The biochemistry and neurology of memory

My juices have been flowing.  Sluggishly, it has to be said, but flowing, and restoring to conscious memory a few odd facts about the nature of memory that I’ve come across over the years. I’ve cattle-prodded my faulty memory too with a brief surf over several websites.

One intriguing fact came (I think) from an essay by Lewis Thomas in his sparkling series called “Notes of a Biology Watcher” that ran for several years in the 1980s in the New England Journal of Medicine, and collected in books, twice won the Pulitzer Prize. Lewis Thomas told the story of a very primitive organism, a member of the Fluke species, that can be “taught” (or conditioned) to avoid a small electric shock.  I think this organism is called Planaria but I’ve forgotten, and can’t go to the source to check because I gave the book to my grandson Peter; I’ll ask him to look it up and let me know. Once the organism has been conditioned to avoid the small electric shock, it is ground into microscopic fragments in a blender, and fed to a living organism of the same species. The living organism “remembers” how to avoid the unpleasant electric shock. This demonstrates that memory is a biochemical substance, or at any rate, it is in this particular species. When I first came across this intriguing fact I suggested to Wendy, who remembered a social occasion I’d totally forgotten, that if I reduced her to molecular elements in a blender and ate the blended bits, maybe I’d remember the social occasion I’d forgotten. She retorted that if she ate my blended bits and pieces she’d “remember” all the phone numbers I had in my head that she always had to look up. (According to Wikipedia, the research that demonstrated this intriguing observation on Planaria can’t be replicated, so it’s discredited. Pity).

Neuroscientists have demonstrated that in humans the hippocampus, amygdala, and mammillary bodies in the base of the brain are involved in processing and storing particular aspects of memory. In early September 2005 I had a TIA (transient ischemic attack) a vascular lesion that was shown by MRI (brain scan) to have caused multiple small infarcts (regions where tissue died because it was deprived of blood supply) in the base of my brain. Since then my memory has been defective in at least two distinct ways. The first is that I lost all my rather mediocre proficiency in languages other than my mother tongue: my ability to receive and transmit in German and Italian, which had been enough to enable survival in Germany and Italy, vanished altogether; so did my ability to understand spoken French. I’d never been able to speak in French to other people but could understand spoken French quite well. The second defect is loss of memory of whole chapters in my life experience. Reading my letters to Wendy in 1955-56 I came across several about a trip I made to the Gippsland, a district south-east of Melbourne, in Victoria, early in 1956. I’d completely forgotten this trip, was fascinated to read my description of it, but I am mystified about why I went there. Was it work-related or a holiday? I have no idea. All memory of it has been expunged and my letters don’t say. 

My ability to remember things I've read seems to be better than my ability to remember experiences I've had. This is very odd and quite disconcerting. What, if anything, does it say about how (and where in the brain) memories are stored? Maybe a reader of this post can enlighten me.

That defined regions in the base of the brain are involved in processing and storing memories explains why we don’t have any memory of events in the first few years of life: these regions don’t fully develop until several years after birth. People who say they “remember” life in the womb or “remember” being born are exercising their imagination or have brains that developed abnormally early. There’s much more about memory on the web but I’ve said enough, indeed probably too much to clutter my memoirs with technical details. It’s been fun and it’s been interesting to delve into a few details, but that’s all Folks!