Memory

Memory is an essential part of intelligence and learning. IQ, creativity and strategy all depend heavily upon it, as do our social skills and sensory motor abilities.

People tend to make two mistakes when considering how memory works. First, they think of memory as our ‘conscious knowledge’, but both learning and memory contribute to our personality in unconscious as well as conscious ways. Unconscious aspects of memory affect all the functions of our mind and behavior just as much as conscious memories do, [and conscious memories in fact depend on them.] Conscious memories could be looked on as “the details”, while unconscious memories are “the basics” of memory itself.

The second mistake people make in considering memory is assuming that it only uses one brain network, when in fact it uses all of them. Memories put themselves together through association (which is why one part of a memory, such as a smell, can remind you of a whole scene). Particular networks do particular tasks, but not in an isolated fashion; just as neurochemicals all work together to achieve the dynamics of an overall ‘state’, so memory networks integrate together and connect all areas, working in synergy to create a whole memory with all the details.

So there is no ‘individual’ network for storing memory. Your memory uses network 3 for many of its complex tasks including learning, but its storage and access system spreads throughout all networks. There’s a sensible reason for this, and it’s the same reason you keep the tools for changing a wheel in the car’s trunk; not at home in your bedroom. Things and events are stored right on site of the networks that control the functions they are most likely to need to deal with those things and events. This saves the brain time and improves performance.

There are 6 different kinds of memory:

• Sensorimotor or 'muscle' memory
• Spatial memory
• Eidetic or 'pictorial' memory
• Procedural memory
• Declarative memory
• Working memory

All of these except for working memory have both short term (RAM) or long term (LTP) storage.

LTP stands for 'Long Term Potentiation', the technical name for how permanent memories are made. Working memory is like a 'clipboard' only, and has limited room.

The early brain networks deal with most of what used to be known as ‘implicit’ memory, so called because much of it is unconscious. These memories are designed to perform specific functions, like discriminating about sensory stimuli, detecting friend or foe, finding food and so on. They develop as a result of experience but they are based on our hard-wired ‘likes and dislikes’ as a biological organism, and they don’t take up conscious awareness simply because they don’t need to. Sensory motor skills like walking can be learned entirely without conscious thought, and so can finding our way around in familiar territory.

This implicit memory is sometimes called “muscle memory”, and it’s because of it that we all have individual ways of moving, walking, talking and thinking. Body language, the way you smile, and the sound of your voice, are all dependent on habits –the habits of implicit sensory-motor and spatial memory. These and many other aspects of behavior are expressed so automatically, they may seem unchangeable, or believed to be innate. But we should not jump to such conclusions, which forget the roles of plasticity and epigenetics in setting up habits in the first place and maintaining them [If you want to know more, read: “Plasticity & epigenetics: the basics”, in the basics section of the library, or the tutorials.]

Sensorimotor memory

The part of the brain responsible for much of sensory/motor and some spatial memory in N1&2 is the cerebellum. The cerebellum is in the bottom back part of the brain and looks a bit like a lump of cauliflower. It contributes to sensory/motor memory in our control of movement in sensory motor tasks such as walking, throwing and catching, cleaning our teeth, riding a bike, dancing, swimming, driving a car, and all the many basic movements that we must make every day. It is also involved in posture and balance, both of which are modified by experience and contribute to spatial memory.

Two other parts of N 1 & 2 are vital for the formation of memory. They are the brain stem and the hypothalamus. They are important because they control and modulate our hormonal state, enabling us to be alert and aware enough to pay attention and to concentrate and to follow the learning cycle COMP. The brain stem, which flanks the cerebellum all the way up into the centre of the brain, produces most of the neurotransmitters we need for COMP, including dopamine, serotonin, epinephrine [adrenalin] and norepinephrine [noradrenalin]. –[Why have the latter two got two alternative names? –Don’t ask us; we didn’t make them up.]

The hypothalamus, a tiny little cluster of pea-like things that dangles down from the bottom of the brain, is responsible for the ‘brain/body link’ that gives the feedback to and from your memory about what your body is doing and what you want it to do. It signals your body to distribute the hormones that you need to match your body state to your mind state; to keep your heart beating at the correct rate, adjust your breathing, temperature and alertness levels. It joins N1&2 to N3. When you recall a memory, it stimulates your mind and body to reproduce an echo of the hormonal state that went with the original event, and it’s the reason why you still feel excited when you remember exciting events of the past, and get that sudden warm feeling once again when you remember someone you love.

Although N1&2 are involved in making new memories, they are mainly made in N3, and here we move into the central seat of memory and learning. N3 includes the most important departments for memory –the hippocampus and the amygdala [hereafter often referred to by their NH nicknames of ‘hippo’ and ‘amy’].

The Amygdala’s Role in Memory

Studies spanning several decades have shown us the amy’s role in the emotional ‘weighting’ of memory. It gets feedback about what’s going on both directly from the body and via the hypothalamus [that sits very close to it in the brain] and it also responds to neurotransmitters in the rest of the brain.

It needs all this, because one of your amys (we have two) functions mainly to see if anything dodgy or dangerous is going on, and its role in memory involves deciding what is relevant to your wellbeing and what isn’t. It decides how much events matter by looking at what sort of hormonal and neurochemical responses they cause.

