a new approach to manipulate the ability of meta-awareness. We used Pavlovian conditioning, tying to it an occurrence of MW and a neutral tone sound inducing the meta-awareness of MW. To perform paired presentations of the unconditioned stimulus (neutral tone) and the conditioned stimulus (perception accompanying MW), we detected participants' natural occurrence of MW via electroencephalogram and a machine-learning estimation method. The double-blinded randomized controlled trial with 37 participants found that a single 20-min conditioning session significantly increased the meta-awareness of MW as assessed by behavioral and neuroscientific measures. The core protocol of the proposed method is real-time feedback on participants' neural information, and in that sense, we can refer to it as neurofeedback. However, there are some differences from typical neurofeedback protocols, and we discuss them in this paper. Our novel classical conditioning is expected to contribute to future research on the modulation effect of meta-awareness on MW.

Comparison of Japanese and Scottish Mother-Infant Intersubjectivity: Resonance of Timing, Anticipation, and Empathy During Feeding.

Feeding involves communication between mothers and infants and requires precise synchrony in a special triadic relationship with the food. It is deeply related to their intersubjectivity. This study compared the development of mother-infant intersubjectivity through interactional synchrony in feeding between 11 Japanese and 10 Scottish mother-infant dyads, observed at 6 and 9 months by video. Japanese mothers were more deliberate in feeding at an earlier age, whereas Scottish mothers were significantly more coercive than Japanese mothers at an earlier age. Japanese mothers brought the spoon to infants with a pause to adjust the timing of insertion to match their infants' readiness, whereas this pause was not observed in Scottish mothers. Isomorphic mouth opening between mothers and infants was observed. This empathic maternal display is an important element of intersubjectivity in infant feeding that differed between Scottish and Japanese mothers. Scottish mothers' mouth opening always followed their infants' mouth opening, but about half of Japanese mothers preceded their infants. Further, the mouths of Scottish infants and mothers opened almost at the same time as spoon insertion. In contrast, Japanese mothers' mouth opening did not co-occur with the insertion but was close to spoon arrival, a subtle but important difference that allows for greater infant autonomy. The time structure of Scottish mother-infant interactions was simpler and more predictable at 9 months than in Japan, where the structure was more variable, likely due to a stronger regulation by Scottish mothers. In conclusion, Scottish mother-infant intersubjectivity is characterized as more maternally reactive and mother-centered, whereas Japanese mother-infant intersubjectivity is characterized as more maternally empathetic and infant-centered. Cultural differences in intersubjectivity during feeding between Japan and Scotland are further discussed in relation to triadic relationships and parenting styles.

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.

Stochastic resonance with a mixture of sub-and supra-threshold stimuli in a population of neuron models.

This paper presents a novel type of stochastic resonance (SR) with a mixture of sub- and supra-threshold stimuli in a population of neuron models beyond regular SR and Supra-threshold SR (SSR) phenomena. We investigate through computer simulations if the novel type of SR can be observed or not, using the mutual information (MI) estimated from a population of neural spike trains as an index of information transmission. Computer simulations showed that the MI had a typical type of SR curves, even when the balance between sub-and supra-threshold stimuli was varied, suggesting the novel type of SR. Moreover, the peak of MI increased as the balance of supra-threshold stimuli got stronger, i.e., as the situation was getting close to the SSR from the regular SR. This finding could accelerate our understanding about how fluctuations play a role in processing information carried by a mixture of sub-and supra-threshold stimuli.

Extraction of M and P components from the visual evoked potential using pseudorandom stimulation with swept parameter technique.

To develop a method of extract magnocellular (M) and parvocellular (P) components from VEP, the nonlinear system identification method using pseudorandom binary sequence (PRBS) stimulation combined with swept parameter technique was examined. VEP elicited by achromatic sinusoidal grating reverse based on PRBS was recorded and their binary kernels were calculated as cross-correlation between PRBS and VEP. To manipulate the magnitudes of M and P visual pathways responses in VEP, the spatial frequency of gratings were swept during the PRBS stimulation. VEP to this stimulation was recorded from 4 healthy participants and their binary kernels changes during the stimulation were evaluated. PRBS stimulation of 40950 ms period was repeated twice, and the spatial frequency was swept from 0.5 to 9 [c/d] or 9 to 0.5 [c/d] within the period. Binary kernel of each epoch was calculated by cross-correlating VEP with PRBS of 40950 ms duration. Different waveforms of binary kernels obtained from the former and latter half of the PRBS stimulation were confirmed, and the waveforms were continuously changed during the stimulation. The changes may reflect the M and P pathway contribution changes during the stimulation and depend on the spatial frequency sweeping. The suggested technique would be effective for studying and screening several eye and neurocognitive disorders which have been reported to relate with selective damage in M/P pathways.

Stochastic resonance can enhance information transmission of supra-threshold neural signals.

