Abstract
fpsyg-10-02523 November 5, 2019 Time: 17:15 # 1 PERSPECTIVE published: 07 November 2019 doi: 10.3389/fpsyg.2019.02523 Memory: An Extended Definition 1 2 Gregorio Zlotnik * and Aaron Vansintjan * 1 2 Clinique de la Migraine de Montreal, Montreal, QC, Canada, Department of Film, Media and Cultural Studies, Birkbeck, University of London, London, United Kingdom Recent developments in science and technology point to the need to unify, and extend, the definition of memory. On the one hand, molecular neurobiology has shown that memory is largely a neuro-chemical process, which includes conditioning and any form of stored experience. On the other hand, information technology has led many to claim that cognition is also extended, that is, memory may be stored outside of the brain. In this paper, we review these advances and describe an extended definition of memory. This definition is largely accepted in neuroscience but not explicitly stated. In the extended definition, memory is the capacity to store and retrieve information. Does this new definition of memory mean that everything is now a form of memory? We stress Edited by: Gabriel Radvansky, that memory still requires incorporation, that is, in corpore. It is a relationship – where University of Notre Dame, one biological or chemical process is incorporated into another, and changes both in a United States permanent way. Looking at natural and biological processes of incorporation can help Reviewed by: David Copeland, us think of how incorporation of internal and external memory occurs in cognition. We University of Nevada, Las Vegas, further argue that, if we accept that there is such a thing as the storage of information United States Denis Brouillet, outside the brain – and that this organic, dynamic process can also be called “memory” – Paul Valéry University, Montpellier III, then we open the door to a very different world. The mind is not static. The brain, and France the memory it uses, is a work in progress; we are not now who we were then. *Correspondence: Gregorio Zlotnik Keywords: memory, extended cognition, incorporation, storage of information, information technology, [email protected] experience Aaron Vansintjan [email protected] INTRODUCTION Specialty section: This article was submitted to In the short story “Funes, the memorious,” Jorge Luis Borges invites us to imagine a man, Funes, Cognition, who cannot forget anything. The narrator is ashamed in the inexactness of his retelling: his own a section of the journal memory is “remote and weak,” in comparison to that of his subject, which resembles “a stammering Frontiers in Psychology greatness.” Unlike Funes, he says, “we all live by leaving behind” – life is impossible without Received: 26 July 2019 forgetting. He goes on to note that, even though Funes could remember every split second, he Accepted: 24 October 2019 couldn’t classify or abstract from his memories. “To think is to forget a difference, to generalize, to Published: 07 November 2019 abstract.” The reader may be led to wonder how Funes’ brain has the capacity to store all of that Citation: memory. doesn’t it reach its limits at some point? Borges leaves that question to our imagination. Zlotnik G and Vansintjan A (2019) In popular culture, memory is often thought of as some kind of physical thing that is stored in Memory: An Extended Definition. the brain; a subjective, personal experience that we can recall at will. This way of thinking about Front. Psychol. 10:2523. doi: 10.3389/fpsyg.2019.02523 memory has led many to wonder if there is a maximum amount of memories we can have. But, Frontiers in Psychology | www.frontiersin.org 1 November 2019 | Volume 10 | Article 2523 fpsyg-10-02523 November 5, 2019 Time: 17:15 # 2 Zlotnik and Vansintjan Memory: An Extended Definition this idea of memory is at odds with advances in the science categories: sensory, short-term, and long-term. Each of these of memory over the last century: memory isn’t really a fixed kinds of memory have different attributes, for example, sensory thing stored in the brain, but is more of a chemical process memory is not consciously controlled, short-term memory can between neurons, which is not static. What’s more, advances only hold limited information, and long-term memory can store in information technology are pushing our understanding of an indefinite amount of information. memory into new directions. We now talk about memory Key to the emerging science of memory is the question on a hard drive, or as a chemical change between neurons. of how memory is consolidated and processed. Long-term Yet, these different definitions of memory continue to co- storage of memories happens on a synaptic level in most exist. A more narrow definition of memory, as the storage of organisms (Bramham and Messaoudi, 2005), but, in complex experiences in the brain, is increasingly at odds with an extended organisms like ourselves, there is also a second form of memory definition, which acknowledges these advances. However, while consolidation: systems consolidation moves, processes, and more this expanded definition is often implicitly used, it is rarely permanently stores memories (Frankland and Bontempi, 2005). explicitly acknowledged or stated. Today, the question is no Today, there are many models of how memory is consolidated longer, how many memories can we possibly have, but, how is in cognition. Single-system models posit that the hippocampus the vast amount of memory we process on a daily basis integrated supports the neocortex in encoding and storing long-term into cognition? memories through strengthening connections, finally leading the In this paper, we outline these advances and the currently memory to become independent from the hippocampus (Ibid.). accepted definitions of memory, arguing that these necessarily Multiple-trace theory instead proposes that each memory has imply that we should today adopt an extended definition. In the a unique code or memory trace, which continues to involve following, we first describe some key advances in the science the hippocampus to an extent (Hintzman and Block, 1971; of memory, cognitive theory, and information technology. Hintzman, 1986, 1990; Whittlesea, 1987; Versace et al., 2014; These suggest to us that we are already using a unified, and Briglia et al., 2018). In another theory, memory is understood extended, definition of memory, but rarely made explicit. Does as a form of negative entropy or rich energy (Wiener, 1961, this new definition of memory mean that everything is now 1988), which is then processed in a way that minimizes the a form of memory? We argue that looking at natural and expenditure of energy by the brain (Friston, 2010; Van der biological processes of incorporation can help us think of Helm, 2016). Our heightened capacity to store information how incorporation of internal and external memory occurs in may be due to our ability to reduce disorder and process cognition. Finally, we note some of the implications of this large amounts of information rapidly, a necessarily non-linear extended definition of memory. process (Wiener, 1961, 1988). The forgetting and fading of memories is also understood as being an important aspect of the functioning and utility of these memories (Staniloiu BACKGROUND: ADVANCES IN THE and Markowitsch, 2012). As with a computer hard drive, memories can also be “corrupted” – false memories are SCIENCE OF MEMORY commonly studied within forensic psychology (Loftus, 2005). Already in the 19th century, the recognition that the number of Together, these advances highlight how different kinds of neurons in the brain doesn’t increase significantly after reaching memory storage are non-linear – that is, subject to complex adulthood suggested to early neuroanatomists that memories systems interactions – contextual, and plastic. They also shed aren’t primarily stored through the creation of neurons, but light on why, and how, we are able to live with such large rather through the strengthening of connections between neurons quantities of information. It may not be that Funes has the (Ramón y Cajal, 1894). In 1966, the breakthrough discovery of special ability to remember everything, but that he lacks our long-term potentiation (LTP) suggested that memories may be ability to incorporate, and sort through, a potentially infinite encoded in the strength of synaptic signals between neurons amount of information. (Bliss and Lømo, 1973). And so we started understanding The advance of the fields of genetics and epigenetics has also memory as a neuro-chemical process. The studies by Eric given us new metaphors to describe memory. We understand Kandel of the Aplysia californica, for which he won the Nobel DNA as a structure that carries information that we call “genetic prize, for example, show that classical conditioning is a basic code” – kind of like a computer chip for biological processes. form of memory storage and is observable on a molecular Today, the metaphor has come full circle and we can now use level within simple organisms (Kandel et al., 2012). This in DNA to store and extract digital data (Church et al., 2012). effect expanded the definition of memory to include storage The study of epigenetics suggests that simple lifeforms pass on of information in the neural networks of simple lifeforms. memories across generations through genetic code (Klosin et al., Increasingly, researchers are exploring the chemistry behind 2017; Posner et al., 2019), suggesting a need to study whether memory development and recall, suggesting these molecular humans and other complex life forms may do so as well. With processes can lead to psychological adaptations (e.g., Coderre these advances, our understanding of how memory is stored has et al., 2003; Laferrière et al., 2011). expanded once again. Memory is today defined in psychology as the faculty of Further, we can now store memory in places that we haven’t encoding, storing, and retrieving information (Squire, 2009). been able to before. Smartphones, mind-controlled prosthetic Psychologists have found that memory includes three important limbs, and Google Glasses all offer new ways to store information Frontiers in Psychology | www.frontiersin.org 2 November 2019 | Volume 10 | Article 2523 fpsyg-10-02523 November 5, 2019 Time: 17:15 # 3 Zlotnik and Vansintjan Memory: An Extended Definition and thereby interact with our surroundings. Our ability to agency. She realizes that she had seen it out of the corner produce information alters how we perceive the world, with of her eye, and her brain had then processed the information far-reaching implications. As Stephen Hawking, the Nobel while she was thinking of something else, which then triggered prize-winning physicist explained in his 1996 lecture, “Life in the anxiety attack. the universe,” (2). Consider a nerve cell of an A. californica, a kind of What distinguishes us from [our ancestors], is the knowledge sea snail, which is prodded vigorously for a short time period, that we have accumulated over the last 10000 years, and provoking an immediate withdrawal response. Shortly afterward, particularly, over the last three hundred. I think it is legitimate it is prodded less intensely, but, it elicits the same withdrawal to take a broader view, and include externally transmitted response. It is found that the slugs’ nerve cell is sensitive for up information, as well as DNA, in the evolution of the human race to 24 h – the nerve cells “remember” past pain. (Hawking, 