When a sunny disposition turns into an addiction
Despite health risks such as skin cancer, some people still have an instinctive desire to be in the sun. A study by researchers at Massachusetts General Hospital and Harvard Medical School suggests this could be due to an addiction to ultraviolet radiation, which causes the release of feel-good hormones called endorphins. The hormones act through the same pathway as heroin and related drugs.
Social behaviour tied to specific brain circuit
A team of Stanford University investigators has, for the first time, pinpointed a particular brain circuit to mammals' tendency to interact socially.
Stimulating this circuit increases a mouse's appetite for getting to know a strange mouse, while inhibiting it shuts down its drive to socialise with the stranger.
The findings, which appear in the journal Cell, enhance scientists' ability to understand how social behaviour operates - and how it can go wrong - in psychiatric disorders such as autism, schizophrenia and depression, says the study's senior author, Professor Karl Deisseroth.
Stress hormone linked to memory loss as we age
A short-term increase in cortisol - the hormone produced by the body during stressful periods - is critical for survival. It makes us more alert and able to think on our feet. But a new University of Iowa study reports a potential link between long-term exposure to the hormone and short-term memory loss in older adults. The study in the Journal of Neuroscience reveals that abnormally high or prolonged exposure to cortisol can cause the gradual loss of brain connections that help us process, store and recall information. This suggests that short-term memory decline in ageing adults may be slowed or prevented by treatments that decrease levels of cortisol in susceptible individuals.