Somatosensory Stability - Vision & Culture - Alzheimer's & Fatty Acids - Antidepresants

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Aug 23, 2025, 7:41:09 AMAug 23

https://www.thetransmitter.org/plasticity/adult-human-cortex-does-not-reorganize-after-amputation/

Adult human cortex does not reorganize after amputation

By Angie Voyles Askham

The adult cortex can rewire itself after injury, according to a series of classic experiments. When a monkey loses sensory input from a finger, for example, the region of the somatosensory cortex dedicated to that finger becomes overrun by inputs from the animal’s nearby fingers or face; the cortical map for the unused finger fades, and nearby maps of other body parts expand.

“This is what I read in my textbook. This is what the lecturers told me in my lectures in university,” says Tamar Makin, professor of cognitive neuroscience at the University of Cambridge.

But—contrary to those classic findings—such large-scale cortical reorganization did not happen in three people who lost an arm, according to a new functional imaging study Makin and her colleagues published today in Nature Neuroscience. Instead, the somatosensory map of each person’s hands, feet and lips, generated when they moved or attempted to move that body part, remained stable in the years before and after their hand was removed.

“The representation of the hand persists,” says Makin, who led the study.

The work is the first longitudinal look at whether amputation changes that cortical mapping. The results confirm what previous cross-sectional studies have hinted at, and they should put an end to the debate about how readily the adult cortex can shift its function, Makin says.

But not everyone agrees. The study is an important contribution to the field, and it shows that maps of somatosensation driven by motor input remain stable after amputation, says Ben Godde, professor of neuroscience at Constructor University, who was not involved in the new work or the classic experiments. But that does not mean that other cortical maps are not shifting as a result of changing inputs, he says. “It’s not evidence that there’s no plasticity.”

https://www.scientificamerican.com/article/does-culture-change-visual-perception-debunking-the-carpentered-world/

Why a Classic Psychology Theory about Vision Has Fallen Apart

By Nora Bradford

During her training in anthropology, Dorsa Amir, now at Duke University, became fascinated with the Müller-Lyer illusion. The illusion is simple: one long horizontal line is flanked by arrowheads on either side. Whether the arrowheads are pointing inward or outward dramatically changes the perceived length of the line—people tend to see it as longer when the arrowheads point in and as shorter when they point out.
Graphic shows how the Müller-Lyer illusion makes two equal-length lines seem to have different lengths because of arrowlike tips pointing inward or outward.

Most intriguingly, psychologists in the 1960s had apparently discovered something remarkable about the illusion: only European and American urbanites fell for the trick. The illusion worked less well, or didn’t work at all, on groups surveyed across Africa and the Philippines.

The idea that this simple illusion supposedly only worked in some cultures but not others compelled Amir, who now studies how culture shapes the mind. “I always thought it was so cool, right, that this basic thing that you think is just so obvious is the type of thing that might vary across cultures,” Amir says.

But this foundational research—and the hypothesis that arose to explain it, called the “carpentered-world” hypothesis—is now widely disputed, including by Amir herself. This has left researchers like her questioning what we can truly know about how culture shapes how we see the world.

When researcher Marshall Segall and his colleagues conducted the cross-cultural experiment on the Müller-Lyer illusion in the 1960s, they came up with a hypothesis to explain the strange results: difference in building styles. The researchers theorized that the prevalence of carpentry features, such as rectangular spaces and right angles, trained the visual systems of people in more wealthy, industrialized cultures to perceive these angles in a way that make them more prone to the Müller-Lyer illusion.

https://www.theguardian.com/science/2025/aug/20/women-with-alzheimers-have-unusually-low-omega-fatty-acid-levels-study-finds

Women with Alzheimer’s have unusually low omega fatty acid levels

Ian Sample Science editor

Women should ensure they are getting enough omega fatty acids in their diets according to researchers, who found unusually low levels of the compounds in female patients with Alzheimer’s disease.

The advice follows an analysis of blood samples from Alzheimer’s patients and healthy individuals, which revealed levels of unsaturated fats, such as those containing omega fatty acids, were up to 20% lower in women with the disease.