1996). Each example illustrates a different kind of chemical, The sheer quantity of available information today, as well biological process. In the first example, an outside stimulus as developments in an understanding of memory – from fixed triggers a stress response for the homeowner. We can surmise and physical to dynamic, chemical, and a process of rich energy that though she didn’t “remember” anything, non-consciously, transfer – lead to a very different picture of memory than the one she did. In the second example, the snail certainly “remembers” we had 100 years ago. Memory seems to exist everywhere, from the provocation, even though this memory is only stored in a few an Aplysia’s ganglion to DNA to a hard drive. cells. But can we really call this memory? To account for these developments, cognitive scientists now However, on closer examination, we are forced to concede that propose that human cognition is actually extended beyond the each of them should be called a form of memory. First, consider brain in ways that theories of the mind did not previously the homeowner: her brain “remembers” something that does not recognize (Clark and Chalmers, 1998; Clark, 2008). This occur to her as a conscious thought. It is clearly a chemical approach is being called 4E cognition (Embodied, Embedded, process occurring in the background. Most would grant that this Extended, and Enactive). For example, enactivism posits that would nevertheless be a form of memory, as it involves recalling cognition is a dynamic interaction between an organism and information stored in her brain. Already, a broader definition of its environment (Varela et al., 1991; Chemero, 2009; Menary, memory is used that does not imply conscious attention. Now, 2010; Rowlands, 2010; Favela and Chemero, 2016; Briglia consider the snail: it is also storing information chemically. Once et al., 2018). According to this framework, cognition is a again, this does not involve a conscious, subjective process of process of incorporation between the environment and the storing and remembering – it is purely reactive, but information body/brain/mind. To be clear, cognition is not incorporated in is being stored and recalled nonetheless. We would need to the surroundings, only the corpus can incorporate, and thus concede that if the homeowner’s experience counts as memory, cognition (or what we call “mind”) is a product of the interaction then the slug’s automatic response does as well. There is in fact between the brain, the body, and the environment. little difference between the first two examples: there is a transfer of information that causes a reaction. Both should be considered forms of memory. EXTENDING MEMORY These developments indicate that we need to reconceptualize our A SLIPPERY SLOPE? definition of memory. What is the difference between trying to recall a childhood experience, and searching for an important If we agree with this expanded definition of memory, then it email archived years ago? This distinction is best represented follows that experience is also a form of stored information, kinds through the difference in how we use the words “memory” and of memory. We are not saying that a particular experience, as an “memories.” Usually, “memories” tends to refer to events recalled event, is a memory. Rather, we here use the word “experience” as from the past, which are seen as more representational and connoted by the phrase “an experienced driver,” an “experienced subjective. In contrast, “memory” now is used to refer to storage writer.” They have a set of experiences, remembered through of information in general, including in DNA, digital information practice, and retrieved when they drive, or write. When we storage, and neuro-chemical processes. Today, science has moved accumulate knowledge, information, and techniques, then the far beyond a popular understanding of memory as fixed, accumulation of those separate processes constitute experience. subjective, and personal. In the extended definition, it is simply This experience involves retrieval of information, conversely, the capacity to store and retrieve information. To illustrate why being experienced is the process of retrieving memory. memory has extended beyond this original use, we want to Under this definition, even immunological and allergy ask the reader: what do a stressed-out driver and a snail have processes may be considered memory. There is a storage of in common? information of the allergen or the viral/bacterial aggressor and (1). A homeowner has been trying to sell her house for a when the aggressor or allergen re-appears there is a cascade year, and worrying about it. One day, she’s driving to work and of inflammatory processes. This can be considered the storage becomes extremely anxious, for no apparent reason. She wasn’t and retrieval of information, and thus a form of memory. This thinking of anything in particular at the time. Confused, she does not contradict the accepted definition of memory within looks around, and notices a billboard advertising a real estate psychology, as it is still seen as the ability to encode, store, and Frontiers in Psychology | www.frontiersin.org 3 November 2019 | Volume 10 | Article 2523 fpsyg-10-02523 November 5, 2019 Time: 17:15 # 4 Zlotnik and Vansintjan Memory: An Extended Definition recall information. Rather, it extends it to processes not just is acknowledged to be a part of memory, and memory is not a bound by the brain. part of conditioning. Memory would become the umbrella for If memory is indeed defined as “the capacity to store and/or learning, conditioning, and other processes of the mind/brain. retrieve information,” then this may lead anyone to ask – what Doing so changes the frame of observation