The Neurobiology of: Memory
Shail Bhatt discusses the physiology behind how we form memories, and how this has influenced the history of our species.
Memory is often thought of as one of the best qualities about being human. Taking a stroll down memory lane and thinking back to the good ol’ days, or even remembering someone’s name. Memory helps us function: it helps us remember details, imbibe certain actions and incorporate them into our daily lives. It also helps us acquire and maintain the necessary skills needed to survive. But have you ever wondered how memories are actually stored? How we are able to remember dozens of phone numbers, names, lyrics, scientific theories, or even simpler, phrases and sentences? Our brain is believed to have a library of sorts, where we house all of these memories, but how are they organised, and how are they accessed whenever we recall something?
In technical terms, memory is the ability to process, store and recall information in the brain. Each of these characteristics has its own distinct process. In general, each memory consists of a specific network of neurons. The processing, or encoding, of information begins when we sense and perceive, and respond in a specific way. If a person is paying close attention, neurons, under the regulation of the thalamus and the frontal lobe in the brain, fire more frequently, and the event is encoded into our memory more easily. The sensations felt are analysed in the cortex region, and the wide range of emotions felt in response to a single incident are compiled into a single memory in the hippocampus. The hippocampus, the sorter and organiser of information, simultaneously makes two copies of the memory: one for the short-term and the other for the long-term.
The preservation of memory isn’t a typical storage unit of sorts. Memories are stored between the connections of neurons. In between this encoding and storage pathway, memories must be consolidated, through which they can be stabilised, and synapses can be strengthened. Through potentiation, where the synchronised firing of a group of neurons causes the creation of a pattern, the very same neurons are more likely to fire in the same order again in the future. Long-term potentiation is when this pattern becomes so repetitive that it becomes almost intuitive.
These experiences can have a myriad of molecular effects, including a process known as synaptic plasticity, where the brain is able to build and destroy synapses, or connections, between neurons. Memory storage, therefore, is a very delicate process that requires continuous reconstruction and reclassification of neuronal networks. When we forget things, or fail to remember them, it is because our brains have either encoded this information incorrectly, have reclassified them with errors, or are unable to retrieve that specific order of neuronal firing.
Specifically, when we recall memories, we are accessing these particular neurons. This occurs as our brains use neurotransmitters and other molecules to reconstruct the memory by accessing different areas of the brain. The more they recall, the stronger the pathway, causing the memory to be stored as long-term. However, whenever we recall an incident, the replays are often blended with elements in the present, including emotion and awareness; this is how memories can often get distorted with time.
Memories are extremely associative, which means that we tend to seek patterns and connections between unrelated items. For example, when we try to remember faces and names, and associate them with incidents and locations from our past, we are trying to build connections. By using devices like mnemonics or rhymes, we can create relationships between different items and remember them easily.
Overall, memory is a wonderful thing. For animals, memory allows them to remember locations and certain aggressive or defensive practices, which is a huge evolutionary advantage. For humans though, not only does memory serve an evolutionary purpose of learning certain skills and reasoning capabilities, but it also aids in a more emotional, personal way. Apart from helping us remember the barrage of equations and theories, it helps us remember and cherish precious memories from our past. These memories define who we are in the present, and it is inconceivable to imagine a world without them.