The minimal neural correlate of the conscious state, regardless of the neural activity correlated with the ever-changing contents of experience, has still not been identified. Different attempts have been made, mainly by comparing the normal waking state to seemingly unconscious states, such as deep sleep or general anesthesia. A more direct approach would be the neuroscientific investigation of conscious states that are experienced as free of any specific phenomenal content. Here we present serendipitous data on content-free awareness (CFA) during an EEG-fMRI assessment reported by an extraordinarily qualified meditator with over 50,000 h of practice. We focused on two specific cortical networks related to external and internal awareness, i.e., the dorsal attention network (DAN) and the default mode network (DMN), to explore the neural correlates of this experience. The combination of high-resolution EEG and ultrafast fMRI enabled us to analyze the dynamic aspects of fMRI connectivity informed by EEG power analysis. The neural correlates of CFA were characterized by a sharp decrease in alpha power and an increase in theta power as well as increases in functional connectivity in the DAN and decreases in the posterior DMN. We interpret these findings as correlates of a top-down-initiated attentional state excluding external sensory stimuli and internal mentation from conscious experience. We conclude that the investigation of states of CFA could provide valuable input for new methodological and conceptual approaches in the search for the minimal neural correlate of consciousness.

It has been repeatedly shown that specific brain activity related to planning movement develops before the conscious intention to act. This empirical finding strongly challenges the notion of free will. Here, we demonstrate that in the Libet experiment, spontaneous fluctuations of the slow electro-cortical potentials (SCPs) account for a significant fraction of the readiness potential (RP). The individual potential shifts preceding self-initiated movements were classified as showing a negative or positive shift. The negative and positive potential shifts were analyzed in a self-initiated movement condition and in a no-movement condition. Comparing the potential shifts between both conditions, we observed no differences in the early part of the potential. This reveals that the apparently negative RP emerges through an unequal ratio of negative and positive potential shifts. These results suggest that ongoing negative shifts of the SCPs facilitate self-initiated movement but are not related to processes underlying preparation or decision to act.

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A philosopher and a cognitive neuroscientist conversed with Buddhist lama Tilmann Lhündrup Borghardt (TLB) about the unresolved phenomenological concerns and logical questions surrounding “pure” consciousness or minimal phenomenal experience (MPE), a quasi-contentless, non-dual state whose phenomenology of “emptiness” is often described in terms of the phenomenal quality of luminosity that experienced meditators have reported occurs in deep meditative states. Here, we present the excerpts of the conversation that relate to the question of how it is possible to first have and later retrieve such non-dual states of selflessness and timelessness that are unrelated to sensory input. According to TLB, a “pure” experience of consciousness contains the phenomenal quality of luminous clarity, which is experienced solely in the transitional phase from the non-dual state of absolute emptiness to the state of minimal emptiness, when the person gradually returns to duality. However, this quality of luminous clarity can also be experienced in non-minimal states as in the experiential mode of being awakened. TLB describes this transition as a kind of ephemeral afterglow in the form of a maximally abstract phenomenal quality, i.e., luminosity, which justifies the conclusion of having been in a state of “pure” consciousness.