John Bickle

In their review essay (published in this issue), Looren de Jong and Schouten take my 2003 book to task for (among other things) neglecting to keep up with the latest developments in my favorite scientific case study (memory consolidation). They claim that these developments have been guided by psychological theorizing and have replaced neurobiology's traditional 'static' view of consolidation with a 'dynamic' alternative. This shows that my 'essential but entirely heuristic' treatment of higher-level cognitive theorizing is a mistaken view of actual scientific practice. In response I contend that, on the contrary, a closer look at the memory reconsolidation following reactivation experiments and data suggests (1) a less revolutionary judgment about the proposed alternative, and (2) a now-complete reliance on ruthlessly reductive experimental methods from cellular and molecular neuroscience. These conclusions save the heuristic status I propose for higher-level investigations of behavior and brain. I close with a brief comment on their further charge that I 'sell out' philosophy of science to factual developments in science itself.

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).

Psychoneural reduction is under attack again, only this time from a former ally: cognitive neuroscience. It has become popular to think of the brain as a complex system whose theoretically important properties emerge from dynamic, non-linear interactions between its component parts. ``Emergence'' is supposed to replace reduction: the latter is thought to be incapable of explaining the brain qua complex system. Rather than engage this issue at the level of theories of reduction versus theories of emergence, I here emphasize a role that reductionism plays – and will continue to play – even if neuroscience adopts this ``complex systems'' view. In detailed investigations into the function of complex neural circuits, certain questions can only be addressed by moving down levels and scales. This role for reduction also finds a place for approaches that dominate mainstream neuroscience, like the widespread use of experimental techniques and theories from molecular biology and biochemistry. These are difficult to reconcile with the anti-reductionist sentiments of the ``complex systems'' branch of cognitive neuroscience.

Many believe that phenomenology is an uneasy fit with the notion that consciousness is simply produced by physical manipulations. This chapter takes one of the most provocative examples of this type of manipulation — cortical microstimulation leading to seemingly random conscious states such as the image of one's grandmother or a musical melody — and shows that such phenomena are not only consistent with Husserlian phenomenology, but actually underscore the importance of Husserl's careful distinctions. It guards against conflating ‘physical’ with ‘empirically observable’ by falling into the natural attitude and unwarrantedly equating the ‘perceived object’ with the corresponding ‘physical object’ that supposedly causes the perception, and then equating both of those with the ‘intentional’ object. There can be an intentional object with no physical object, and subserved only by a physical brain event. But this does not detract from the intentional meaning of the object-as-experienced. In this kind of example, it shows more clearly than ever Husserl's distinction between the noesis and the noema within each intentional experience.

The previous decade has seen renewed critical interest in the multiple realization argument. These criticisms constitute a "second wave" of challenges to this central argument in late-20th century philosophy of mind. Unlike the first wave, which challenged the premise that multiple realization is inconsistent with reduction or type identity, this second wave challenges the truth of the multiple realization premise itself. Since psychoneural reductionism was prominent among the explicit targets of the multiple realization argument, one might think that this second wave of challenges provides important aid and comfort to reductionists. In this paper, however, I provide reasons for thinking it does not. This is not to the detriment of psychoneural reductionism because, as I also argue here, and unrecognized by the current non-reductive orthodoxy in philosophy of mind, one key argument among the first wave of criticisms of the multiple realization argument has never been adequately rejoined.

Structuralism provides useful resources for advancing our understanding of the intertheoretic reduction relation and its place in the history of science. This paper begins by surveying these resources and assessing their metascientific significance. Nevertheless, important challenges remain. I close by arguing that the reductionism implicit in current scientific practice in a paradigmatic reductionistic scientific field –“molecular and cellular cognition”– is better understood on an “intervene and track” model rather than as any kind of intertheoretic relation. I illustrate my alternative model by describing briefly a recent reductionistic result from the field. It appears doubtful that any structuralist resources will illuminate this newly-recognized type of reduction-in-actual-scientific-practice.

Although great progress in neuroanatomy and physiology has occurred lately, we still cannot go directly to those levels to discover the neural mechanisms of higher cognition and consciousness. But we can use neurocomputational methods based on these details to push this project forward. Here we describe vector subtraction as an operation that computes sequential paths through high-dimensional vector spaces. Vector-space interpretations of network activity patterns are a fruitful resource in recent computational neuroscience. Vector subtraction also appears to be implemented neurally in primate frontal eye field activity, which computes dimensions of saccadic eye movements. We use this apparent neural implementation as a model and construct from it a general neurocomputational account of an important type of sequential cognitive and conscious process. We defend the biological plausibility of all components of the general model and show that it yields testable anatomical and physiological predictions. We close by suggesting some interesting consequences for consciousness if our model characterizes correctly the neural mechanisms producing a common type of episode in our conscious streams.

As opposed to the dismissive attitude toward reductionism that is popular in current philosophy of mind, a “ruthless reductionism” is alive and thriving in “molecular and cellular cognition”—a field of research within cellular and molecular neuroscience, the current mainstream of the discipline. Basic experimental practices and emerging results from this field imply that two common assertions by philosophers and cognitive scientists are false: (1) that we do not know much about how the brain works, and (2) that lower-level neuroscience cannot explain cognition and complex behavior directly. These experimental practices involve intervening directly with molecular components of sub-cellular and gene expression pathways in neurons and then measuring specific behaviors. These behaviors are tracked using tests that are widely accepted by experimental psychologists to study the psychological phenomenon at issue (e.g., memory, attention, and perception). Here I illustrate these practices and their importance for explanation and reduction in current mainstream neuroscience by describing recent work on social recognition memory in mammals.