Stochastic resonance (SR) has been shown to improve detection of sub-threshold signals with additive uncor-related background noise, not only in a single hippocampal CA1 neuron model, but in a population of hippocampal CA1 neuron models (Array-Enhanced Stochastic Resonance; AESR). However, most of the information in the CNS is transmitted through supra-threshold signals and the effect of stochastic resonance in neurons on these signals is unknown. Therefore, we investigate through computer simulations whether information transmission of supra-threshold input signal can be improved by uncorrelated noise in a population of hippocampal CA1 neuron models by supra-threshold stochastic resonance (SSR). The mutual information was estimated as an index of information transmission via total and noise entropies from the inter-spike interval (ISI) histograms of the spike trains generated by gathering each of spike trains in a population of hippocampal CA1 neuron models at N = 1, 2, 4, 10, 20 and 50. It was shown that the mutual information was maximized at a specific amplitude of uncorrelated noise, i.e., a typical curve of SR was observed when the number of neurons was greater than 10 with SSR. However, SSR did not affect the information transfer with a small number of neurons. In conclusion, SSR may play an important role in processing information such as memory formation in a population of hippocampal neurons.

Simultaneous detection method of P300 event-related potentials and eye gaze point using multi-pseudorandom and flash stimulation for brain computer interface.

A method for simultaneous detecting of P300 response and eye gaze point using visual evoked potentials (VEPs) elicited by multi-pseudorandom and flash stimuli was examined. Prototype system which would be a practical brain computer interface is established and evaluated. Visual stimuli consisted of six small squares (visual angle of 0.7x0.7 deg) surrounded by frames/a frame (2x2 deg). Squares were flashed with an interval of 180 ms to elicit event-related potential of P300, and luminance of each frame was modulated, based on pseudorandom binary sequences (PRBS) of 10.23 seconds. Six visual stimuli were simultaneously presented on the monitor and subjects were instructed to focus attention successively on an appointed square and EEG was recorded during this task. The cross correlation functions (kernels) of EEGs and each PRBS were calculated and used to determine the subject gazed target. Clear P300 and kernel response for target were simultaneously detected, indicating that this technique could be useful as a practical brain computer interface system.

Influence of moving sight by turning over frequency.

In late years, f-MRI (functional magnetic resonance imaging) are used for analysis of a visual function. In case of the study for a visual function, the checker flag pattern consists of white square and black square is usually used for sight stimulation. In sight stimulation using this pattern, a color of square (black and white) changes alternately at constant frequency. It is usually called pattern reversal stimulation. When this pattern is used for stimulation, the subject sometimes feels movement for the shown stimulation pattern. We think that this sensation of movement relates to spatial frequency (that means the size of a square of a stimulation pattern) of a stimulation image and a turning over frequency of a stimulation pattern strongly. Our objectives of this study are the following. 1) Clarify a part of the brain that is a cause of this moving sensation. 2) Investigate the relationship among the magnitude of this sensation, spatial frequency and turning over frequency. Three normal adults were used for the subject. This time, turning over frequency was changed to 8 Hz by 1 Hz step under fixed spatial frequency. Under this condition, we examined the state of activation of a V1 area. In addition, we examined whether BOLD effect varied with a change of a stimulation color. In this experiment, we used blue and yellow color instead of black and white for stimulation, and the reaction was examined.

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

Purpose was to investigate the linear and nonlinear characteristics of VEPs, and their correlation with the visual parvocellular and magnocellular systems. The VEPs were elicited by pseudorandom luminance modulated stimulation from patients with primary open angle glaucoma and compared with normal subjects. VEPs were recorded from 26 eyes with primary open angle glaucoma (POAG) and 10 eyes of age-matched normal volunteers. To acquire the VEPs, the eye was stimulated with a pseudorandom binary sequence (PRBS) stimulus of 40 sec duration. The first (linear) and second-order (nonlinear) binary kernels were determined by a cross-correlation function between PRBS and VEP. The amplitudes of the first- and second-order kernels decreased with the advancement of POAG. Positive peak latencies around 120 ms of first slice of second-order kernels increased with the advancement of POAG, while the second slice amplitudes were not different in normal, early POAG and moderate POAG patients. These results support the observations in previous studies that the first and second slice response functions reflect the response of the M- and P-pathways, respectively.

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.

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.

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.

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 degrees, 20 degrees, and 30 degrees 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.

Visual evoked potentials elicited by pseudorandom stimulation from patients with macular degeneration.

PURPOSE: To investigate the effect of a central scotoma on the amplitude, implicit time (IT), and temporal frequency characteristics (TFC) of the visual evoked potentials (VEPs) elicited by a pseudorandom binary sequence (PRBS) stimulus in age-related macular degeneration (AMD) patients. METHODS: Twenty-six patients with AMD, 17 eyes with visual acuity of less than 20/100, and 9 eyes with visual acuity between 20/70 and 20/25, were examined. Nine eyes of age-matched healthy volunteers served as controls. To elicit the PRBS-VEPs, one eye was stimulated with a PRBS stimulus. The first-order kernel was calculated from a cross-correlation between the PRBS and the VEPs. The Fourier transformed first-order kernel was used as the TFC of the visual system. RESULTS: The mean IT of P2 (second positive peak) of the first-order kernel was significantly delayed (t-test, P <.05), and the P2-N2 (peak-to-peak of P2 and second negative peak N2) amplitude was significantly reduced (t-test, P <.01) in eyes with AMD. A depression of the TFC values in the 6-18 Hz band was prominent in patients with AMD (t-test, P <.01). CONCLUSION: PRBS-VEPs demonstrated a prolonged IT and reduced amplitude of the first-order kernel, and reduced TFC with a reduction of visual acuity in patients with macular degeneration.