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A common problem in brain imaging is how to most appropriately coregister anatomical and functional data sets into a common space. For surface-based recordings such as the event related optical signal (EROS), near-infrared spectroscopy (NIRS), event-related potentials (ERPs), and magnetoencephalography (MEG), alignment is typically done using either (1) a(More)
Neuroimaging data emphasize that older adults often show greater extent of brain activation than younger adults for similar objective levels of difficulty. A possible interpretation of this finding is that older adults need to recruit neuronal resources at lower loads than younger adults, leaving no resources for higher loads, and thus leading to(More)
The event-related optical signal (EROS) has been recently proposed as a method for studying noninvasively the time course of activity in localized cortical areas (G. Gratton and M. Fabiani, 1998, Psychonomic Bull. Rev. 5: 535-563). Previous data have shown that EROS has very good temporal resolution and can provide detailed surface activity maps. In the(More)
Brain aging is characterized by changes in both hemodynamic and neuronal responses, which may be influenced by the cardiorespiratory fitness of the individual. To investigate the relationship between neuronal and hemodynamic changes, we studied the brain activity elicited by visual stimulation (checkerboard reversals at different frequencies) in younger(More)
fMRI and ERP studies have shown that tasks comprising conflicting stimulus-response associations activate a variety of cortical regions. It remains unclear whether any of these areas are activated by all conflict tasks, or whether conflict resolution is a common property of a number of distinct anatomical regions. Several regions in frontal and parietal(More)
Sound repetition typically reduces auditory N1 amplitudes, more so at higher rates. This has been attributed to refractoriness of N1 generators. However, evidence that N1 attenuation is delayed 300-400 ms after the first occurrence of a repeated sound suggests an alternative process, such as inhibition, that requires 300-400 ms to become fully operational.(More)
PURPOSE To assess anomalous cortical organization of somatosensory function in a 23-year-old man who had had a neonatal infarct involving the left middle cerebral artery. MATERIALS AND METHODS The infarct destroyed the primary and secondary somatosensory areas of the subject's left hemisphere but caused only mild perturbation of somatosensation on the(More)
Transcranial magnetic stimulation (TMS) is a widely used experimental and clinical technique that directly induces activity in human cortex using magnetic fields. However, the neural mechanisms of TMS-induced activity are not well understood. Here, we introduce a novel method of imaging TMS-evoked activity using a non-invasive fast optical imaging tool, the(More)
Experimental glaucoma was produced in one eye of five cynomolgus monkeys with the argon laser delivering 100-200 50-mu spots at 1200-1500 mW power and 0.5 sec to 360 degrees of the mid-trabecular meshwork. Monocular electroretinograms (ERGs) were recorded prior to and 2, 3, and 4 mo following the laser treatment. In the laser-treated (glaucoma) eyes, normal(More)