Memory: how updating what you know about our senses and memory might help strengthen your relationships

Preamble and introduction

Please note: this blog post might be a ‘bit of a ride’.  It was born from self-work I’m doing to adjust how I capture my daily experiences and work with them to build more reliable memories in the post-craniotomy version of my brain.  This work led me to explore related topics through published journals, in podcasts, and other material I’ve found along the way.  You can read on as I make what I think are reasonable connections between evolution and natural selection, brain function and how we experience our surroundings, memory and its fallibility, and how I believe adjusting my own strategies for learning and remembering as I live post-craniotomy with brain cancer has left me with some insight that might help others.  If this sounds interesting, keep reading!  I’ll reference sources for many of the claims within, and you can infer that non-referenced claims imply that they’re based on my understanding and connection of what I’ve experienced or learned:  please consider where relevant so you can draw your own conclusions, I’m happy to hear more thoughts in the comments!

I’ve long been interested in how the brain works and more recently about how the human brain might have evolved into what it is today.  Current discussions about the LONG processes of natural selection include two common themes amongst others: changes in genes (mutations) happen quite randomly rather than being a guided event, but are typically influenced by selective pressures that influence an individual’s ability to pass that gene on to the next generation, and often involve an underlying benefit to genes that provide an advantage in ability for the gene’s owner to optimize resource use and energy expenditure. ^{(1) (2) (3)}  This might seem like a non-obvious starting point for this post, but it reminds me that human brains will have developed over millions of years to be energy efficient – wasted energy is EXPENSIVE when struggling to survive.  Today’s human brains have been selected for through our youthful ancestors as they raised their children.  Below, I’ll relate these ideas to what I thought I knew of how we experience or world, and how I thought I knew memory worked, building on newer models I think can be helpful in sustaining strong and meaningful experiences and relationships.

Our brain and experience of the world

I thought I had a good understanding of how we experience the world, which went something like this: our brain works as a complex interconnected structure of nearly 100 billion neurons (around 80 – 90 billion) that are grouped into regions that take input from our sensory organs – eyes, ears, nose, mouth, fingers, feet, skin, and more – to make sense of the external world then save the memories for later. ^{(4) (5) (6) (7) (8)}  It fascinated me to understand that while our brain has no direct connection to the world, it uses chemical and electric signals from these connected sensory organs to interpret what happens outside, and that we get to experience the richness that fills our lives through our senses.  I thought my brain faithfully and accurately kept a true record of my lived events.  I know now that current models recognize the high energy cost of doing this in real time.  You are probably familiar with using a cell phone for a video-call or to taking photos or videos while the battery level drops as one loosely related example of such a high energy cost.

We have known for decades that our brain takes time to process and interpret input.  The delay in our visual processing helps make animated images come to life, where frame rates faster than about 10 to 12 images per second appear as motion instead of separate images. ^(9) (10).  This  comes from the speed with which the rod and cone cells in our eyes respond to photons of light, the speed with which the amacrine cells and retinal ganglion cells convey this to neurons to deliver the signals to the brain and time spent processing in the brain’s cortex and subcortex. ^(11) (12)  By combining visual and auditory clues, our brain can build a model of things and motion around us necessary to react and avoid injury. ^{(13) (14) (15)}  For more than a hundred years, stage magicians and illusionists have understood how to creatively use this delay with careful distraction to perform acts of ‘magic’ where what happens next is not what we expected, and this provides a wonderful clue into how our brains really work. ⁽¹⁶⁾

A popular current model shows we experience the world in a more predictive mode than a reactive one.  Instead of waiting for inputs to be processed moment-by-moment, the brain compares recent input to years of previous memory and predicts in near-real-time what it thinks will happen next. ⁽¹⁷⁾  I think it’s a pretty cool paradigm shift to understand that we’re constantly predicting the future, rather than just reacting to what we see.  It’s as if we’re seeing a fraction of a second into the future and feels more intuitive to me when I think of those ‘double-take’ moments I’m familiar with when something surprises me.  When my brain predicts what’s next but the input from my eyes and ears doesn’t match, my brain creates that familiar sensation of surprise, and I’m instinctually caused to pay close attention.  In most other cases, my brain predicts what will happen next and after processing the various inputs if the real world matches the prediction, everything seems quite commonplace and doesn’t demand more attention.  By having a baseline threshold for ‘close enough’, my brain can avoid having to deeply process all of the input.

I think I can understand here how this is more energetically efficient, requiring less effort and energy than a rapid near-real-time processing of input to react to.  It makes sense to me also that this predictive model would have allowed early humans to avoid danger (e.g., avoiding an aggressive predator or other physical harm in their environment), thus helping them survive and raise the next generation.  Both the energy efficient model and early survival benefit link to the evolutionary selection forces I started discussing and help me to better understand how this modern way of understanding how the brain works makes intuitive sense.  It makes it easy for me to un-learn what I thought I knew from what I thought and understood my lived experience had been and make me think more about what this means for the memories I form in my daily experiences.

