To explain why some patients get an itch along with their pain relief when given morphine, researchers examined two variants of the morphine receptor and found they relay two signals—one that relieves pain and one that induces an itching sensation. The finding of distinct cellular pathways suggests a way to uncouple these effects.2. The hunger switch
Hormones that relay hunger or satiety trigger a feedback loop in the brain that continues long after the hormones are degraded, creating a memory of hunger that may influence the success of dieters.3. How blind fish keep time
Cavefish that live in complete darkness follow a clock that's 47 hours long, rather than the standard 24-hour clock entrained by normal daylight cycles. Interestingly, it appears that the fish use mutant versions of two light receptors found in zebra fish to regulate the remainder of the cavefish's peripheral clocks.4. Melding space and time
Not only do neurons in the brain's new-memory center fire at specific locations in order to relay information about location, but they also fire at particular intervals in order to record sequential events separated by time, bringing time and space information together.5. Stimulated mice stay leaner
Housing mice in environments with additional stimuli, such as a running wheel, not only increases their mental health, improving memory and conferring resistance to brain damage, but also helps them stay fitter, reducing the rate of diet-induced obesity.
(Read our 2009 feature on animal enrichment, “Lab Toys.”)6. A rewarding new path
Researchers find a new pathway in the brain that links a memory processing center with a reward center and is likely to be important in normal learning and addiction.7. Brain-immunity missing link
Researchers have long been puzzled as to how the nerves that feed into the spleen—an organ involved in immunity—could produce the acetylcholine signals that dampen inflammation, since spleenic cells don't make acetylcholine. New evidence points to a T-cell population in the spleen as the culprit, responding to nerve signals and producing acetylcholine.
(Read our news story "Neurotransmitter Regulated Immunity")http://f1000.com.