neurons for memory
New Scientist has an article about a study which is honing in on particular neurons which fire when a person recognises an image of a person.
What I find surprising about this is that the concept is very simple to understand, but it seems to be taking researchers decades to come to the point – they seem surprised to find single neurons firing, as a single neuron is a very simple organism, so how could it hold an abstract concept?
I’ve been doing a lot of thinking about neural networks recently, as I’m working on a robotic gardening machine, which will eventually be put to good use in my own garden to help with my farming.
During my own thinking on this, I’ve also come to the realisation that one single neuron can hold an entire complex memory. When you think of it, a neuron includes not just itself, but its connections to the neurons around it. It is the connections that give a neuron its “intelligence”. A memory, then, is the sum of a neuron’s connections.
Now, it’s not quite as simple as that… the connections take input from other neurons, which in turn are calculated from further connections. In short, a simple yes/no question is actually quite complex when you try to work it out with neurons, but when you get the answer, you can trace back on the connections and get a very rich “reason” for the solution.
For instance, the article mentions Halle Berry. Now, for me, Halle Berry rings several bells – a very nice golf swing in a certain film I can’t remember the name of being the strongest. So, for me at least, the neuron (or small group of neurons) that recognises Halle also links the recognition strongly to that scene. There is also an image of her face, and for some reason, a Michael Jackson video (did she play an Egyptian queen in a video?).
That’s at least four neurons, each of which, if I think about them, will throw up a load more connections.
I think that the various neurons help to keep the memory strong. In Artificial Neural Networks, changing a single neuron is discouraged if it has strong connections to many others, as that change will affect the results of those other neurons.
I think that this is why mnemonic memory works so well. In Mnemonics, in order to remember a single item, you try to link it with something you already know. For example, in the old Memory Palace method, you imagine a walk through your house, or another familiar place. Each room that you enter, you can associate with a certain thought. For more memories, you can associate individual points of interest in the room – shelves, windows, corners, etc.
For instance, let’s say you are to remember a shopping list of “bananas, lightbulbs, baby food, and clothes pegs”, you could associate it with my own house like this: “I walk into my house. Before I can enter, I need to push a huge inflated banana out of the way. On my left is a lavatory. In that room, the walls are covered in blinking lightbulbs. Further on, I reach the main hall. The floor is cobbled with jars of baby food. I walk over the jars into the sitting room, where my girlfriend is sitting, trying to stick as many clothespegs to her face as possible”.
Now, by associating the front door with a banana, for instance, you are doing a few things – you strengthen connections between your front door and bananas, you also connect bananas with your front door, and the absurdity of the situation impresses the connections further. Later on, when you reach the shopping market, you don’t need to remember what was on your list – you just need to go through your memory palace a room at a time.
What is very important about this is that you have used only two items of memory (your front door, and bananas) to remember a third item – that bananas are on your list.
I wonder – Is the sum of possible memories far greater than the sum of neurons available to you? It seems to me that it’s dependant more on the connections than the neurons.
Well its an interesting theory you have. But I have to say that you have neglected to define what a single thought is. If you convert all of the mass of the brain into pure energy via e=mc2 as an optimal case of pure energy (which it is not), then start reducing the full colour pictures stored along with sound and sensations of direction, muscle tension, position, motion,internal and external temperatures, etc into memory needed for storage in terms of energy requirements, you will find that from an energy point of view in pure physics it is not possible to store more than a couple of months worth of memory in the brain. Then given the fact that any given moment of an individuals life is available for the individual to recall either at will or under hypnosis (and I do mean each and every perceptic is available for recall) and is never lost or recorded over, we therefore have to deduce that thought is not confined to the regions of the brain and its neurons. Let alone the fact that somewhere there needs to be an awareness of awareness unit performing these functions seperating us from animals that operate on a purley stimulus -response basis. Now we have entered the realms of philosophy.
interesting, but not realistic.
If you remember two cars, for instance, you do not actually remember the exact details of each car. All you remember is that there were two cars, some facts about what a “car” is, and some points where the two instances of car memory differ from the idea of a car. By the fact that you already know what a car is, you will then be able to describe both of them and be fairly accurate.
No memory is absolutely perfect, and if it was, then your idea might be more realistic. The sheer bandwidth involved in remembering everything in perfect detail would quickly overcome even the strongest brain.
The brain works by abstracting out a lot of the detail that it is exposed to. In most cases, for example, it is enough to remember the gist of a conversation to be able to recreate it with words that are close to what was actually said. In that case, you do not need to remember the actual sound of the words being said, or the various pauses and vocal ticks that the speakers used, but when remembering it, your brain will recreate something which approximates that.
The fact that you can think and remember more than a few months of events is proof that the brain does not work the way you suggest it does. There is no need to drag superstition into it.