The lingering wisps of memory, the subtle newness of a moment…


Hippocampus“Can the simple act of recognizing a face as you walk down the street change the way we think?” Thus opens a story posted on Science Daily. “Or can taking the time to notice something new on our way to work change what we remember about that walk?”

Intriguing questions. The act of recognition, the act of discovery; both can change how we both process information about an act, and how we create a memory of it.

This novel finding suggests that our memory system can adaptively bias its processing towards forming new memories or retrieving old ones based on recent experiences. For example, when you walk into a restaurant or for the first time, your memory system can both encode the details of this new environment as well as allow you to remember a similar one where you recently dined with a friend. The results of this study suggest that what you did right before walking into the restaurant can determine which process is more likely to occur.

Does this mean that we can train ourselves to remember an event or an activity better by planning to notice things? Or by actively looking for something familiar? But remembering and retrieving, while they are both controlled by the hippocampus, they are competitive processes.

Previous scholarship has demonstrated that both encoding new memories and retrieving old ones depend on the same specific brain region — the hippocampus. However, computational models suggest that encoding and retrieval occur under incompatible network processes. In other words, how can the same part of the brain perform two tasks that are at odds with each other?
At the heart of this paradox is distinction between encoding, or forming a new memory, and memory retrieval, or recalling old information. Specifically, encoding is thought to rely on pattern separation, a process that makes overlapping, or similar, representations more distinct, whereas retrieval is thought to depend on pattern completion, a process that increases overlap by reactivating related memory traces.

To take advantage of this would require people to be very alert and aware, all the time, not by accident or coincidentally – as in the recognition of a familiar face encountered in a walk. In his masterwork, Walden (Chapter Two), Henry David Thoreau wrote,

Why is it that men give so poor an account of their day if they have not been slumbering? They are not such poor calculators. If they had not been overcome with drowsiness, they would have performed something. The millions are awake enough for physical labor; but only one in a million is awake enough for effective intellectual exertion, only one in a hundred millions to a poetic or divine life. To be awake is to be alive. I have never yet met a man who was quite awake. How could I have looked him in the face?
We must learn to reawaken and keep ourselves awake, not by mechanical aids, but by an infinite expectation of the dawn, which does not forsake us in our soundest sleep. I know of no more encouraging fact than the unquestionable ability of man to elevate his life by a conscious endeavor. It is something to be able to paint a particular picture, or to carve a statue, and so to make a few objects beautiful; but it is far more glorious to carve and paint the very atmosphere and medium through which we look, which morally we can do. To affect the quality of the day, that is the highest of arts. Every man is tasked to make his life, even in its details, worthy of the contemplation of his most elevated and critical hour. If we refused, or rather used up, such paltry information as we get, the oracles would distinctly inform us how this might be done.

Why is it that seeing one thing can trigger your awareness so that you notice other things, often completely unrelated to the first item?

“We’ve all had the experience of seeing an unexpected familiar face as we walk down the street and much work has been done to understand how it is that we can come to recognize these unexpected events,” said Lila Davachi, an associate professor in NYU’s Department of Psychology and the study’s senior author. “However, what has never been appreciated is that simply seeing that face can have a substantial impact on your future state of mind and can allow you, for example, to notice the new café that just opened on the corner or the new flowers in the garden down the street.”

The same face, the same building, the same tree seen at different times can trigger different responses. One day it might be surprise, another nostalgia, another indifference, and another anger. Why? Perhaps it’s because your brain is busily storing and retrieving all sorts of data, and on the way in or out, the pattern triggers other neurons that activates the emotional activity.

But why or how did this trait evolve? Is it a defence mechanism; something we needed when we came out of the forests into the open plains of Africa? Or is it something older, something from our reptilian past?

Does the same mechanism for memory and awareness affect animals? Dogs and cats, for example, have memories. But can they consciously control their awareness (which raises the question about whether animals are self-aware, to which I reply, yes, but how much awareness they can manipulate remains open to debate).

Another researcher added:

“We spend most of our time surrounded by familiar people, places, and objects, each of which has the potential to cue memories,” added Katherine Duncan, the study’s first author who was an NYU doctoral student at the time of the study and is now a postdoctoral researcher at Columbia University. “So why does the same building sometimes trigger nostalgic reflection but other times can be passed without notice? Our findings suggest that one factor maybe whether your memory system has recently retrieved other, even unrelated, memories or if it was engaged in laying down new ones.”

I remain fascinated by the development of these models of consciousness and the inner workings of neuroscience.

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