What influence does the variation in estrogen level have on the activation of the female brain? Using functional Magnetic Resonance Imaging, Jean-Claude Dreher, a researcher at the Cognitive Neuroscience Center (CNRS/UniversitÃ© Lyon 1), in collaboration with an American team from the National Institute of Mental Health (Bethesda, Maryland) directed by Karen Berman, has identified, for the first time, the neural networks involved in processing reward-related functions modulated by female gonadal steroid hormones. This result, which was published online on January 29, 2007 on the PNAS website, is an important step in better comprehension of certain psychiatric and neurological pathologies.
The human brain has a recompense system that predicts different types of reward (food, money, drugs...). The normal functioning of this system plays a fundamental role in many cognitive processes such as motivation and learning. This reward system, composed of dopaminergic neurons(1) situated in the mesencephalon (a very deep region of the brain) and their projection sites(2), is crucial for neural coding of rewards. Its dysfunction can result in disorders such as addictions and is also implicated in various psychiatric and neurological pathologies, such as Parkinson's disease and schizophrenic disorders. Many studies on animals prove that the dopaminergic(3) system is sensitive to gonadal steroid hormones (estrogen, progesterone). For example, female rats self-administer cocaine (a drug that acts on the dopamine system) in higher doses after estrogens have been administered to them. The influence of gonadal steroid hormones on the activation of the reward system remained to be studied in humans. A better knowledge of this influence should make for better understanding of the differences between men and women, particularly as observed in the prevalence of certain psychiatric pathologies and in vulnerability to drugs, (for which the dopaminergic system plays an important role.) It is known, for example, that the female response to cocaine is greater in the follicular phase of the menstrual cycle(4) than in the luteal phase(5). Moreover, schizophrenia tends to appear later in women than in men.
I'd appreciate it if someone could send me a PDF of the actual paper.
Why do predators and parasites eavesdropping on mating signals of their prey preferentially attack individuals producing certain types of call? Predators could use information encoded in calls to decide whom to attack.
Despite the icy cold and darkness, beneath the frozen surface of the sea in Antarctica thrives a rich and complex array of plants and animals. But what will happen to all those creatures if global warming reduces the ice-cover, as is predicted for coming decades?
It's now clear that ice plays a major role in the ecology of shallow Antarctic marine systems, by reducing light penetration to the waters beneath.
The team has found marked differences in the composition of marine communities along a gradient of ice-cover.
The object of fascination for most is the DNA molecule. But in solution, DNA, the genetic material that hold the detailed instructions for virtually all life, is a twisted knot, looking more like a battered ball of yarn than the famous double helix. To study it, scientists generally are forced to work with collections of molecules floating in solution, and there is no easy way to precisely single out individual molecules for study. Now, however, scientists have developed a quick, inexpensive and efficient method to extract single DNA molecules and position them in nanoscale troughs or "slits," where they can be easily analyzed and sequenced.
By using cages to experimentally control the access of fish to coral reefs, researchers have assessed the role of fish "grazing" in the ability of reefs to successfully recover from potentially devastating coral-bleaching events related to rises in ocean temperatures. The findings, reported by a group led by Terry Hughes of James Cook University in Australia, will appear in Current Biology online on February 8th.
The Norwegian government has revealed the architectural design for the Svalbard International Seed Vault, to be carved deep into frozen rock on an island not far from the North Pole. The entrance to the "fail-safe" seed vault will "gleam like a gem in the midnight sun," signaling a priceless treasure within: seed samples of nearly every food crop of every country. The vault is designed to protect the agricultural heritage of humankind -- the seeds essential to agriculture of every nation.
Got the PDF. Thank you.