Anhedonia - the inability to experience pleasure - is often found in people suffering from depression. Resarchers, from the Lawson Health Research Institute in Ontario studied 31 people, 16 of whom had recently been diagnosed with depression. They were asked to select their favourite music, then played it (along with a more neutral choisce for comparison purposes) while the levels of activity within their brains was monitored. The study found that the non-depressed participants had more neural activity in areas of the brain associated with reward processing and pleasre than the depressed participants.
You can find out more about this research at