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acid andy [soylentnews.org] writes:

Researchers for the Human Brain Project [humanbrainproject.eu] have published [frontiersin.org] a theory about how we become conscious of a sensory stimulus, which has been likened to a surfer timing when to catch a wave. [humanbrainproject.eu]

When a sensory stimulus reaches our brain, it doesn’t drop in calm waters - brains are always agitated with spontaneous activity. Like a surfer, the stimulus has to catch the right wave of activity at the right time to emerge into consciousness. Right in between two waves is the perfect time to do so, argue Giovanni Rabuffo and Pierpaolo Sorrentino of the Human Brain Project.

We know from extensive experiments that the brain can perceive sensory stimuli even when we are not aware of them: while some information reaches the ‘consciousness threshold’, other simply does not, even given comparable incoming stimuli.

[...]How come the same stimulus reaches consciousness in certain moments, and fails to do so in others? As this stimulus is the same, it must depend on something changing in the brain.
[...] In recent years, neuroimaging has shown that ‘becoming aware of a stimulus’ comes with a burst of activations that spread across the brain. However, similar such bursts spontaneously stretch across the brain at all times, even in the absence of stimuli. These bursts are often referred to as ‘neuronal avalanches’', borrowing the concept of avalanches from statistical mechanics. And we experience these spontaneous avalanches during rest, while we are typically conscious. Is there a way to unify conscious perception, spontaneous brain activity, and neuronal avalanches?

The activation of a neuron and the consequent widespread effects across the brain might be approached with the same methods for studying the spread of a wildfire through a forest, or the compression waves traveling during an earthquake.

Or a rough sea. Surfing is popular in Marseille, so the metaphor comes up naturally for the researchers. Imagine you are a surfer that wants to ride the next wave. If you wait until the apex of the wave has reached you, you are already too late, it will pass you by. You need to start moving before that, in the interval between two waves. “We posit that something similar is happening to sensory signals reaching the brain,” says Sorrentino. “The signal is the surfer, and the spontaneous neuronal avalanches are the waves. If the signal reaches the brain at the same time as one of the bursts reaches its peak, the brain would be too busy to notice, and it’s less likely that the signal will reach consciousness. In the former scenario, the information is collected, but not experienced. But if the signal arrives before that, it will ride the incoming wave and be more likely to be perceived consciously.” This would account for the aforementioned ‘failure of ignition’ that happens seemingly at random: the two signals were the same but only one was able to catch a favorable wave, at the right time and place.

Rabuffo and Sorrentino haven’t put their hypothesis to test with their proposed experiment yet, but they expect it to work. If confirmed, the hypothesis could solve ongoing conundrums in both consciousness and critical thresholds, bridging gaps in the theoretical neuroscience landscape.

Reference: Giovanni Rabuffo, Pierpaolo Sorrentino, Christophe Bernard and Viktor Jirsa, Spontaneous neuronal avalanches as a correlate of access consciousness, Frontiers Psychology, doi.org/10.3389/fpsyg.2022.1008407

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