No one is certain if it was 1529 or 1530 when Giulio Cesare Aranzi was born. The baby’s father, Ottaviano di Jacopo Aranzio, was poor but married to Maria Maggi, the niece of the wealthy and famous surgeon Bartolomeo Maggi, the principal court physician of Pope Julius III. Having a powerful uncle led to an education for young Giulio consistent with his considerable intelligence and it wasn’t long before he was professor of both surgery and medicine at the University of Bologna and not long before he put Italy on the map as the world center of anatomical information for his many discoveries a few of which are: the blood of the mother and fetus are kept separate during pregnancy; the walls of the heart are impermeable to blood flow; there is a part of the brain whose shape is reminiscent of a sea horse, hippo for horse, kampos for sea monster, hippocampus.
The word hippocampus made the front page of the New York Times several days ago. Why?
The brain is packed tightly with cells called neurons, in the range of 100 billion of them with each one having large numbers of connections to other neurons. Imagine Scotia Power having an electrical network of that complexity. And, in fact, neurons make up an electrical network but instead of electrons moving through wires, the “current” is carried by chemicals with positive charges, like the sodium ions, Na+ in table salt, NaCl. The way these ions move around defines who we are, how we move, what we say, what we think about, what we believe, how we know how to light the wood stove and change a tire, or a diaper, how we remember our prayers, how we remember what has happened to us over the years, how we feel about a summer breeze or a friend, or a child or a spouse, and all else - everything.
In research centered in Tel-Aviv and Los Angeles people with epileptic seizures were being treated with microelectrodes imbedded deep in their brains to try and identify the sources of the seizures. In the period between seizures researchers asked the patients to watch popular video clips. The microelectrodes would signal (by lighting up a sensor) when ions starting moving in a single neuron in contact with the microelectrode. The lighting up was mostly by neurons in that sea horse shaped part of the brain that Aranzi had discovered, the hippocampus. And differing neurons were activated by the different video clips the patients were exposed to: Tom Cruise, The Simpsons, Michael Jordan, Bush, Madonna, Seinfeld, and so on. Then each person was relieved of the pop-culture/political onslaught for several minutes after which they were asked to recall what they had watched. The researchers were astonished to find that they could predict the video clip to be mentioned ahead of the person mentioning it, because the same neurons lighted up. That’s a direct connection, the first ever seen, between a neuron’s actions and human recollection.
At almost the same time researchers were investigating these epileptic patients, other scientists at Rutgers University in New Jersey were looking at microelectrodes lighting up from neuron firings in the hippocampus of the brains of rats. When the rats ran around a wheel the sensors were dark, nothing to remember, but when the rats entered a maze and had to make a choice of which way to go, then the sensors showed certain groups of neurons firing. And after a while when the rats were returned to the maze, the direction the rat took when coming to that turnoff could be predicted by the firing of the same neurons. If another set of neurons fired, then the rat turned the other way. The scientists who studied the epileptic patients knew of this work on rodents and thinking about Darwinian evolution wrote: “The hippocampal machinery used in spatial navigation in rodents may have been preserved in humans but put to a more elaborate and abstract use.”
The fact that the hippocampus is associated with memory is long known. In fact, a researcher in Montreal, at McGill, Brenda Milner, now ninety years old, started almost fifty years ago to investigate a man (HM) who had undergone surgery in an attempt to stem an extreme case of epilepsy. The surgery removed the hippocampus region of his brain and other areas as well. Though it greatly helped the epilepsy the surgery also entirely removed HM’s ability to remember things that had just happened to him. Remarkably he could be taught things involving manual tasks and even though he could not remember learning the task, he was able to carry out the task. Milner observed all kinds of remarkable contradictions over those years. And her disciples have carried on in work from University College London. Scientists have used brain imaging technology to study the brains of taxi drivers who in trying to make a better living shifted from minicabs to those big old black London taxis. To do this they had to spend about two years in a training called “being on the Knowledge,” and to pass a test showing recall of thousands of places within six miles of Charing Cross in central London and how to get there. The imaging results showed an increase in the number of neurons, gray matter as it is put, in one region of the hippocampus at the expense of gray matter in another region for those who stuck with the course of study and passed the test, compared to those who dropped out. And more than that, there was an increase of gray matter in this hippocampal area for those drivers with increasing time driving these big black taxis in this part of London. These results suggest that the old adage to use it or lose it may not only apply to muscles but to the brain as well, which is increasingly seen as an organ that can change according to how it is used.
Mark M. Green (w12thstreet@gmail.com) is a member of the Canadian Science Writers Association who lives in New York City and South West Margaree. Earlier columns can be found at http://blogs.poly.edu/markgreen.
One Comment
Excellently written article. Wish my neurons were not disappearing so fast. “Use them or lost them” appears to be true, although old age damage to the memory seems to be winning out.