A structural constraint on neural correlates of consciousness

Distinguishing neural correlates that are genuinely tied to conscious experience from those that are merely coincidental requires a principled approach. The authors propose neurophenomenal structuralism, which relies on the fact that phenomenal experiences form structures of similarity and difference. By using these structures to individuate experiences in neuroscience and psychophysics, they derive a structural similarity constraint: a neural activation must preserve the structure of the associated phenomenal domain to qualify as a neural correlate of consciousness proper. An example from Brouwer and Heeger illustrates the constraint. This approach aims to refine the search for neural correlates by filtering out merely statistical associations.

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Abstract

Researchers on the neural correlates of consciousness (NCC) need to distinguish mere statistical NCCs from NCCs proper. Some neural events may be co-occurrent, probabilistically coupled, or coincidental with a type of conscious experience but lack any deeper connection to it, while in other cases, the relation between neural states and a type of experience hints at a strong metaphysical relation, which distinguishes such NCCs proper from mere statistical NCCs. In order to address this issue of how to distinguish NCCs proper from mere statistical NCCs, we propose a position we call neurophenomenal structuralism. The position hinges on the uncontroversial idea that phenomenal experiences relate to each other in degrees of similarity and difference. These complex structures are used to identify and individuate experiences in the methods of neuroscience, psychophysics, and phenomenology. Such individuation by structure leads to phenomenal holism, which has implications for how to investigate consciousness neuroscientifically and generates a constraint by which we can distinguish NCCs proper from mere statistical NCCs: the structural similarity constraint. Neural activation must preserve the structure governing the domain of experiences it is associated with in order to count as that domain’s NCC proper. Any activation that fails to preserve phenomenal structure fails to be an NCC proper. We illustrate how this constraint works with a study by Brouwer & Heeger (2009) as an example.