Identifying content-invariant neural signatures of perceptual vividness

Abstract

Some experiences are stronger than others: they have greater phenomenal magnitude. Although the phenomenal magnitude of experience is a familiar component of human consciousness, the computational scheme underpinning its encoding in the brain is unknown. In particular, it is unknown whether phenomenal magnitude is encoded in a "rich" manner, via the strengthening or broadcast of content-specific perceptual representations, or a "sparse" scheme, in which a content-invariant signal monitors the reliability or precision of first-order contents. In a reanalysis of existing MEG and fMRI data from two distinct studies, we operationalise phenomenal magnitude as subjective ratings of awareness and visibility to address this question. We find that phenomenal magnitude is associated with content-invariant neural signatures distributed across visual, parietal, and frontal cortices. Moreover, we show that these neural signatures exhibit similarities with other analogue magnitude codes such as number, with each rating being represented as being more similar to its neighbours, and less similar to more distant ratings. Our findings suggest a role for a content-invariant analogue magnitude code in determining the strength of perceptual experience.

Vividness of Visual Imagery Supported by Intrinsic Structural-Functional Brain Network Dynamics

“…One avenue for future research could be exploring how the brain’s network structures uniquely support vivid visual imagery as opposed to processing awareness of external visual stimuli and identifying the shared and distinctly neural mechanisms that underlie these forms of conscious experiences (Barnett et al, 2024). Studies indicate a complex interplay in brain networks during conscious experiences.…”

Creating something out of nothing: Symbolic and non-symbolic representations of numerical zero in the human brain

“…We note however that the neural responses recorded in our study to empty-set stimuli were still within the context of a numerical taskand, as such, our results are specific to the concept of numerical absence and do not provide a direct test of a link between numerical zero and sensory absence. Out study offers a path towards a formal test of this hypothesis in future work -for instance, investigating relationships between numerical absence and nonnumerical perceptual absences 40,62,64 .…”