from one which isn’t memory? Wouldn’t this definition of memory be far too understands memory as a narrow, particular process, to one broad, and include a vast range of phenomena? Is the extended which understands it as a dynamic, fluid, and interactive definition of memory, as is being proposed by neurobiologists phenomenon, neither just chemical or digital but integrated and cognitive theorists, a slippery slope? into our experience through multiple media. Second, it helps As we suggested above, however, memory still involves a to conceptualize the relationship between biology, psychology, process of incorporation, that is, requiring a corpus. While cognitive science, and computer science – as all three involve memory may be stored on the cloud, it requires a system studying the transfer of information. of incorporation with the body and therefore the mind. Third, it opens up an interesting way to imagine our own In other words, the “cloud” by itself is not memory, but future. If we accept that there is such a thing as the storage of operates through an infrastructure (laptops, smart phones, information outside the brain – and that this organic, dynamic Google Glasses) that are integrated with the brain-mind through process can also be called “memory” – then we open the door learned processes of storage and recall. The conditioning to a very different world. The mind is not static. Rather, like of an Aplysia’s ganglion is incorporated into an organism. early cells acquiring mitochondria, it incorporates information Memory, it seems, is not just mechanistic, but a dynamic from its surroundings, which in turn changes it. The brain, and process. It is a relationship – where one biological or the memory it uses, is a work in progress; we are not now who chemical process is incorporated into another, and changes we were then. Many have already noted the extent to which both in a permanent way. A broadened definition must we are cyborgs (Harraway, 1991; Clark, 2003, 2005); this neat account for this dynamic relationship between organisms and line between human and technology may become more and their environment. more blurred as we develop specialized tools to store all kinds How can we understand this process of incorporation? It of information in our built environment. In what ways will the appears that symbiotic incorporation of biological processes is mind-brain function differently as it becomes increasingly more quite common in nature. Recent studies offer more evidence incorporated in its milieu, relying on it for information storage that early cells acquired mitochondria by, at some point, and processing? incorporating external organisms into their own cell structure Now let’s talk about Funes. His inability to forget his memories (Thrash et al., 2011; Ferla et al., 2013). Mitochondria have their may seem familiar to some, a metaphor for our current condition. own genome, which is similar to that of bacteria. What was We may now recognize a bit of ourselves in him: we don’t see once a competitor and possibly a parasite became absorbed limits in our capacity to store new information, and the sheer into the organism – and yet, the mitochondrion was not availability of it is sometimes overwhelming. Even without the fully incorporated and retains many of its own processes arrival of the Information Age, we carry with us through life a of self-organization and memory storage, separate from the heavy load of disappointments, broken dreams, little tragedies cell it resides in. This evolutionary process highlights the and many memories. We know that forgetting is a must and a way by which external properties may become incorporated challenge. Yet, we are learning rapidly how to incorporate and into the internal, changing both. Looking at natural and use the massive amounts of data now available to us. The main biological processes of incorporation can help us think challenge for each of us is to harness and control the unleashed of how incorporation of internal and external memory powers given to us by technology. The future is uncertain, but occurs in cognition. some things remain the same. As Kandel (2007, p. 10) wrote, “We are who we are in great measure because of what we learn, and what we remember.” IMPLICATIONS This extended definition of memory may seem ludicrous and AUTHOR CONTRIBUTIONS hard to accept. You may be tempted to throw up your hands and go back to the old, restricted, definition of memory – one that GZ and AV drafted and edited the manuscript. Both authors requires the transmission of subjective memories. contributed to manuscript revision, read, and approved the We beg you not to. There are several benefits of this submitted version. approach to memory. First, in biology, expanding the definition of memory helps us shift from a focus on “experience” (which suggests an immaterial event) to a more material phenomenon: ACKNOWLEDGMENTS a deposit of events that may be stored and used afterward. By expanding the concept of memory, the study of memory The authors wish to thank Michael Lifshitz, Ph.D. for reading an within molecular neurobiology becomes more relevant and early copy of this article and providing feedback. The authors also important. This expanded definition is in large part already wish to thank Steven J. Lynn, Alan M. Rapoport, and Morgan widely accepted, for example, in Kandel’s Aplysia, conditioning Craig for the feedback and encouragement. Frontiers in Psychology | www.frontiersin.org 4 November 2019 | Volume 10 | Article 2523 fpsyg-10-02523 November 5, 2019 Time: 17:15 # 5 Zlotnik and Vansintjan Memory: An Extended Definition Klosin, A., Casas, E., Hidalgo-Carcedo, C., Vavouri, T., and Lehner, B. (2017). 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