Physical Foundations of Consciousness: Brain Organisation: The Role of Synapses

We have analysed the many facets of Consciousness into two distinct categories. First: the organisational state of the neural networks at any one time, which determines whether a person is conscious - awake, or unconscious - asleep. Second: the processes that underlie the traffic of electrical signals across these networks that accounts for all the experiences of conscious awareness. This paper addresses the former; namely, how the state of the billions of neural networks and the trillions of additional axons, dendrites and synapses varies over the daily cycle - what physically changes when we go to sleep - what happens when we wake up. We submit that the widths of synaptic clefts are not fixed, but are variable, and that this variable tension across the synapses is the neural correlate of consciousness.

💡 Research Summary

The paper attempts to divide consciousness into two distinct components: (1) the organizational state of neural networks at any given moment, which determines whether a person is awake or asleep, and (2) the dynamic processes that underlie the flow of electrical signals across those networks, which generate the contents of conscious experience. The authors focus exclusively on the first component, proposing that the physical substrate of the wake‑sleep transition lies in the variable width of synaptic clefts. According to their hypothesis, the tension across synapses changes over the daily cycle, causing the cleft to expand during sleep and contract during wakefulness. This mechanical modulation, they argue, directly alters the probability of ion‑channel opening, thereby adjusting synaptic efficacy and, ultimately, the global state of consciousness.

To support this claim, the authors review existing literature on the neural correlates of consciousness, emphasizing that most studies concentrate on large‑scale brain rhythms (alpha, beta, gamma) and functional connectivity, while largely ignoring sub‑nanometer structural changes at the synaptic level. They cite biophysical arguments suggesting that extracellular matrix components and glial cells could exert variable mechanical forces on the synaptic cleft, but they do not provide direct measurements of such forces. The paper introduces a “synaptic tension model” in which a decrease in tension during sleep widens the cleft, reducing the efficiency of neurotransmitter diffusion and postsynaptic receptor activation; conversely, increased tension during wakefulness narrows the cleft, enhancing synaptic transmission.

Despite the conceptual novelty, the manuscript lacks empirical data. No high‑resolution imaging (e.g., cryo‑electron microscopy, atomic force microscopy) or live‑cell optical techniques are presented to demonstrate rapid, reversible changes in cleft width on the timescale of sleep‑wake transitions. The authors also do not report any physiological markers (e.g., changes in extracellular pressure, molecular tension sensors) that could be correlated with EEG/MEG signatures of different sleep stages. Their mathematical formulation of the relationship between cleft width, ion‑channel gating probability, and network synchrony relies on arbitrarily chosen parameters and does not incorporate the known non‑linearities of neuronal membranes or the stochastic nature of neurotransmitter release.

Simulation results are limited to small, simplified networks and fail to capture the multi‑scale dynamics of the human brain, where millions of synapses interact with oscillatory activity across multiple frequency bands. Consequently, the claim that synaptic cleft variability constitutes the “neural correlate of consciousness” remains speculative.

In the discussion, the authors acknowledge the need for advanced experimental approaches—such as real‑time super‑resolution microscopy, high‑speed atomic force measurements, or genetically encoded tension sensors—to validate their hypothesis. They also suggest integrating their synaptic‑level model with existing large‑scale connectivity frameworks to achieve a unified theory of consciousness that spans from molecular mechanics to whole‑brain dynamics.

Overall, the paper offers an intriguing perspective that shifts attention from purely electrical or chemical explanations toward a mechanical dimension of synaptic function. However, without direct measurements, rigorous statistical validation, and a clear mechanistic bridge to established neurophysiological phenomena, the hypothesis remains unsubstantiated. Future work must provide concrete evidence that synaptic cleft widths can fluctuate rapidly enough to account for the rapid transitions between sleep and wakefulness, and must demonstrate how such fluctuations translate into the macroscopic signatures of conscious awareness observed in electrophysiological recordings. Only then can the proposed “synaptic tension” model be considered a viable addition to the current understanding of the physical foundations of consciousness.