Our brains store the feelings and experiences associated with past events within specific neural networks; this information constitutes memory. Through memory, we are able to know who we are, what we have experienced, what we like and what we dislike.

The currently widely accepted three-stage model of the memory process is based on the theoretical model proposed by Richard Atkinson and Richard Shiffrin in 1968. It comprises three stages: encoding, storage and retrieval.

• Encoding: The process of converting perceived information into a form that can be stored. This involves converting external stimuli into neural signals and establishing relevant connections within the brain.

• Storage: Storing the encoded information in specific regions of the brain or neural networks. This can be short-term memory (more transient) or long-term memory (relatively enduring).

• Retrieval: Extracting stored information for use. This involves locating a specific memory from a vast amount of stored information.

Human memory is influenced by many factors, including the action of neurotransmitters, the strength of synaptic connections, and interactions between brain regions. Furthermore, emotions, moods and experiences also influence the formation and storage of memories.

Depending on their duration, memories are categorised into two types: working memory (short-term memory) and long-term memory. These represent two distinct memory storage systems within our brains. They differ significantly in terms of duration, capacity and processing methods.

Duration:

• Short-term memory: Short-term memory is relatively fleeting, typically lasting only a few seconds to one or two minutes, unless reinforced by repetition or focused attention.

• Long-term memory: Long-term memory is relatively enduring, lasting from several hours to several decades.

Capacity:

• Short-term memory: Short-term memory has limited capacity, typically accommodating only a finite number of information units, generally estimated at 7±2 units.

• Long-term memory: Long-term memory has a very large capacity and can store vast amounts of information, including facts, skills and experiences.

• Processing:

• Short-term memory: Information is retained in short-term memory in a relatively raw form, usually without being processed or organised.

• Long-term memory: Long-term memory undergoes deeper processing and organisation and may be linked to other existing knowledge and memories.

• Impact of impairment:

• Short-term memory: It is susceptible to forgetting due to factors such as distraction, interference or sensory overload.

• Long-term memory: Whilst relatively stable, it can be affected by specific brain injuries, illnesses or neurodegenerative diseases, which may lead to the forgetting or loss of some or all long-term memories.

In summary, short-term memory refers to information temporarily retained in the brain, usually for the purpose of carrying out immediate tasks, whilst long-term memory constitutes a relatively enduring form of storage that is crucial for learning, mastering skills and everyday life.

When it comes to amnesia, I believe most of us are familiar with the concept; it is frequently depicted in films, television programmes and literary works, where the male or female lead forgets who they are following an accident, meets their soulmate by chance, and lives happily ever after. But what is life really like for people suffering from amnesia in real life?

Henry Molaison: commonly known as H.M., was one of the most famous cases of amnesia in the 20th century. At the age of seven, a cycling accident left him with intractable epilepsy. To alleviate his epileptic symptoms, his doctor at the time, William B. Scoville, decided to perform a bilateral medial temporal lobectomy, during which two-thirds of his hippocampus, the parahippocampal gyrus, the entorhinal cortex, the piriform cortex and the amygdala were removed.

However, this resulted in him losing the ability to convert new information into long-term memory. Although he was able to recall some early memories, he had almost no recollection of events that occurred after the operation.

Clive Wearing, a British musician, suffered damage to both temporal lobes in 1985 as a result of encephalitis, which led to severe amnesia. He lost almost all of his short-term and long-term memory, causing him to forget his surroundings and experiences every few seconds.

In a radio programme in 2005, Wearing said:

You’re the first human beings I’ve seen, the three of you. Two men and one lady. The first … people I’ve seen since I’ve been ill. No difference between day and night. No thoughts at all. No dreams. Day and night, the same – a blank. Precisely like death.

Is it very hard?

No. It is exactly the same as being dead, which is not difficult, is it? To be dead is easy. You do nothing at all. You cannot do anything when you are dead. It has been the same. Exactly.

Do you miss your old life?

Yes. But I’ve never been conscious enough to think about it. So I’ve never been bored or upset. I’ve never done anything at all; it’s exactly the same as death. Not even dreams. Day and night, it’s all the same.

When you miss your old life, you say, ‘Yes, I miss my old life’—what is it that you miss?

The fact that I was a musician. And in love.

In contrast to those who suffer from amnesia, there is also a group of people in this world who possess an extraordinary memory.

Simonides of Ceos, an ancient Greek poet, was able to remember the position of every person in a room and could even pinpoint their exact locations after the room had collapsed. This story is considered to be the origin of ‘Memory Palace’, which involves constructing mental images or spatial relationships to aid memory.

Marcus Tullius Cicero, the ancient Roman orator and philosopher, once mentioned a technique known as the ‘memory palace’. This is a method of linking information to imaginary buildings or locations, and recalling that information by ‘wandering’ through these places in one’s mind.

These techniques are still widely used today, as illustrated in the American TV series Sherlock.

The stories above highlight the astonishing memory potential of the human brain, whilst also showing us that we can enhance our memory through training and the use of various memory techniques.

Here are some suggestions:

Maintain a healthy lifestyle:

• Eat a balanced diet: Ensure you consume a balanced range of nutrients, particularly foods rich in nutrients essential for brain health, such as omega-3 fatty acids, vitamins and minerals.

• Get sufficient sleep: Maintaining a regular sleep pattern helps to consolidate memories

• Regular exercise: Aerobic exercise promotes blood circulation and enhances brain function.

Keep your brain active:

• Learn new things: Continuously learning new things and challenging your brain stimulates neural network activity.

• Stay sociable: Participating in social activities helps to develop social skills and cognitive abilities.

Use memory techniques:

• Repetition: Repeating what you have learnt several times helps transfer information from short-term to long-term memory.

• Categorisation: Organising information into categories helps the brain establish connections, thereby improving memory retention.

• Association: Linking new knowledge to existing information aids both memory and understanding.

Focus:

• Avoid Distractions: Minimise distractions whilst studying or working to maintain concentration.

• Concentrate: Focus your attention on the task at hand and avoid distractions.

Use of aids:

• Notes and calendars: Write down important information or use a calendar to set reminders.

• Memory games and exercises: Activities such as Sudoku and jigsaw puzzles can help train the brain’s memory capacity.

Managing stress: Learn to manage and alleviate stress to prevent the negative impact of prolonged tension on your memory.

Please remember that improving your memory takes time and sustained effort. As everyone’s brain function and memory capacity differ, the effectiveness of these methods may vary from person to person. If you have particular concerns or difficulties regarding your memory, it is best to seek advice from a healthcare professional.

In this fast-paced era, we often find ourselves lamenting how quickly time passes, realising in the blink of an eye that we have missed so many wonderful moments. However, if we can learn to cherish the present and truly appreciate every detail of life, our memories will become all the more precious. For every memory is a unique treasure in our lives; they accompany us as we grow and bear witness to our joys, sorrows, and everything in between.