研究アラカルト 11 The early neuroanatomists had a vivid imagination. Upon dissecting one part of the brain, they decided to call it the hippocampus or sea horse. Others saw it as the horns of a ram and called it cornu Ammonis or Ammon’s horn - horn god in ancient Egypt. Turns out, they were not that far off, both in terms of the overall shape but more importantly with regards to its functional organization. At least in the rodent brain (in which i do my research), the hippocampus starts at the top of the brain and twists all the way to the bottom closely resembling a seahorse of ram’s horn, while the rings seen on the seahorse or horn have to do with the actual inputs and outputs to the hippocampus from the rest of the brain. Upon dissenting my first brain and seeing the hippocampus with my own two eyes I was hooked - it was amazingly beautiful. As a graduate student, I joined Dr. Jonathan Winson’s Laboratory at Rockefeller University in New York who was interested in sleep and more precisely, what role sleep may play in memory. During sleep the brain is not at rest, as most would have thought, but rather it is very active - in humans there are thoughts, dreams, etc. Also neuronal activity does not cease but rather it is increased. What is the reason for all this? A clue to hippocampal function was the discovery by Penfield and Milner in the 1950’s that removal of the hippocampus, in patient H.M. for the alleviation of seizures, totally eliminated the ability to form new memories. A second clue was the discovery by O’keefe in the early 1970’s that the activity of hippocampal cells is correlated with an animal’s location in space - in general these cells are almost totally silent but increase their firing rates dramatically when the animal goes to a certain part of its environment, i.e., ‘place cells’. Upon implanting electrodes in animals and recording the first place cells I was blown away. The Role of Sleep in Memory. That thoughts and dreams may occur in sleep suggests that they may have something to do with learning and memory processes. 研究アラカルト Dissecting the Hippocampus Constantine Pavlides, Ph.D. Behavioral Neuroscience パブリデス コンスタンティン
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