Memory shapes our identity and influences our life choices. We examine how past experiences impact the present and future.
We live our lives mortgaged to memory. Memory has shaped essential elements for living, such as individual personality, relationships, lifestyle habits, and language. Memory is not merely a repository of information; it is a core element that forms our identity. Past experiences create the present self and influence future decisions. Whatever decisions we make are influenced by memories accumulated in the past, and those choices are then accumulated as new memories, forming the trajectory of our lives.
Moving forward in life, we make crucial decisions using memory as our guidebook. When you think about it, isn’t it truly remarkable that everything we’ve seen, touched, and felt is stored somewhere in our minds, imbued with a sense of nostalgia? These memories are not merely tools for reflecting on the past; they are a living database that continuously influences who we are today. For instance, the phenomenon where a specific smell or sound triggers a memory of a particular moment from the past is one example showing how deeply rooted our memories are.
So, how exactly do memories take root in our brains? Do they roll around inside our brains like marbles, neatly stacked and stored in a long-term memory center, as depicted in the animated film ‘Inside Out’? In fact, the process of storing memories in our heads isn’t that different. It uses a memory storage system that progresses from ultra-short-term memory to short-term memory to long-term memory. While applauding Pixar’s creativity for reinterpreting this as storing memory marbles in a memory bank, let’s take a closer look at this structure.
First, all stimuli we see, hear, and feel are converted into electrical signals and transmitted to the brain via the body’s nervous system. These transmitted electrical signals become ultra-short-term memories, leaving only fleeting afterimages in our minds. The everyday scenery around us while walking down the street, or the views seen while riding in a car, are examples of ultra-short-term memories that fade from our minds within seconds. However, among these countless fleeting memories, some provide strong stimulation to the brain. These memories are transferred to short-term memory and retained for several minutes. Short-term memory can be forgotten due to distractions or new stimuli. For example, if you’re trying to memorize a phone number and a friend starts talking to you nearby, you might forget the number.
Short-term memory is not managed by just one part of the brain. Different areas of the brain process memories depending on the specific sensory input or perceived content. When remembering the location of an object, the right frontal lobe becomes active. When performing linguistic activities like remembering words, the left frontal lobe becomes active. Thus, the brain does not have a single central processing unit that collects and processes all short-term memories. Instead, it processes thoughts involving short-term memory through the coordinated activity of multiple brain regions.
Short-term memory is maintained by activating the transmission of substances at synapses within the neural transmission system of neurons, or by continuous transmission within the closed circuit of neurons. Long-term memory, however, is stored not by regulating synaptic activity, but by altering the very structure of the neurons themselves. In other words, short-term memory relies on the transmission activity of neurotransmitters, not physical changes in neurons. Because long-term memory alters the very structure of neurons, it is less susceptible to the influence of other stimuli and can remain in memory for much longer.
In this sense, long-term memory profoundly impacts our identity. For instance, intense events experienced in childhood, stored as long-term memories, can influence our emotions and behaviors even into adulthood. Thus, long-term memory plays a crucial role not only in the accumulation of information but also in shaping our personality.
So where in the brain is this long-term memory stored? Unfortunately, due to the current limitations of brain research, we cannot precisely pinpoint the location of specific memories within our brains. However, existing research indicates that plasticity—the ability of neurons to change—exists throughout the entire nervous system, from the brain to the spinal cord. This means memories can be stored in all these areas. Therefore, even if the brain suffers partial damage, we retain the potential for normal functioning. In fact, the brain can even regenerate damaged areas based on the remaining intact parts. Furthermore, since memories are stored repeatedly in multiple locations within the cerebral cortex, they can be maintained even if one area is compromised.
Of course, certain areas directly influence memory. These include the medial part of the temporal lobe, located on the side of the brain, and the hippocampus. These regions play a role in forming long-term memory. Therefore, if problems arise in these areas, memories formed before the issue remain intact. However, memories formed after the problem occurs become impaired, leading to confusion and memory disorders.
However, it’s crucial to remember that the mysterious and intricate world of the brain remains largely unexplored. The scientific understanding we have of the brain comes from identifying and studying its active regions through anatomy or magnetic resonance imaging. Therefore, research on the brain is still insufficient. When new research methods or directions for the brain are proposed, I believe we might discover new aspects of memory.
Finally, it is important to note that memory does not remain solely as an individual’s experience. Personal memory is intertwined with social memory and is also closely connected to a group’s history and culture. Social memory is the collective recollection of specific events or figures, and it influences our behavior and ways of thinking. This social dimension of memory plays a crucial role not only in shaping individual lives but also in forming the future of the community.