How a predictive brain influences memory development

Much of this section is my own speculation as influenced by what I have read and shared above, what I’ve read about modern understanding of memory, and the work I’ve been doing to re-learn how to form memories with my post-surgery brain.  I quickly learned that the way I make new memories has changed and I have been inspired to learn how to use my new brain.  I shared pieces of how I approach re-learning how to remember in my earlier blog post, My surgery and recovery period, which for me has been about journaling each day, curating my google maps timeline to accurately represent where I’ve been each day, and capturing photos and videos of interesting things to remember each day.  I review these with daily, weekly, and monthly groupings to learn in the same way as I studied in school, when I thought repetition was key to building long-lasting memory.  I occasionally find memories that just don’t quite make sense and where I can’t correlate different pieces without finding conflict, and where I need to re-visit and question the memories I find.

While in school, I learned that repetition can be helpful for memory, and later learned repetition can intentionally or unintentionally modify, create, or edit memories to the point that they are no longer accurate: repetition can behave in unexpected ways. ^{(18) (19) (20)}  I suspect many will be familiar with occasions where we might have re-imagined or re-played versions of an important conversation either before or after it happened, to the point that it’s hard to remember which parts of a conversation were real versus which parts were the rehearsal.  I use my written and digitally captured records to help avoid the potential trap of learning an imagined memory, while diving deeper where I find memories that seem inconsistent with other parts of a given day, week, or month.

The amygdala and influencing stress-related hormones such as β-adrenergic agents, epinephrine, glucocorticoids and more can influence memory storage ⁽²¹⁾ and the effects of repetition change as we age ⁽²²⁾ and potentially contribute to false recognition ^(23) (24).  These and other points should remind us that our memories are fallible, so we should consider this when thinking about memories.  I now wonder whether the predictive nature of the brain means that some memories are more related to the prediction the brain made than of the observed event.  I know from examples in my own life that I’ve shared an experience with a friend and where each of us have slightly different memories of details.  It’s often been easy to assume that it’s because we saw things from our own perspectives and with our own in-built and life-learned biases, such that there’s an observer’s perspective bias. ⁽²⁵⁾

There’s room here to think about how a predictive brain will encode memories, both episodic memory about events and experiences and semantic memory about facts and general learned knowledge. ⁽²⁶⁾  If our episodic memory is informed and built more from our internal prediction of events when the prediction is ‘close enough’ to the observed reality, then it follows that when two people share an experience, each person’s memory is built more from their individual prediction of the experience rather than their shared experience; this might explain why each individual’s recollection of the event can differ.  It also follows that as our own cognitive function changes over time, our brain’s ability to discern a difference between a predicted event and an observed event could contribute to memory formation built on a failed but ‘close enough’ prediction, without correcting for the observed reality.  I’ve not been able to find much published work documenting research in this area, but to me it’s a fascinating potential way of looking at the internal experience of someone living through cognitive decline.

How does this connect to our interpersonal relationships?

I opened by suggesting what I’ve learned might be useful for others, but you’ve likely noticed now that I’ve rambled on about recent advances in brain function and memory storage and retrieval understanding from more of a theory angle without connecting it to daily life and relationships.  I hope the connection to our daily lives and interpersonal relationships isn’t a large jump, and that it’s one that could be useful as we reflect on moments of conflict or unpleasant interactions.

What I think I’m learning is a clearer model that tells me our memories are less solid than I thought.  When I think now of times where I’ve disagreed with a friend, or perhaps had a negative interaction, I’m more able to consider that I’m remembering more about my brain’s prediction of that interaction than a set of objective facts.  My hope is that this current framework and model of how we experience the world around us and how we then encode and retrieve the memories can help us revisit those moments with less certainty about the facts, and to use that to reduce the stress we feel from revisiting them.  We might use it to better understand disagreements when we think we’re debating facts with a friend, but where we’re actually comparing two sets of ‘close enough’ predictions instead of actual events.

I hope also that we can better understand the reality of loved ones whose outward expressions don’t seem to match what we expect.  This might be caused by a mis-match in each of our brains’ predictions given each of our lived experiences.  Many of us will have conversations with people close to us who experience some form of cognitive decline, and my hope is that a better understanding of how we build and remember our reality might make it easier for use to relate better to an unfamiliar or illogical reality.

I’m closing on an optimistic and rather ‘fuzzy’ note and know that those who know me well won’t be surprised.  In finding ways to help myself with my own situation, it’s driven me to read more into things I’m excited and interested in, and my hope is that at least a few readers will be interested in the ideas also.

Thanks for reading along, and please do share your thoughts in the comments!

 

Works Cited

1. Positive and Negative Selection on the Human Genome. Fay, Justin C., Wyckoff, Gerald J. and Wu, Chung-I. 3, 2001, Genetics, Vol. 158, pp. 1227-1234.

