The two faces of depression – two studies switch off symptoms in mice, but in opposite ways

In a lab at Stanford University, a mouse is showing signs of depression. For around 10 weeks, it has experienced a series of irritations, from bouts without food or water, to erratic sleep patterns. Now, its motivation is low—when picked up by the tail, it makes few attempts to escape, and it doesn’t try to explore new spaces. It’s also less willing to sip from a sugary liquid– a sign that it gets less pleasure from normally pleasurable activities. It is never easy to assess the mental health of an animal, but this mouse is clearly showing some of the classic symptoms of depression. But not for long. Earlier, Kay Tye and Julie Mirzabekov altered the mouse so that a flash of light can activate a small part of its brain—the ventral tegmental area (VTA), near the bottom of the brain and close to the midline. A burst of light, ...