Evidence suggests that it really affects what psychiatrists like me call sustained engagement — an important difference in understanding how to think about the condition.

Scientists are developing imaging techniques and blood tests that one day may enable doctors to identify the disease definitively in living patients.

© Danny Karnik/Associated Press

The animals may help reveal the causes of brain disease in people and point the way to treatments. But researchers already are calling for new ethical guidelines.

Experts say that after childbirth, intrusive thoughts are common and mostly benign. Lindsay Clancy’s story provides a disturbing exception.

© Pool photo by Greg Derr

Models of the insect’s nervous system have been trained to solve a Rubik’s Cube, play video games and even parallel park a car.

Models of the insect’s nervous system have been trained to solve a Rubik’s Cube, play video games and even parallel park a car.

They are moving too fast for the normal mind to keep up, but elite drivers have more densely packed brain cells where it counts and use their minds more efficiently.

Given access to email, A.I. agents have started reaching out to the philosophers and researchers exploring deep questions about them.

© Benjamin Rasmussen for The New York Times