FIGURE 2.

Estimated cortical sources of nap delta activity. Grand average current density maps for the estimated sources of delta activity during the first 60 min of N2/N3 sleep are shown for young adults (top row) and older adults (middle row). The results of the vertex-wise permutation test comparing estimated sources of delta activity between young and older adults are shown as the test statistic (t) map (bottom row), masked using α = 0.025 to reflect the two-tailed nature of the underlying t-tests.