How does sound trigger memories?

The brain is the most intriguing organ in the human body. By mass it makes up only a meager 2% of the human body but it contributes an amazing 20% percent to the body’s total energy consumption. It is constantly active and is responsible for all human action including movement, processing and retention of memory as well as processing sensory input.

One interesting way in which the brain works is in how it receives information about the world around us and how that information is stored.

The process by which the brain forms memories can be broken down into three steps:

1. First the memory is encoded into the brain,

2. it is then stored for future use; and

3. eventually that stored memory is retrieved.

Every time we interact with any piece of information, it is initially stored in the short-term memory and depending on how many times you access that memory as you receive it, the brain will either discard it or send it to long term memory.

For instance, when you hear a phone number from a friend and you need to remember it quickly, you repeat it to yourself until it sticks. This is you telling your brain that this information is important and must be sent to long term memory.

On the other hand, you will probably not remember the face of the stranger you passed on the street because that piece of information was not marked as important so your brain just threw it out with any other ‘cerebral trash’.

The processes by which short term memory is eventually taken to long term memory is collectively known as ‘working memory’. This consists of both explicit and implicit memory processes:

• Explicit memory is when we make a deliberate effort to remember something, like facts and experiences which we can consciously know. An example of this in action is when you practice and memorize a speech.

• Implicit memory on the other hand is when you retain memories without consciously recalling them. You can observe this in action when your mouth starts to water when you hear the ice cream truck coming down the road. You do not need to consciously recall how tasty ice cream is for your mind to recall that information.

Most of the processes behind memory formation, happen in the hippocampus and amygdala, which are part of the temporal lobe. What is really fascinating is that the temporal lobe is also the part of the brain responsible for processing auditory information.

Long term memory is stored in the brain as groups of nerves which are organized to fire together in the same pattern that created the original experience. The more nerves there are firing off with different types of information, the more vivid the memory and the longer it lasts.

When factual information is received in conjunction with sensory input, skill, routine, motor action and emotion, the memory formed is connected to a very rich network of neutrons, making it last longer in the mind. This is why memories about facts learnt in school often disappear unless they were repeatedly recalled after they were acquired, but memories about experienced events last longer even though they are not often recalled.

When you hear a sound, similar to a sound associated with a particular event, that sound is matched to memory and it activates that network of neurons along with the associated emotions and other memory details. That is how a howling dog could remind you of the scary werewolf movie you watched ten years ago or how a song can bring you to nostalgic tears when it reminds you of your wedding day.

This incredible way in which memory interacts with sound has quite a number of useful applications:

Nursery rhymes are a powerful teaching tool and throughout history, song has been one of the most effective tools for improving the cognitive functions of young children. Music is also used in therapy to help Alzheimer’s patients communicate and engage with the people around them.

Studies show that musical aptitude and appreciation are often the last mental abilities remaining in those with Alzheimer’s or dementia. Basically speaking, the right music can often help an Alzheimer’s patient exit a state of confusion and sadness and shift them into a happy, nostalgic place as they vividly remember a moment in their younger days when they were surrounded by music, laughter and dancing.

In a future article we will look at the healing power of music and how modern medicine is incorporating this treatment style into their healing methodologies.

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