Frontiers in Behavioral Neuroscience
In a stressful situation, rodents produce the stress hormone corticosterone. This helps the animal, because spatial learning is promoted when corticosterone binds to one of the stress hormone receptors (mineralocorticoid receptors) in the hippocampus, a region of the brain. Judith ter Horst and colleagues from Leiden University here show that female mice that lack the gene for the mineralocorticoid receptor in the forebrain have difficulty finding their way home through a maze, especially shortly before ovulation. The interaction between female sex hormones and stress hormones could result in worsening of spatial learning. There was also an interaction with stress: it was easier for mutant females to find their way home after they had been briefly and gently restrained, probably due to an increase in corticosterone levels in the blood. Ter Horst and colleagues conclude that mineralocorticoid receptors are necessary for efficient spatial learning by female mice.
Frontiers in Neuroscience
Abrupt changes in the patterns and complexity of anterior cingulate cortex activity
It simply feels good to regain your bearings after getting lost, especially when you are hungry and had been looking for a particular restaurant. Jeremy Seamans and colleagues from the University of British Columbia, Canada, here show that hungry rats experience a similar abrupt neural change when they stumble upon food in an unfamiliar environment. They recorded patterns of activity in the medial prefrontal cortex of the brain, an area implicated in the regulation of behavior and emotion. When the rats first realized that food had to begun to literally drop from above, their patterns of brain activity changed abruptly and dramatically from preceding patterns, characteristic of hungry rats that are busy exploring a new enclosure. Not only were the patterns completely different after finding the food, but they were also simpler. Seamans et al. conclude that whenever a critical goal is realized, the medial prefrontal cortex can change abruptly from a “search state”, where many outcomes are possible, to a simpler “consumption state” that needs to consider fewer outcomes: principally, the outcome of digging into tasty food.