Sleep Mysteries - Making Sense of Vision - Parkinson's Profile - Shrinking Brains

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Breedlove, S

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Oct 15, 2025, 6:27:11 AM (6 days ago) Oct 15

https://aeon.co/essays/two-billion-humans-are-doing-something-bizarre-right-now-sleeping

What sleep is

Vladyslav Vyazovskiy

After decades of research, there is still no clearly articulated scientific consensus on what sleep is or why it exists. Yet whenever sleep comes up as a topic of discussion, it is quickly reduced to its necessity and importance. Popular media remind us of what can, and will, go wrong if we do not sleep enough, and serve up some handy tips on how to overcome insomnia. Discussed exclusively in utilitarian terms, we are force-fed the idea that sleep exists solely for our immediate benefit. Is this really all we ever want to know about a third of our existence? Sleep is perhaps the biggest blind spot, or the longest blind stretch, if you will, of our life. Naturally, the health and societal implications of sleep are huge: from technogenic disasters caused by tiredness, to sleep deprivation as a form of torture or weapon of war, and to sleep disorders, some of which inflict so much suffering that they compete with chronic pain. However, in my opinion, to say sleep is important is to miss the point entirely. Sleep is the single most bizarre experience that happens to all of us, against our will, every day.

The disconnect between old questions about sleep that have remained open for centuries and new, increasingly sophisticated technologies applied to solve them is ever growing. The predominant view is that sleep provides some sort of restoration for the brain or the body: what goes awry – out of balance – in waking is almost magically recalibrated by sleep. At the centre of this narrative is the individual-who-sleeps, a lone castaway, locked in a permanent, inexorable cycle of sleeping and waking, without hope of breaking free (except in death). From the moment of opening one’s eyes, the clock starts ticking, and there is a price to pay for every minute of wakeful time, measured precisely in proportion to the transgression of staying awake. Like a snake eating its own tail, waking and sleep consume each other in an endless cycle, without beginning or end. There is no mercy, and lack of sleep can be paid back only by sleep. The image of burning a candle at both ends endures.

Despite vast technological advances in recent years, exponential growth in our understanding of nature and the cosmos, and major breakthroughs in biology and medicine, there is still no unified theory of sleep. I find myself pondering whether it is time to step back and seek a different angle.
Medieval manuscript illustration depicting people sleeping in three beds, with two standing figures in dialogue beside them, and an ornate floral border.

https://www.thetransmitter.org/the-big-picture/the-visual-systems-lingering-mystery-connecting-neural-activity-and-perception/

The visual system’s lingering mystery: Connecting neural activity and perception

By Grace Lindsay

Neuroscientists have spent decades characterizing the types of information represented in the visual system. In some of the earliest studies, scientists recorded neural activity in anesthetized animals passively viewing stimuli—a setup that led to some of the most famous findings in visual neuroscience, including the discovery of orientation tuning by David Hubel and Torsten Wiesel.

But passive viewing, whether while awake or anesthetized, sidesteps one of the more intriguing questions for vision scientists: How does the rest of the brain use this visual information? Arguably, the main reason for painstakingly characterizing the information in the visual system is to understand how that information drives intelligent behavior. Connecting the dots between how visual neurons respond to incoming stimuli and how that information is “read out” by other brain regions has proven nontrivial. It is not clear that we have the necessary experimental and computational tools at present to fully characterize this process. To get a sense for what it might take, I asked 10 neuroscientists what experimental and conceptual methods they think we’re missing.

Decoding is a common approach for understanding the information present in the visual system and how it might be used. But decoding on its own—training classifiers to read out prespecified information about a visual stimulus from neural activity patterns—cannot tell us how the brain uses information to perform a task. This is because the decoders we use for data analysis do not necessarily match the downstream processes implemented by neural circuits. Indeed, there are pieces of information that can reliably be read out from the visual system but aren’t accessible to participants during tasks. Primary visual cortex contains information about the ocular origin of a stimulus, for example, but participants are not able to accurately report this information.

https://www.nytimes.com/interactive/2025/10/13/us/sue-goldie-parkinsons.html

Sue Goldie Has Parkinson’s Disease

By John Branch Photographs by Sophie Park

It starts with a tingle, a tremor, a sense that something is off.

Dr. Sue Goldie doesn’t recognize the symptoms at first. Maybe she ignores them, wishes them away.

It is 2021. She is 59, in the prime of a long teaching career at Harvard. She has just immersed herself in the sport of triathlon.

One coach notes something off with her running cadence. Another wonders why her left arm isn’t fully lifting out of the water. A trainer sees a slight tremor. The first time Sue races, she feels a strange vibration, like an internal tremble.

Then Sue sees it herself: Twitching fingers on her left hand.

Tests reveal it is Parkinson’s, the incurable neurological disease that robs its victims of their motor skills, and sometimes their minds, one extinguished neuron at a time. Parkinson’s doesn’t always alter life spans, but it always upends lives.

The diagnosis elicits a storm of emotions, but also raises questions, both pragmatic and deep, that have consumed Sue since.

At what point, if ever, do I have to say something? Who needs to know? What do I reveal and what do I conceal?

And, most profoundly: Does a diagnosis have to be an identity?

For nearly four years, she keeps her diagnosis from most Harvard administrators, colleagues and students, worried about what it will do to her reputation. She grows more comfortable revealing herself away from work, in the world of triathlon.

“I feel very strongly that I should be able to disclose this when I want, how I want, and it’s under my control,” she tells me last year. But Parkinson’s does not wait.

Maybe others don’t notice the physical signs, not yet. They don’t see her in the early morning, shuffling off-balance to the bathroom before her medications kick in, a daily reminder that Parkinson’s was not something she dreamed last night.

Maybe they don’t see the pill boxes in her purse, the exposed feeling she gets when the dopamine medications wear off, the persistent worry behind her cheerful disposition.

Her symptoms are worsening. Disguising them is exhausting.

Starting today, she is Sue with Parkinson’s.

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https://www.nature.com/articles/d41586-025-03353-5

Men’s brains shrink faster than women’s: what that means for Alzheimer’s

Rachel Fieldhouse

During ageing, men experience a greater reduction in volume across more regions of the brain than women do, according to a longitudinal study published today in the Proceedings of the National Academy of Sciences1. The authors suggest this means that age-related brain changes do not explain why women are more frequently diagnosed with Alzheimer’s disease than men are.

“It’s really important that we understand what happens in the healthy brain so that we can better understand what happens when people get these neurodegenerative conditions,” says Fiona Kumfor, a clinical neuropsychologist at the University of Sydney, Australia. This study adds to scientists’ understanding of typical brain ageing, she adds.

Nearly twice as many women are diagnosed with Alzheimer’s disease as men, and ageing is the biggest risk factor for the disease. This has prompted research into age-related sex differences in the brain. “If women’s brains declined more, that could have helped explain their higher Alzheimer’s prevalence,” says co-author Anne Ravndal, a PhD student at the University of Oslo.

Previous research investigating sex differences in brain ageing has shown mixed results, Ravndal adds. Several studies have found that men experience greater loss of total grey matter and hippocampus size compared with women, whereas other work has reported a sharper decline of grey matter in women.
Brain scans

The latest study included more than 12,500 magnetic resonance imaging (MRI) brain scans from 4,726 people — at least two scans per person, taken an average of three years apart — who did not have Alzheimer’s disease or any cognitive impairments and were control participants in 14 larger data sets. The researchers compared how the individuals’ brain structures changed over time, looking at factors including the thickness of grey matter and the size of areas that are associated with Alzheimer’s disease, such as the hippocampus, which is essential to memory.