Current research is showing that the one on the left [usually, but not always] deals with detecting of, and weighting memories for, beneficial events, and the one on the right [usually] looks for and weights deleterious events. [There is some variety in this in the same way that some people are right- or left-handed.]

The amy puts an ‘importance weighting’ on events like this and this weighting strengthens the memories being made during the event. Strongly weighted memories are more easily retrieved, and their details are clearer and more vivid.

The amy also stores some memories itself, but only those that are relevant to its main job of watching out for you. Its main role in memory is modulating the memories that are being made in the hippo.

The Hippocampus’s Role in Memory

The hippo roughly speaking does three things:

• It enables spatial memory,
• It makes and maintains the eidetic template ‘map’ that all memories are compared against for processing.
• It processes memory -including the making of new memories in learning, turning short term memories into long term ones and moving them to their permanent destination, and facilitating recall.

Overall, what it does best is association.

The Biggest Overall Enemy of Memory

Is anxiety. As we know, a single rush of stress hormones keeps us alert and makes learning and remembering easier, but if the brain is constantly flushed with them the hippocampus will be damaged, with deleterious affects on learning and recall.

It is important to be aware of the limitations of memory because they often go unnoticed. False memories are not unusual; in fact, they are impossible to define, because what is ‘true’ in one circumstance is no longer true in another, and memory is dynamic –that is to say it is updated in the light of our current knowledge and experience. Memories evolve. Falsities creep into almost every mundane recollection but only some of them become apparent [such as when you are sure you remember putting your phone in your bag, but it isn’t there]. Memory does not record real events like a videotape, it re-creates the past, producing a version of events that makes most sense to us from our current perspective. Even long term memories may in the end bear little resemblance to what actually happened. This is a normal and necessary part of maturing and having a broader understanding of reality.

The Second Biggest Problem for Memory

Is sleep-deprivation. Even a small amount of sleep/dream deprivation is bad news for memory and perception, because it results in unpleasant events being remembered more often than pleasant ones! The amy prioritizes ‘danger’ events if the hippo doesn’t have time to fully process all its contents, in fact it even has a special backup network to do this -so if you go short on sleep you will still recall bad events but your memory of good ones will fade. As you can imagine, this can have a very distorting affect on your perception of life in general!

How Much Can Your Memory Improve?

The brain has around 100 trillion connections joining billions of neurons and every single junction has the potential to be part of a memory. New connections can also be forged, so the memory potential capacity of the human brain is effectively pretty massive. In fact, we don’t know the limit yet.

Humans can also maximize their capacity because human memory differs from a computer's in several important ways. For one, it can be selective. Items of interest are retained better than those that are not. So personal and meaningful and creative memories can be held in their billions while dry facts learned at school and never used will fade away. Secondly, the brain works in linkages. If you cannot remember a fact, you can link it to a meaningful memory and use the latter to retrieve the former –this is how mnemonics work.

Self Assessment – Memory

Make a list of the different types of memory, like this:

• sensory motor
• spatial
• eidetic
• procedural
• declarative
• working

Now, read the statements below and follow the instructions after each group of statements.

• I have a good attention span
• I practise sports, dancing, martial arts [or any sensory motor skill] regularly
• I make sure I get good quality sleep and nutrition
• I don’t drink and I don’t take sleeping pills

[For each statement above that describes you, put one point beside ‘sensory motor’, then continue]:

• I can remember faces really well, I always recognise people I’ve met before
• If you show me a shape, I can usually also recognize it upside down or sideways
• I remember stuff from long ago more clearly than recent stuff
• I spent most of my time playing outdoors as a kid, and I still like to be outdoors now [‘Outdoors’ means feet on the ground, head beneath the sky. Being in a vehicle does not count as ‘outdoors’.]

[For each statement above that describes you, put one point beside ‘spatial’, then continue]:

• I’m very good at navigating without a map, and I rarely get lost
• I totally “get” magical and mystical stuff
• I have perfect pitch
• I remember recent stuff more clearly than stuff from long ago

[For each statement above that describes you, put one point beside ‘eidetic’, then continue]:

• Once I’ve had a go at performing a task, I rarely forget how to do it
• I’m methodical, tidy and organized and I rarely lose things
• If I don’t use a machine or a tool for a while, I still don’t forget the instructions
• I learn pest if I’m shown, rather than told, how to do things

[For each statement above that describes you, put one point beside ‘procedural’, then continue]:

• I can remember most facts I read, even if I read them only once
• I usually feel confident about the accuracy of my memory
• I’m better at remembering written or verbal instructions than demonstrations
• I’m aware that my memory of facts seems better than most, and I have a higher than average IQ

[For each statement above that describes you, put one point beside ‘declarative’, then continue]:

• I always remember people’s names, from right after we’re introduced
• I can usually remember a phone number long enough to call back without writing it down
• I rarely worry about anything
• I’m aware of what sort of things I might forget, so I write them down

[For each statement above that describes you, put one point beside ‘working’]

Now look at your list, and see which types of memory are strongest (the ones with most points). You also now know which parts of your memory need the most work.

If you want to know more about learning and memory and how to improve them, read the tutorials.