Volume 10 Issue 12, December 2007

A new paper reports that dopaminergic neurons initially responded optimistically in rats given free choice between two rewards, as though the animal had chosen the better reward, even on trials when it failed to do so. These findings suggest that current computational theories of dopaminergic function may need to be revised.

Brain microglia increase their numbers in response to threats. Some of these cells were thought to enter the CNS from the blood, but two new studies suggest that experimental confounds could in part account for such results.

Maintaining a precise representation of sound frequency in auditory cortex is difficult because of converging diffuse thalamocortical inputs. A recent study demonstrates that this is accomplished via recurrent intracortical connections.

A recent study in Nature now shows that the main olfactory bulb contains a particular zone required for innate odor aversion, indicating that olfactory receptors have behavioral as well as chemical specificity.