Another year has passed since 9/11. It is amazing that it has been 12 years since that day. I bet that most of you remember exactly what you were doing on that morning. You likely remember numerous specific details of that morning as well, such as what you were wearing. Now try to remember what was going on during a random day, let’s pick March 8, 2005. Most of you probably have no idea.
The brain’s process of creating memories is fascinating. There are several areas of the brain responsible for memory. Memories begin through a group of nerves in the brain called the “hippocampus”. When we learn something new, the information is consolidated there and then further links through the cortex are established. Associated smells go to the olfactory cortex; visual cues go to visual part of the cortex, etc. These paths all converge to give us a new memory that contains several details. An example would be the first time a person sees the ocean. The sight of the water, sound of the waves, feel of the sand, smell of the beach all get consolidated and when the person thinks of the ocean again, the brain’s memory circuits activate and a memory of the ocean that includes the senses is retrieved.
The information is also processed along a path called the Papez circuit. This circuit includes the limbic system which is associated with emotional associations. Therefore the memory of the ocean will also include how it felt to be at the beach and the spatial orientation of the beach. The more a person thinks of the memory, the more the information flows through the circuits and the more the memories are strengthened and eventually they become part of long-term memory. Aspects of many memories tend to fade over time. We may forget the day or even year of an event. This is because we are not consciously thinking of these things and therefore not continuing to strengthen the memories. Over time the long-term memory may only recall small snapshots of the past.
So why do we remember events that elicit powerful feelings so well? This is especially true related to terrifying or life-threatening situations. These situations tend to stimulate the brain to activate the sympathetic nervous system. This is the part of the system related to adrenaline and stress hormones. These chemicals prepare the body for stress, they activate more blood to flow to the muscles, and the cardiopulmonary system revs up. In the brain, the amygdala gets stimulated.
One function of the amygdala is to facilitate the formation and storage of memories associated with emotional events, especially powerful ones such as traumatic experiences. It additionally may enhance the ability of other brain regions to consolidate memories of those events. Other animals have this ability as well. Take dogs for example. Their ability to learn and memorize day-to-day commands or information is very limited and takes repetition for even simple things. If a dog gets abused, however, that dog will remain scared of that person, the area it happened, or the device used in the abuse for the rest of his or her life.
Our ability to remember is therefore selective. There is a good reason for this. We need to form quick and strong memories of events or things that could threaten our lives. There is a survival benefit to being able to do that. Alternatively, this also explains why most of us have trouble learning boring things. Not only are adrenaline levels low, but the brain is likely releasing “let me go to sleep” hormones or “can I go now?” hormones.
While there is a survival advantage to our selective memory, there is a potential major disadvantage. Stress hormones, can increase anxiety, fear and irritability. Memories can be stored with excessive adrenaline and this can lead to Posttraumatic Stress Disorder (PTSD). This is a state of too much adrenaline and can lead to severe problems, but that is a topic for another article.
We remember 9/11 because of how unbelievably sad, horrific and terrifying that day was. We remember and honor the victims to help with closure. We remember it every year because there is a certain level of healing of our feelings by doing that. Each anniversary, we talk to friends or loved ones about it, we see that around the world people feel the same; tearful, heart-broken and scared. It normalizes our own feelings and generally, people like to feel “normal”.
Here’s to the hope none of us ever has to register anything remotely like that in our memories again.