2. Selection in Nature: Experimental Manipulations of Natural Populations'. Reznick, David N. and Ghalambor, Cameron K. 3, 2005, Integrative and Comparative Biology, Vol. 45, pp. 456-462.

3. Fabian, Daniel and Flatt, Thomas. The Evolution of Aging. Nature Publishing Group. [Online] [Cited: 2 29, 2024.] http://www.nature.com/scitable/knowledge/library/the-evolution-of-aging-23651151.

4. Module 10: Neuronal Signalling. Berridge, Michael J. 2012, Biochemical Journal, Vol. 6.

5. Patch-Seq Protocol to Analyze the Electrophysiology, Morphology and Transcriptome of Whole Single Neurons Derived From Human Pluripotent Stem Cells. Hurk, Mark van den, et al. 2018, Frontiers in Molecular Neuroscience, Vol. 11, p. 261.

6. Construction of the human forebrain. Jernigan, Terry L. and Stiles, Joan. 2017, Wiley Interdisciplinary Reviews: Cognitive Science, Vol. 8.

7. Tracking How Memories Form. Wolf, Lauren K. 2015, Chemical & Engineering News.

8. The remarkable, yet not extraordinary, human brain as a scaled-up primate brain and its associated cost. Herculano-Houzel, Suzana. 2012, Proceedings of the National Academy of Sciences of the United States of America, Vol. 109, pp. 10661-10668.

9. Group, Gamma, Read, Paul and Meyer, Mark-Paul. Restoration of motion picture film. s.l. : Butterworth-Heinemann, 2000. pp. 24–26.

10. Schuler, Romana Karla. Seeing Motion: A History of Visual Perception in Art and Science. s.l. : Walter de Gruyter GmbH & Co KG.

11. Glycinergic neurons in the human retina. Frederick, Jeanne M., Rayborn, Mary E. and Hollyfield, Joe G. 2, 1984, The Journal of Comparative Neurology, Vol. 227, pp. 159-172.

12. The organization of the retina and visual system. Schmolesky, M.

13. A Comparison of Visual and Auditory Motion Processing in Human Cerebral Cortex. Lewis, James W., Beauchamp, Michael S. and DeYoe, Edgar A. 9, 2000, Cerebral Cortex, Vol. 10, pp. 873-888.

14. The effect of non-visual working memory load on top-down modulation of visual processing. Rissman, Jesse, et al. 7, 2009, Neuropsychologia, Vol. 47, pp. 1637-1646.

15. The human visual system is optimised for processing the spatial information in natural visual images. Parraga, CA, Troscianko, Tom and Tolhurst, David J. 1, 2000, Current Biology, Vol. 10, pp. 35-38.

16. Attention and awareness in stage magic: turning tricks into research. Macknik, Stephen L., et al. 11, 2008, Nature Reviews Neuroscience, Vol. 9, pp. 871-879.

17. Top-Down Predictions in the Cognitive Brain. Kveraga, Kestutis, Ghuman, Avniel Singh and Bar, Moshe. 2, 2007, Brain and Cognition, Vol. 65, pp. 145-168.

18. Not all repetition is alike: Different benefits of repetition in amnesia and normal memory. Verfaellie, Mieke, et al. 3, 2008, Journal of The International Neuropsychological Society, Vol. 14, pp. 365-372.

19. Repetition Suppression and Multi-Voxel Pattern Similarity Differentially Track Implicit and Explicit Visual Memory. Ward, Emily J., Chun, Marvin M. and Kuhl, Brice A. 37, 2013, The Journal of Neuroscience, Vol. 33, pp. 14749-14757.

20. Repetition and laterality effects on recognition memory for words and pictures. Juola, James F. 2, 1973, Memory & Cognition, Vol. 1, pp. 183-192.

21. Involvement of the amygdala in memory storage: Interaction with other brain systems. McGaugh, James L., Cahill, Larry and Roozendaal, Benno. 24, 1996, Proceedings of the National Academy of Sciences of the United States of America, Vol. 93, pp. 13508-13514.

22. Effects of Aging, Message Repetition, and Note-Taking on Memory for Health Information. Morrow, Daniel G., et al. 6, 1999, Journals of Gerontology Series B-psychological Sciences and Social Sciences, Vol. 54, p. 369.

23. On the dual effects of repetition on false recognition. Benjamin, Aaron S. 4, 2001, Journal of Experimental Psychology: Learning, Memory and Cognition, Vol. 27, pp. 941-947.

24. Repetition effects in associative false recognition: Theme-based criterion shifts are the exception, not the rule. Starns, Jeffery J., Hicks, Jason L. and Marsh, Richard L. 6, 2006, Memory, Vol. 14, pp. 742-761.

25. Observer memories may not be for everyone. Radvansky, Gabriel A. and Svob, Connie. 5, 2019, Memory, Vol. 27, pp. 647-659.

26. Episodic and semantic autobiographical memory and everyday memory during late childhood and early adolescence. Willoughby, Karen A., et al. 2012, Frontiers in Psychology, Vol. 3, pp. 53-53.