Form and Function of Sleep Spindles across the Lifespan

Figure 2

Changes in spindle form across the lifespan. (a) Heat maps depict topographical spindle density during early development, adolescence, and aging. Spindles are initially seen over central areas of the brain and gradually develop over frontotemporal areas during the first year of life [11]. During adolescence, density reaches a relative maximum with equal distribution across frontal, central, and parietal leads. In aging, there is a return to the same pattern seen earlier in development, with highest density at central leads [12]. Below the heat maps are representations of spindle morphology at these ages. (b) Sleep spindle density (blue trace) increases throughout early development, peaking during puberty and steadily declining from adolescence to old age [13, 14]. Duration of sleep spindles (orange trace), on the other hand, peaks early in life, and then generally declines over the lifespan. Spindle amplitude (purple trace) is relatively small early in development, increasing to maximum values over the first year of life, and then steadily declines until old age [15]. (c) Neurodevelopmental milestones.