Online research in philosophy

LTP is thought to be an experimental model for studying the cellular mechanism of learning and memory. Shors & Matzel review some contradictory data concerning the linkage between LTP and memory and suggest that LTP does not underlie learning and memory. LTP is a cellular and synaptic process and cannot be a memory mechanism. In fact, it is a cellular information storage mechanism.

It is argued that John Bickle’s Ruthless Reductionism is flawed as an account of the practice of neuroscience. Examples from genetics and linguistics suggest, first, that not every mind-brain link or gene-phenotype link qualifies as a reduction or as a complete explanation, and, second, that the higher (psychological) level of analysis is not likely to disappear as neuroscience progresses. The most plausible picture of the evolving sciences of the mind-brain seems a patchwork of multiple connections and partial explanations, linking anatomy, mechanisms and functions across different domains, levels, and grain sizes. Bickle’s claim that only the molecular level provides genuine explanations, and higher level concepts are just heuristics that will soon be redundant, is thus rejected. In addition, it is argued that Bickle’s recasting of philosophy of science as metascience explicating empirical practices, ignores an essential role for philosophy in reflecting upon criteria for reduction and explanation. Many interesting and complex issues remain to be investigated for the philosophy of science, and in particular the nature of interlevel links found in empirical research requires sophisticated philosophical analysis.

In several places, John Bickle claims that current neuroscientific practice provides actual cellular/molecular reductions of certain mental states. He gives the case study of ‘memory consolidation switch’ as an example where recent findings suggest that this mental state/process can be reduced to the molecular ‘cAMP, PKA, CREB Pathway’. Taking this example, Bickle ‘waves the eleminativist flag’ by claiming that psychological explanations loose their pertinence (or, as he says, ‘became otiose’) once a cellular/molecular explanation replaces them. On this paper I’ll try to show that, even if a reductive explanation of ‘memory consolidation switch’ is disposable, we cannot eschew reductively its causal/functional integrity, i.e.: the explanatory/causal context that defines the mental concept/process ‘memory consolidation switch’ in the first place.

It is argued that John Bickle’s Ruthless Reductionism is flawed as an account of the practice of neuroscience. Examples from genetics and linguistics suggest, first, that not every mind-brain link or gene-phenotype link qualifies as a reduction or as a complete explanation, and, second, that the higher (psychological) level of analysis is not likely to disappear as neuroscience progresses. The most plausible picture of the evolving sciences of the mind-brain seems a patchwork of multiple connections and partial explanations, linking anatomy, mechanisms and functions across different domains, levels, and grain sizes. Bickle’s claim that only the molecular level provides genuine explanations, and higher level concepts are just heuristics that will soon be redundant, is thus rejected. In addition, it is argued that Bickle’s recasting of philosophy of science as metascience explicating empirical practices, ignores an essential role for philosophy in reflecting upon criteria for reduction and explanation. Many interesting and complex issues remain to be investigated for the philosophy of science, and in particular the nature of interlevel links found in empirical research requires sophisticated philosophical analysis.

Recent evidence from our lab indicates that LTP shares an important property with memory consolidation: it is consolidated by natural reinforcement. Nevertheless, the hypothesis, that LTP-like mechanisms or other forms of enhanced synaptic efficacy are basic elements in learning is not unequivocally supported. Skepticism aside, LTP is an accessible experimental model that is optimally equipped for the investigation of the cellular and molecular machinery involved in synaptic weight changes.

Insights into the role of sleep in the molecular mechanisms of memory consolidation may come from studies of activity-dependent synaptic plasticity, such as long-term potentiation (LTP). This commentary posits a specific contribution of sleep to LTP stabilization, in which mRNA transported to dendrites during wakefulness is translated during sleep. Brain-derived neurotrophic factor may drive the translation of newly transported and resident mRNA.

John Bickle's new book on philosophy and neuroscience is aptly subtitled 'a ruthlessly reductive account'. His 'new wave metascience' is a massive attack on the relative autonomy that psychology enjoyed until recently, and goes even beyond his previous (Bickle, J. (1998). Psychoneural reduction: The new wave. Cambridge, MA: MIT Press.) new wave reductionsism. Reduction of functional psychology to (cognitive) neuroscience is no longer ruthless enough; we should now look rather to cellular or molecular neuroscience at the lowest possible level for explanations of memory, consciousness and attention. Bickle presents a fascinating set of experimental cases of such molecule-to-mind explanations. This book qualifies as a showcase of naturalism in the philosophy of mind. Naturally, many of the traditional conceptual approaches in the philosophy of mind are given short shrift, but - in Bickle's metascientific scheme - the role of philosophy of science also seems reduced to explicating laboratory findings. The present reviewers think that this reductionism suffers from overstretching; in particular, the idea of 'explanation in a single bound' from molecule to mind is a bit too ruthless. Still, Bickle's arguments are worth serious attention.

Neurophysiological research suggests our mental life is related to the cellular processes of particular nerves. In the spirit of Occam’s razor, some authors take these connections as reductions of psychological terms and kinds to molecular- biological mechanisms and patterns. Bickle’s ‘intervene cellularly/molecularly and track behaviourally’ reduction is one example of this. Here the mental is being reduced to the physical in two steps. The first is, through genetically altered mammals, to causally alter activity of particular nerve cells, i.e. neurons, at the molecular level and then, under controlled experimental conditions, to use generally-accepted rules of behaviour within psychology to monitor the results of these manipulations. In this article, we argue that Bickle’s case example for molecular reduction, i.e. the reduction of long-term memory to its cellular-molecular mechanisms, cannot support his claims, because it turns out that his chosen molecular pathway is neither a sufficient nor a necessary condition for the memory consolidation switch, and thus, instead of rejecting the multiple realization argument, Bickle’s argument actually speaks in favour of it. Therefore the idea of reductive connections between our mental life and the activity of particular nerves is, at present, still more fiction than reality.

This book precis describes the motives behind my recent attempt to bring to bear “ruthlessly reductive” results from cellular and molecular neuroscience onto issues in the philosophy of mind. Since readers of this journal will probably be most interested in results addressing features of conscious experience, I highlight these most prominently. My main challenge is that philosophers (even scientifically-inspired ones) are missing the nature and scope of reductionism in contemporary neuroscience by focusing exclusively on higher-level cognitive neuroscience, and ignoring the discipline's cell-physiological and molecular-biological core.

The structuralist program has developed a useful metascientific resource: ontological reductive links (ORLs) between the constituents of the potential models of reduced and reducing theories. This resource was developed initially to overcome an objection to structuralist ``global'' accounts of the intertheoretic reduction relation. But it also illuminates the way that concepts at a higher level of scientific investigation (e.g., cognitive psychology) become ``structured through reduction'' to lower-level investigations (e.g., cellular/molecular neuroscience). After (briefly) explaining this structuralist background, I demonstrate how this resource illuminates an actual, emerging scientific example: the link between the psychological concept of a ``consolidation switch'' from short-term to long-term memory and the cellular/molecular mechanisms of the transition from early- to late-phases of long-term potentiation (LTP) (an important type of synaptic plasticity in mammalian hippocampus and cortex).