How are memories formed?

How are memories formed?

It can be hard to function when you are having difficulty remembering things and it is fascinating to understand how our brain works to create memories. 

To understand this, it’s important to first understand that there are two main “types” of memory that we use to function on a daily basis and the two operate together in what is called a “dual process,” which refers to the idea that behaviours and cognitive processes can be the products of two very different pathways.

System 1: unconscious, routine thought processes – think of driving a car when you have been driving for 20 years, or walking.

System 2: conscious, problem-based thought-based processes – think of learning a new language or doing the wordle.

There are also different processes for getting information into the brain (encoding) and getting information out of the brain (retrieval or recall) which depends on whether the memory is System 1 or 2 and where it is stored in the brain.

Where are memories stored in the brain?

Explicit memories (mostly system 2) are stored in three areas of the brain, the hippocampus, the neocortex and the amygdala (see diagram below).  Short-term working memory relies most heavily on the prefrontal cortex.  Implicit memories (predominantly system 1 memories), such as motor memories, rely on the basal ganglia and the cerebellum.

Diagram: Anatomy of the brain


How do we use our memories?

Driving a car is a good example of the “dual-process” theory in action.  When we learned to drive, performing the task was an active process with which we analytically thought about all the mechanics of driving while trying to take in the surrounding environment – I remember it being quite overwhelming!

As we master the mechanical side of driving, that part becomes automatic and we are able to have a conversation while driving, listen to the radio.  We are probably also less likely to crash as we are able to pay more attention to our driving environment while everything else is routine. 

As someone who still has relatively recent memories of teaching three teenagers to drive – the transition phase between a memory moving from System 2 to System 1 can be a debatable and torturous process – with the teenagers believing they have transitioned faster than their parent believes they have!

Diagram: Dual-process memory theory

Memory malfunction

As we get older, it can be harder to remember things and we start to lose trust in our memory – what is going wrong? 

Things can go wrong for our memory in the encoding and the storage process, as well as the retrieval process. 

When we are trying to do too much at once and not paying attention to what we are doing, our short-term memory suffers – think of arriving in the kitchen asking yourself – why did I come here?  Short-term memory only stores about 5-9 pieces of information and usually lasts between 15 and 30 seconds.  This type of memory is critically important for carrying out daily tasks and is often the most noticeable when it misbehaves.  One of the simplest solutions to improving short term memory is doing less, being in the moment and getting good sleep.

To be able to shift short term memory into longer term memory requires our brain to recognise this memory as “worthy of storage,” this is often achieved through repetition or association – remember the school days when we learned mnemonics such as ROYGBIV for the colours of the rainbow.  In a similar way, by association, there is an intersection in Dunedin I am always extra vigilant after experiencing a car crash as a driver with my parents and first baby in the car – action by association!

Problems with retrieving longer-term memories also often arise through tiredness, medications, poor health or a brain incident or infection, long-term alcohol use or nutritional deficiencies (note short-term memories become long-term memories when they are stored in the hippocampus or cortex). 

What is normal memory loss?

As we age, we often blame our memory lapses on “senior moments,” “brain fog” and general age and stage of life.  To a certain extent, this is fair, but I encourage you to have a listen to Episode 14 of our Wellness for the Rest of Us podcast with Alison Liu ( ) on how we can enhance our brain health as we age and what normal might be.

Signs that it is time to speak to a doctor about yourself, or a loved one, include:

  • Asking the same questions over and over again;
  • Getting lost in places a person knows well;
  • Having trouble following recipes or directions;
  • Becoming more confused about time, people, and places;
  • Not taking care of oneself —eating poorly, not bathing, or behaving unsafely;
  • Changes in personality (often noticed by loved one/s).

 Having lost my father to early onset, frontal-lobe dementia, I am acutely aware of how difficult it is to recognise the early stages of dementia and how difficult it can be to receive a diagnosis, but I would urge you, that if you know the brain changes that are happening in yourself or a loved one, are not normal, then persist in seeking help – it can be a very lonely time for all involved.

Latest studies on lifestyle and memory

A study recently (2023) published in PNAS (read here) showed that the consumption of plant flavanols enhanced hippocampal-dependent memory (longer-term stored memory)  in older adults who had poorer diets.  Such flavanols are found in many fruits, such as berries and cocao. The study concluded that dietary flavanols are an important part of the diet for a healthy brain. 

Note anthocyanins, which we often talk about are a sub-class of flavanols and as we often repeat, as we age it is critical to keep up our consumption of a range of plant compounds and fibres, including the flavanol class.

Another study, published in the British Medical Journal (2023) (read here) highlights once more, how critical lifestyle factors are to memory and brain health, with a healthy lifestyle associated with slower brain decline.  In this study, they specifically examined lifestyle factors associated with diet and social connectivity. 

Social connectivity is something we often forget to nurture, but it is as important as we age as when we were youngsters – it’s not just the teenagers who get to party 😊.

 Overall, as frustrating as it can be to struggle in the memory department, there are things that we can do to optimise our memory and brain health as we age.  The critical lifestyle factors of managing diet, sleep, stress, exercise and connectivity make up the pillars of lifestyle health and attention to these help us to live better for longer.

We always welcome your thoughts, questions and feedback – please don’t hesitate to reach out, the day we don’t receive your correspondence with interest and respect would be a sad day indeed!

Please contact Anna 027 4861418 or Darcy at 0275992255.

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