The low levels were not seen in men with Alzheimer’s, suggesting there may be sex differences in how the disease takes hold and affects a person’s physiology.

“The difference between the sexes was the most shocking and unexpected finding,” said Dr Cristina Legido-Quigley, a senior author on the study at King’s College London published in the Alzheimer’s & Dementia journal. “There’s an indication that having less of these compounds could be causal in Alzheimer’s, but we need a clinical trial to confirm that.”

Alzheimer’s disease is twice as common in women as in men. Factors including women’s longer average lifespan, differences in hormones, immune responses and educational opportunities can all play a role in the development of the disease.

In the latest study, researchers analysed the levels of lipids, which are fatty compounds, in the blood of 306 people with Alzheimer’s, 165 people with mild cognitive impairment and 370 people who were cognitively healthy controls. Lipids can be saturated or unsaturated, with the former generally considered unhealthy and the latter broadly healthy.

https://undark.org/2025/08/21/opinion-antidepressant-trap/

Asking the Wrong Questions About Antidepressants

By Eric Reinhart

A recent study in the journal JAMA Psychiatry claims to offer reassuring news to hundreds of millions of people who are taking, or considering taking, antidepressants: Withdrawal from the medications, it said, is usually mild and below the threshold for clinical significance. The analysis, which drew on data from more than 17,000 patients, was quickly picked up by international news outlets. Critics responded just as quickly, calling it misleading and dismissive of real-world suffering.

As both a practicing psychiatrist and critic of the harms inadvertently inflicted by my own field, I fear we’re having the wrong debate — again.
Conceptual image of an orange seesaw with a pink brain and an oversized pill balancing on it, could illustrate ideas around ssri, anti-depressants, headache pills and other medication for mental and brain health

Every few years, another study or media exposé reignites controversy over these drugs: How effective are they really? Are withdrawal symptoms real or imagined? Are antidepressants harming people more than they help? These questions, while important, are stuck inside the narrow terms set by a medication-centric psychiatric industry, even when criticizing it. They flatten the experience of patients and ignore the intersecting role of clinicians, families, institutions, media, culture, and public policy in shaping both suffering and relief, trapping us in circular debates and deflecting attention from other ways of understanding and addressing what ails us.

Yes, antidepressant withdrawal is real. Yes, some people suffer greatly while trying to come off these drugs, with withdrawal risk varying among different kinds of antidepressants. I have also seen many patients appear to benefit greatly from such medications. But when we focus only on the biology of response and withdrawal, or treat psychiatric medications as purely pharmacologic agents whose harms and benefits can be definitively measured and settled by clinical trials, we obscure the more complex — and far more consequential — dynamics by which these medications affect self-perception, social relationships, and political life.

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https://www.npr.org/2025/08/21/nx-s1-5507165/light-pollution-bird-day-hour-longer

Artificial light has essentially lengthened birds' day

Nell Greenfieldboyce

The early bird gets the worm, as the old saying goes. And now a lot of birds around the globe are starting their days earlier than ever, because of unnaturally bright skies caused by light pollution.

"For these birds, effectively their day is almost an hour longer. They start vocalizing about 20 minutes earlier in the morning and they stop vocalizing about 30 minutes later in the evening," says Neil Gilbert, a wildlife ecologist with Oklahoma State University.

That's the conclusion of a sweeping study that analyzed bird calls from over 500 bird species in multiple continents, giving researchers an unprecedented look at how human-created lights are affecting the daily lives of birds worldwide.

Scientists already knew that light pollution affects birds. It can send migrating birds off course, and some observations have linked artificial lighting to unusual bird activity, including one recent report of American Robins feeding their babies in their nest at night.

But Gilbert and Brent Pease, with Southern Illinois University, took a more comprehensive view, by analyzing millions of recordings of birdsong.

The audio was collected by thousands of devices installed in backyards and other locations, mostly by birdwatchers and other wildlife enthusiasts, as part of a program called BirdWeather. The BirdWeather devices automatically register bird calls and use them to identify the species, mostly to let bird fans know what's flitting through their yards.