Figure 2.

Population average BOLD time-series from V1. The average time-series data (expressed as percentage signal change) within the left V1 cortex for each subject was obtained for the 8-minute scan. The time-series from each subject was adjusted to remove a linear drift term and effects of no-interest (“spike” transients) and then averaged within groups. The three plots were set to have the same initial value at time zero. Stimulus timing is indicated by shades of gray and blue along the x-axis. The time-series from the right hemisphere shows qualitatively the same amplitude effect and persistence (data not shown).

BOLD: blood oxygen level-dependent.