The demise of the synapse as the locus of memory: A looming paradigm shift?

Abstract

Synaptic plasticity is widely considered to be the neurobiological basis of learning and memory by neuroscientists and researchers in adjacent fields, though diverging opinions are increasingly being recognized. From the perspective of what we might call "classical cognitive science" it has always been understood that the mind/brain is to be considered a computational-representational system. Proponents of the information-processing approach to cognitive science have long been critical of connectionist or network approaches to (neuro-)cognitive architecture, pointing to the shortcomings of the associative psychology that underlies Hebbian learning as well as to the fact that synapses are practically unfit to implement symbols. Recent work on memory has been adding fuel to the fire and current findings in neuroscience now provide first tentative neurobiological evidence for the cognitive scientists' doubts about the synapse as the (sole) locus of memory in the brain. This paper briefly considers the history and appeal of synaptic plasticity as a memory mechanism, followed by a summary of the cognitive scientists' objections regarding these assertions. Next, a variety of tentative neuroscientific evidence that appears to substantiate questioning the idea of the synapse as the locus of memory is presented. On this basis, a novel way of thinking about the role of synaptic plasticity in learning and memory is proposed.

Special Issue “On Defining Artificial Intelligence”—Commentaries and Author’s Response

“…Some neuroscientists are now investigating sub-neural computations for other reasons, e.g. Trettenbrein (2016); Grant (2018). Perhaps 22nd Century (or later) AI system will use mechanisms that are now unimaginable: one of the themes of the Turing-inspired "Meta-morphogenesis" project.…”

Terminological and Epistemological Issues in Current Memory Research

“…Then, there are active forgetting (Hardt et al, 2013;Davis and Zhong, 2017) and retrieval (Hardt et al, 2010) that substantially alter the presumably consolidated changes in synaptic strength of long-term memory representations in a process of reactivation-induced plasticity (Box 2) (Nader and Hardt, 2009). Thus, dormant or in use, the neurobiological "substrate" of memory resembles a fluid more than a solid, always ready to "morph" into new configurations, and yet long-lasting memories are possible despite the constant turnovers and fluctuations of this presumed substrate (Trettenbrein, 2016). This primary quality, the fundamentally plasmic nature of the "memory substrate, " is not at all reflected in terms like engram or consolidation (Box 2).…”

Varieties Of Evolved Forms Of Consciousness, Including Mathematical Consciousness

“…Some psychologists make the mistake of thinking that reliably repeatable laboratory experiments and observations, possibly enhanced using brain-scanning technology, can answer all questions, thereby ignoring most of the evolutionary and developmental history, and the mostly sub-microscopic (especially sub-neural, and more generally sub-cellular) mechanisms and processes that are difficult or impossible to observe directly. Grant [ 26 ] and Trettenbrein [ 27 ] are among the neuroscientists who now counter this trend. The variety and depth of investigations into sub-neural mechanisms that challenge widely-held assumptions about consciousness and related phenomena (including action control and ontology extension) may expand enormously in future, partly because our understanding of questions to ask increases and partly because our technology for detecting, observing, measuring and interacting with sub-microscopic processes increases.…”

“…. Collaborators would be very welcome, including researchers working on the many varieties of consciousness in non-human organisms, and the explanatory powers of sub-neural forms of chemical computation, discussed in References [ 26 , 27 ], among others.…”