Attention and capacity limits in perception: A cellular metabolism account, Bruckmaier et al, 2020

Indigophoton · Aug 4, 2020

Saw this, thought of us. I'm not up to reading the paper (abstract and link below), so haven't assessed its quality, but the article in neuroscience news is interesting. Perhaps this sort of phenomenon might help to explain why an ME brain is particularly prone to falling over with too much incoming stimuli, or too much to attend to, and why mental processing can be so exhausting, since we have less energy (presumably) to begin with.

Energy Demands Limit Our Brains’ Information Processing Capacity

August 3, 2020
Summary: Paying attention alters how the brain allocates its limited energy. As the brain uses more energy to process information we attend to, the less energy is supplied to processing outside our field of attention.

Source: UCL

Our brains have an upper limit on how much they can process at once due to a constant but limited energy supply, according to a new UCL study using a brain imaging method that measures cellular metabolism.

The study, published in the Journal of Neuroscience, found that paying attention can change how the brain allocates its limited energy; as the brain uses more energy in processing what we attend to, less energy is supplied to processing outside our attention focus.

Explaining the research, senior author Professor Nilli Lavie (UCL Institute of Cognitive Neuroscience) said: “It takes a lot of energy to run the human brain. We know that the brain constantly uses around 20% of our metabolic energy, even while we rest our mind, and yet it’s widely believed that this constant but limited supply of energy does not increase when there is more for our mind to process.

“If there’s a hard limit on energy supply to the brain, we suspected that the brain may handle challenging tasks by diverting energy away from other functions, and prioritising the focus of our attention.

......

The research team of cognitive neuroscientists and biomedical engineers measured cerebral metabolism with a non-invasive optical imaging method. In this way they could see how much energy brain regions use as people focus attention on a task, and how that changes when the task becomes more mentally demanding. They used broadband near-infrared spectroscopy to measure the oxidation levels of an enzyme involved in energy metabolism in brain cells’ mitochondria, the energy generators that power each cell’s biochemical reactions.

.....

Professor Lavie said: “In this way, we have managed to connect people’s experience of brain overload to what’s going on inside their neurons, as high energy demands for one purpose are balanced out by reduced energy use related to any other purpose. If we try to process too much information we may feel the strain of overload because of the hard limit on our brain capacity.

https://neurosciencenews.com/energy-information-processing-16756/.
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Paper - Journal of Neuroscience 3 August 2020, JN-RM-2368-19; DOI: https://doi.org/10.1523/JNEUROSCI.2368-19.2020

Abstract
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Limits on perceptual capacity result in various phenomena of inattentional blindness. Here we propose a neurophysiological account attributing these perceptual capacity limits directly to limits on cerebral cellular metabolism. We hypothesized that overall cerebral energy supply remains constant, irrespective of mental task demand, and therefore an attention mechanism is required to regulate cellular metabolism levels in line with task demands. Increased perceptual load in a task (imposing a greater demand on neural computations) should thus result in increased metabolism underlying attended processing, and reduced metabolism mediating unattended processing. We tested this prediction measuring oxidation states of cytochrome c oxidase (oxCCO), an intracellular marker of cellular metabolism. Broadband near-infrared spectroscopy was used to record oxCCO levels from human visual cortex while participants (both sexes) performed a rapid sequential visual search task under either high perceptual load (complex feature-conjunction search) or low load (feature pop-out search). A task-irrelevant, peripheral checkerboard was presented on a random half of trials. Our findings showed that oxCCO levels in visual cortex regions responsive to the attended-task stimuli were increased in high versus low perceptual load, while oxCCO levels related to unattended processing were significantly reduced. A negative temporal correlation of these load effects further supported our metabolism trade-off account. These results demonstrate an attentional compensation mechanism that regulates cellular metabolism levels according to processing demands. Moreover, they provide novel evidence for the widely-held stipulation that overall cerebral metabolism levels remain constant irrespective of mental task demand and establish a neurophysiological account for capacity limits in perception.

Significance Statement

We investigated whether capacity limits in perception can be explained by the effects of attention on the allocation of limited cellular metabolic energy for perceptual processing. We measured the oxidation state of cytochrome c oxidase, an intracellular measure of metabolism, in human visual cortex during task performance. The results showed increased levels of cellular metabolism associated with attended processing and reduced levels of metabolism underlying unattended processing when the task was more demanding. A temporal correlation between these effects supported an attention-directed metabolism trade-off. These findings support an account for inattentional blindness grounded in cellular biochemistry. They also provide novel evidence for the claim that cerebral processing is limited by a constant energy supply, which thus requires attentional regulation.
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Binkie4 · Aug 4, 2020

Good to see you here @Indigophoton.

I'm not up to reading the paper either.
I do however try to limit how many things might be competing for my attention at any one time. Life is impossible otherwise.

alktipping · Aug 5, 2020

just stating the bloody obvious . having m.e for thirty years i am well aware of how higher processes give way to the autonomic functions of the brain . simply put thinking on your feet is way harder when you barely have the energy to function .

Invisible Woman · Aug 5, 2020

I've skimmed it.

Nice to see the problem being analysed from this angle as opposed to......

you are focussing on your symptoms and this is distracting you......

You are subconsciously trying to get out of dealing with whatever....

Makes a change from the usual guff.

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Attention and capacity limits in perception: A cellular metabolism account, Bruckmaier et al, 2020

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