Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Traditionally, researchers have studied brain function in terms of physiological responses to environmental demands, yet much of the brain's energy is actually devoted to intrinsic neuronal signaling, or 'dark energy'. Zhang and Raichle describe the imaging strategies that are being used to explore intrinsic neuronal activity and examine the relationship between alterations in the functional architecture of intrinsic activity and neurological disease.