Comparison of functional activation foci in children and adults using a common stereotactic space.

The development of methods allowing direct comparisons between child and adult neuroimaging data is an important prerequisite for studying the neural bases of cognitive development. Several issues arise when attempting to make such direct comparisons, including the comparability of anatomical localization of functional responses and the magnitude and time course of the hemodynamic responses themselves. Previous results suggest that, after transformation into a common stereotactic space, anatomical differences between children (ages 7 and 8) and adults are small relative to the resolution of fMRI data. Here, we investigate whether time courses (BOLD responses) and locations of functional activation foci show similarities as well. Event-related fMRI was performed on 16 children (ages 7 and 8) and 16 adults, who pressed buttons in response to a visual stimulus. After transforming images into Talairach space, the coordinates of four consistent activations in each hemisphere were determined for each subject: two foci in the sensorimotor cortex, one focus in the visual cortex, and one focus in the supplementary motor area (eight activations in total). In seven foci, time courses were similar between children and adults, and peak amplitudes of time courses were comparable in all eight foci. There were negligible between-group differences in location of all foci. Variability of activation location was statistically similar in the two groups. In voxelwise group comparison images, minimal differences were found between children and adults in visual and motor cortex regions. The small differences in time courses and locations of activation foci between child and adult brains validate the feasibility of direct statistical comparison of these groups within a common space.