In Loving Memory of Samuel Bomgard
Effective dyslexia remediation specifically designed for older struggling readers (age 7+).

Estimation of the Timing of Human Visual Perception

by Kaoru Amano, Naokazu Goda, Shin'ya Nishida, Yoshimichi Ejima, Tsunehiro Takeda, and Yoshio Ohtani

To explore the timing and the underlying neural dynamics of visual perception, we analyzed the relationship between the manual reaction time (RT) to the onset of a visual stimulus and the time course of the evoked neural response simultaneously measured by magnetoencephalography (MEG). The visual stimuli were a transition from incoherent to coherent motion of random dots and an onset of a chromatic grating from a uniform field, which evoke neural responses in different cortical sites. For both stimuli, changes in median RT with changing stimulus strength (motion coherence or chromatic contrast) were accurately predicted, with a stimulus-independent postdetection delay, from the time that the temporally integrated MEG response crossed a threshold (integrator model). In comparison, the prediction of RT was less accurate from the peak MEG latency, or from the time that the nonintegrated MEG response crossed a threshold (level detector model). The integrator model could also account for, at least partially, intertrial changes in RT or in perception (hit/miss) to identical stimuli. Although we examined MEG—RT relationships mainly for data averaged over trials, the integrator model could show some correlations even for single-trial data. The model predictions deteriorated when only early visual responses presumably originating from the striate cortex were used as the input to the integrator model. Our results suggest that the perceptions for visual stimulus appearances are established in extrastriate areas [around MT (middle temporal visual area) for motion and around V4 (fourth visual area) for color] ?150—200 ms before subjects manually react to the stimulus.

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quote-sign Our Dynaread team members are required to hold themselves accountable for serving our clients in adherence with our core values...

Contribute with scientific and overall integrity.
Retain the focus on the needs of each individual child.

DYNAREAD: Grounded in Reality

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Dynaread has been developed in the trenches of actual remediation, with our feet firmly planted on the ground. Scientific research is essential (and we consistently use it), but we also understand the realities at home and in school. Not all homes have two parents, not all Dad's or Mom's are always home, there is oftentimes no money, schools lack staff or funding. We listen, we observe, we discuss, and we build the best solutions we can for older (ages 7+) struggling readers.

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