In 2003 a patient known as TN lost his sight after suffering two successive strokes; the visual cortex in his brain was damaged and his vision was totally gone, although the eyes themselves were still healthy. During one examination years after he lost his sight, researchers were flabbergasted to see TN carefully navigate a hallway full of overturned chairs, scattered boxes and other obstacles without colliding with a single thing. How was this possible for a person who was completely blind?

The human mind is capable of many remarkable feats. In this issue, scientists reveal what the latest research says about cognition and how we can improve our mental health. Plus, read up on some of the cutting-edge findings in neuroscience.

In the case of TN, his doctors and other researchers characterized his condition as “blindsight” and discovered that the brain can act on signals received by the retina even if the person is not aware of what he or she is seeing. Indeed, the mind perceives and processes information with or without our awareness. Readings from functional MRI scans show that the brain makes decisions even before we are aware we have made them. Consciousness can exist, but it can evade detection in vegetative patients. New research reveals that a small percentage of comatose patients are in fact fully aware.

How can we boost brain health? Three types of meditation help to achieve focus with less effort, reduce anxiety and improve sleep. An active social life and the Mediterranean diet are two of a handful of tactics that may help ward off Alzheimer's disease. Some brain-training programs could also prevent dementia. We all know there is nothing like a good night's sleep—sack time enhances mood, memory, immune function and hormonal balance—and yet the scientific underpinnings for sleep continue to be a mystery.

As Rafael Yuste and George M. Church note, a century of research on the brain has only inched us toward complete understanding of this most crucial human organ. New technologies using DNA and optogenetics are certainly pushing us closer, but the enigmatic human mind may remain biology's final frontier for years to come.