Added 1 new A* page:A couple recent, interesting science articles from the BBC!|
Violent end as young stars dramatically collide - Two baby stars in the constellation Orion collided 500 years ago, and their spectacular fireworks are reaching Earth telescopes
Rules of memory 'beautifully' rewritten - In 1953, 27-year-old Henry Molaison's (wikipedia.com) hippocampi were largely destroyed during experimental brain surgery intended to cure the severe epileptic seizures he had suffered since a childhood accident. Afterward, it was found that he could no longer form new memories: you could bring him a second dinner (nytimes.com) after the first, and he would eat it, because he no longer remembered having eaten the first; and each day that he met Suzanne Corkin, the scientist who studied him for 46 years (Molaison died in 2009), was, for Henry, the first day that he had met her. When asked in 1986 what the last president he remembered was, after some pondering he answered "Ike"—who was inaugurated in '53. His understanding of the passage of time was hazy: in his later years, when shown his elderly face in a mirror, he would become confused, and finally realize "I'm not a boy."
Before Corkin's research into Henry's impairment, it was through that memory simply happened equally throughout the brain, but her studies of Henry showed that memory formation actually depended upon functioning hippocampi: small organs inside the brain. It also showed that long-term memories resided elsewhere; Molaison actually could remember new information, through a memory trick: "For post-1953 information he was able to modify old memories with new information. For instance, he could add a memory about Jonas Salk by modifying his memory of polio."
The long-term memories were thought to be taken from the hippocampus and moved into the cortex. Now, just recently, scientists using light beams to turn on and off individual neurons in mouse brains found that their memories form simultaneously in the hippocampus AND the cortex—it's just that the ones in the cortex are dormant for several days, and require communication with the hippocampus to "mature." (Perhaps this explains further phenomena found in Molaison's recall; he could, for instance, recall Corkin hazily when prompted, but the best he could guess was that she was "like a senator.") They could turn off the neurons in the hippocampus and the mice would forget a new traumatic event, for instance, but then the mice could remember it several days after the event, using the memory stored in the cortex.