Jon HamiltonJon Hamilton is a correspondent for NPR's Science Desk.
These PET scans show the normal distribution of opioid receptors in the human brain. A new study suggests ketamine may activate these receptors, raising concern it could be addictive.
Philippe Psaila/Science Source
Having more than one child is associated with a lower risk of Alzheimer's, research finds, as is starting menstruation earlier in life than average and menopause later.
Ronnie Kaufman/Blend Images/Getty Images
Several circular herpes virus particles are seen near a cell membrane. Roseola herpes virus causes a childhood illness marked by skin rashes and now has been found in brains with Alzheimer's disease.
Marines based in Okinawa, Japan, fire an M136 AT-4 rocket launcher as part of a weapons training exercise on the Kaneohe Bay Range Training Facility, in 2014.
Lance Cpl. Matthew Bragg/U.S. Marines/DVIDS
U.S. Marines fire the Carl Gustav rocket system during live-fire training last October. With each firing, the shooter's brain is exposed to pulses of high pressure air emanating from the explosion that travel faster than the speed of sound.
Sgt. Aaron Patterson/3rd Marine Division/DVIDS
Scientists placed two clusters of cultured forebrain cells side by side (each cluster the size of a head of a pin) in the lab. Within days, the minibrains had fused and particular neurons (in green) migrated from the left side to the right side, as groups of cells do in a real brain.
Courtesy of Pasca lab/Stanford University