One of the faculties of mind that is extremely puzzling is our capacity to remember. Jane Austen knew this. In _Mansfield Park_, she wrote, "If any one faculty of our nature may be called more wonderful than the rest, I do think it is memory... We are, to be sure, a miracle every way; but our powers of recollecting and of forgetting do seem peculiarly past finding out." Past finding out two hundred years ago, yes, and not nearly fully found out now, but memory is gradually yielding its secrets. James L. McGaugh is the director of the Center for the Neurobiology of Learning and Memory at the University of California, and he has written a primer, _Memory and Emotion: The Making of Lasting Memories_ (Columbia University Press), which is a fine summary of how some of the mysteries of memory are being tackled. He has written "for a general readership" (the book is in the "Maps of the Mind" series), but the subject will be a foreign one for most readers, and there are pithy pages that his general readers may have to struggle through. For the most part, though, McGaugh tells good anecdotes and admirably makes clear some of the most hidden of mental processes, and the explanations help us wonder anew at the remarkable capacities that every one of us takes for granted.
It is certainly a field in which people are interested. There are plenty of books with titles like _Boost Your Memory Now_, and the health stores do a fine business in herbal treatments that are supposed to make our memories better, with little evidence they work. There may be drugs that improve specific memories, however, or decrease their consolidation. Much of the research has been done on rats; evolutionarily, their brains wound up much like ours, just smaller and less complex. Rats can be trained to do such memory-requiring tasks as maze-running and then can be fiddled with in ways that humans cannot. Such drugs as strychnine, a central nervous system stimulant, can be given immediately _after_ maze training (that is, after all the learning exercise has been done), and the rats remember better what they learned during the training. Giving the strychnine hours after the training does nothing; the brains must have a consolidation phase during which the memory is laid down. Other experiments show that a drug like propranolol, used to lower blood pressure because it counteracts the body's store of epinephrine (also known as adrenaline), can counteract epinephrine's capacity to help consolidate memories. Giving propranolol after an emotional memory test blocks the enhancement boost that emotion gives to memory. This is not an academic exercise. Emergency room victims of trauma, if given propranolol, are less likely to have symptoms of post-traumatic stress disorder.
In such ways is memory yielding its secrets. In his review, McGaugh quite rightly refers to the important work of Susan Loftus that shows that false memories can be implanted, especially in children. If you go to a family reunion, it does not take long to learn that some people remember important events one way, and others another contradictory way, but the memories are really there, false or not. Implanting such seemingly real memories is the way that bogus therapists convince their patients that, say, they have received Satanic abuse as children. Eyewitness testimony has been shown to be terribly fallible, now that we have video cameras and DNA testing. But McGaugh and others have been able to discover some secrets about how generally reliable a servant memory is and how it is able to do its job. His volume allows us the pleasing exercise of picking up from a leader in the field just how much research has been accomplished, and of catching a bit of his enthusiasm for his work.