memoria y conciencia

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Brain and Cognition 42, 2022 (2000)

doi:10.1006/brcg.1999.1150, available online at http://www.idealibrary.com on

Memory, Consciousness, and the Brain

Gianfranco Dalla Barba

U. 324 INSERM, Paris, France; and Hopital Henri Mondor, Creteil, France

The end of the second millennium has coincided with significant progressin the understanding of human memory. Since the late 1950s, modern neuro-

psychological research has provided a considerable amount of data concern-ing the relation between mnesic phenomena and their neural correlates.Based on clinical and experimental observations, new concepts have beenintroduced and old concepts have been reformulated. Implicit expression ofknowledge, or implicit memory (Milner, 1958; Warrington & Weiskrantz,1968), short-term memory and working memory (Baddeley & Hitch, 1974),the distinction between semantic and episodic memory, among others, arenow widely accepted notions. Indeed the very idea that memory is not a

unitary system but one that reflects rather the interaction of different memorysystems or of different memory processes probably represents the greatestachievement of the past fifty years of neuropsychological research onmemory.

However, the progress in the understanding of memory phenomena ledto the flourishing of a number of theories and models of memory whichalmost invariably contain both an omission and a paradox. It is clear that

any theory of memory must contain a presupposition concerning the pastand its nature, since memory by definition is memory of the past. However,you can read paper after paper or book after book without finding any directdiscussion or even assumption on what should be one of the very concernsin theories of memory, i.e. the nature of the past and how this is representedin our brains. The result of this omission is the paradox of the memory traceof which many theories of memory are victim.

An assumption common to many old and new theories on memory is that

of considering a memory as the result of the preservation of the past in theorganism which remembers. Accordingly, if I now perceive an event or ob-

Address correspondence and reprint requests to Gianfranco Dalla Barba, M.D., Ph.D., U.324 INSERM, Centre Paul Broca, 2 ter, rue dAlesia, 75014 Paris, France. E-mail: [email protected].

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0278-2626/00 $35.00Copyright 2000 by Academic Press

All rights of reproduction in any form reserved.


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ject, for example the keyboard on which I am typing, tomorrow I will beable to remember it because this image has, so to speak, been deposited insome part of my brain in the form of a memory trace. The activation of thetrace, that is, its subsequent passage from a passive to an active state, will

result in recollection of the event. It is easy to see that any theory whichbases the possibility of recollection on the preservation of an event inside atrace contains a paradox, fruit of a misleading assumption. The misleadingassumption on which these theories are based consists in believing that timecan exist in things. But it should have been clear that things as such arenot temporal. As such, the objects of the world are neither present, nor past,nor future, but they acquire a temporal dimension only in the presence ofan agent who goes to the trouble of making them temporal. The erroneousassumption on which theories of memory are founded is directly reflectedin the paradox to which these theories fall victim. The paradox of the memorytrace consists in seeing memory as originating in elements borrowed fromthe present. Let us see why.

The event that I now perceive, for example, the keyboard on the tablein front of me, is without doubt a present event. This event determines amodification in the equilibrium of a system, be it physical (the nervous sys-

tem) or virtual (the computational level), which I call memory trace. Whatis the temporal nature of the modification which the event produces in thesystem, namely of the memory trace? Its nature is certainly present. Thekeyboard which I now perceive is present and if one accepts that this eventproduces a modification somewhere, one will have to accept that said modi-fication will be present, and that the event represented by that modificationwill also be present. What happens when that event contained in the traceis recollected in memory? When the event is recollected it happens in thepresent, that is, as the result of the reactivation of the modification that theevent caused on a physiological, biochemical, neuroanatomical, neurociber-netical, or functional level. And so it is not at all clear how memory, whosebasic characteristic is memory of the past, can stem from a combination ofpresent phenomena, perception, the conservation of the trace, and recollec-tion. Activation of the memory trace should, if anything, coincide with anew perception of the event contained within the trace, not with its memory

since the event contained in the trace was present as it ended up in the traceand continued to be so for as long as it remained enclosed in the trace. If,on the other hand, I recognize that particular event as past, this happensbecause I attribute a precise meaning to it, that of being past, a meaningwhich by definition cannot be contained in the trace since, in every momentof its existence, it has never ceased to be present. This does not mean thatevents do not cause modifications in our brain or in our cognitive system,but these modifications cannot be used to explain recollection.

So, if the past, the very concrete essence of memory, can by no meansbe contained in a memory trace, how do we explain that memories are possi-


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ble and, more specifically, how do we explain that episodic memories, i.e.,the conscious recollection of an episode as past, are possible? It seems thatat this point a new problem arises, the problem of consciousness. In fact, ifconsciousness of the past, i.e., episodic remembering, cannot be only the

result of the activation of the memory trace itself, consciousness itself mustcontribute to generating the past. Indeed, consciousness of the past can beconsidered as a specific and original mode of consciousness, a mode in whichconsciousness addresses its object in a temporal, past framework (DallaBarba, in press). Although some preliminary evidence in favor of this hy-pothesis is available (Dalla Barba, Cappelletti, Signorini, & Denes, 1997),future research will clarify the role of consciousness in mental life, its rela-tion to memory and, possibly, its neural correlates. In order to achieve thisgoal we will need both a coherent and articulated concept of consciousness,and new paradigms which make possible the direct study of consciousnessand of its relation to memory. One of such paradigms has already been pro-posed (Tulving, 1985). Based on what could be named experimental phe-nomenology, this paradigm has been successfully used in a considerablenumber of studies. Contingent to its development and, in general, to thedevelopment of experimental phenomenology in a near future, the relation

between memory and consciousness will increasingly become a scientificproblem and consciousness will be no longer the philosophers joy and thescientists nightmare (Tulving, 1993).

REFERENCES

Baddeley, A., & Hitch, G. J. 1974. Working memory. In G. Bower (Ed.), Recent advancesin learning and motivation, (Vol. 8, pp. 4790). New York: Academic Press.

Dalla Barba, G. (in press). Memory, consciousness and temporality: What is retrieved andwho exactly is controlling the retrieval? In E. Tulving (Ed.), Memory, consciousness,and the brain: The Tallinn Conference. Philadelphia: The Psychology Press.

Dalla Barba, G., Cappelletti, Y. J., Signorini, M., & Denes, G. 1997. Confabulation: Remem-bering another past, planning another future. Neurocase, 3, 425436.

Milner, B. 1958. Psychological defects produced by temporal lobe excision. Research Publica-tionsAssociation for Research in Nervous and Mental Disease, 36, 244257.

Tulving, E. 1985. Memory and consciousness. Canadian Psychology, 26, 112.

Tulving, E. 1993. Varieties of consciousness and levels of awareness in memory. In A. Badde-ley & L. Weiskrantz (Eds.), Attention: Selection, awareness and control (pp. 282299).New York: Oxford University Press.

Warrington, E., & Weiskrantz, L. 1968. A new method of testing of long-term retention withspecial reference to amnesic patients. Nature, 217, 972974.

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