Excerpt from Gene Genie
‘…our procedure is heavily focused on the hippocampus.’
‘I know that’s in our brain, doesn’t hippo means horse?’
‘Yes, the hippocampus is part of the forebrain, the temporal lobe; and its use of ‘hippo’ is because it has a structure that looks a bit like a seahorse. Anyway, it’s associated with our sense of smell, our olfactory system, but it is absolutely central to memory and emotion. Intriguingly when you examine it carefully, it looks almost as if it was a later ‘bolt-on’ goody to our brain, something our creators installed to give us new abilities. The cortex narrows right down to one layer there and is more tightly-packed in terms of neurons than any other part of the brain. It definitely looks as if it were an upgrade to me.’
The technicians were performing the same connections to Marsha’s scalp and soon all that would remain would be for the software to do its work. Stevie’s DNA had been ideal for Marsha’s needs. All the tests of her physiology had proven perfect; this was a woman in her prime, now this gorgeous body was going to become Marsha’s.
Marsha continued to describe her intentions in the belief that this would keep Stevie calm. ‘If you disconnect or damage the hippocampus then you can no longer form any new memories. Much of the theta wave activity happens here and in particular its supra-mamillary nucleus. The hippocampus connects in and out to much of the rest of the brain through the entorhinal complex, and receives its theta rhythm from the medial septum.’
‘OK you lost me with all those names. What do they do?’
‘Always to the point, that’s one of the things that sets you apart from the others. You have to start by distinguishing some subtleties between learning and memory. At its simplest you can start the distinction by saying that to learn Spanish you have to study it, but to speak it you access the memory of what you have learnt. Why I say it is subtle is because of course your accumulation of experiences and memories is often used in the process of inference to develop other learning. So it’s not an absolutely clear distinction, but you have to have memory for this learning or inference, and many other processes, to be effective.’
Stevie was trying to follow the description but found her mind kept wandering. ‘That’s all OK unless your ability to recall these memories becomes wayward! My grandfather had dementia and his access to any sort of memory was very variable.’
‘True, but you need to be aware that our memories come in various forms. First there’s our sensory memory at the point that we see, hear, smell, taste or touch something. We hold on to that sort of memory usually only for milliseconds. It works just long enough to perceive what it was that we sensed, then unless the brain calls for some action the memory is largely discarded. Then there’s our short-term memory which kicks in to record each of our experiences and events as we have them, recording the topography of where we are and so on. It has been shown that this first gets filed directly within the hippocampus. We have the capacity to hold just a little more than a half-dozen such topics simultaneously and each is usually only retained there for less than thirty seconds.’
‘That’s what most people assume is my capacity, but that’s entirely based upon my hair colour.’
‘Men are pigs! Of course we all lose those short-term memories unless we choose to file them away into our long-term memory. Once successfully captured there then with regular maintenance a memory can last for our whole lifespan. It’s how we store our knowledge of words, physical techniques and places. This sending something to your long-term memory is also processed via the hippocampus but then it is filed elsewhere in the brain.
‘Our long-term memory is then usually sub-classified into two sub-types. There is the declarative memory, the term for those things you can call up and describe verbally. Then there are non-declarative memories. These are those that allow us to recall things like how to ride a bike or iron a shirt.’
Stevie was intrigued by the discussion, ‘What about those memories that you don’t want to recall? And what about the way in which we create false memories convincing ourselves that we did something which we actually only ever imagined, perhaps just read it somewhere, or saw it in a movie? “Is it real or is it Memorex?” my father used to say.’
‘Now you’re moving into that other hippocampus role, that of our emotions. Most of those are deep-rooted protection mechanisms. For instance if you are startled by a loud noise then your brain pauses everything else that you were doing while it assesses the source and form of any potential threat. Almost immediately it draws on memory to decide whether the right course is to freeze, fight or flee. There is no doubt that we are able to store memories more readily and over a much longer term when emotions are evoked by an experience. Our amygdala comes into play here. Among other things it activates our adrenal system which not only helps with any fleeing or fighting, but also assists the hippocampus in its process of recording a memory.’
Marsha was almost fully prepped yet still wanted to finish the discussion.
‘As I said the hippocampus clearly handles short-term memories and is key to the process of them being transferred elsewhere so that they become long-term. What we are therefore wishing to achieve today is not to interfere with your sensory or short-term memory processes. We also want to preserve all your useful declarative and non-declarative long-term memory, while we overlay my own.’
The technicians having completed their preparations now carefully put the headsets on both the subjects and placed a sort of hood over each of their heads.
Stevie’s last comment as they attached her hood was, ‘Where did you get these? They look like something out of a kitsch 1950s hair salon?’