Why can some people easily stop eating when they are full and others can't, which can lead to obesity?
A Northwestern Medicine study has found one reason may be a newly discovered structural connection between two regions in the brain that appears to be involved in regulating feeding behavior. These regions involve the sense of smell and behavior motivation.
The weaker the connection between these two brain regions, the higher a person's Body Mass Index (BMI), the Northwestern scientists report.
The investigators discovered this connection between the olfactory tubercle, an olfactory cortical region, which is part of the brain's reward system, and a midbrain region called the periaqueductal gray (PAG), involved in motivated behavior in response to negative feelings like pain and threat and potentially in suppression of eating.
The study will be published May 16 in the Journal of Neuroscience.
Previous research at Northwestern by co-author Thorsten Kahnt, now at the National Institutes of Health, has shown the smell of food is appetizing when you're hungry. But the smell is less appealing when you eat that food until you are full.
Odors play an important role in guiding motivated behaviors such as food intake, and-; in turn -; olfactory perception is modulated by how hungry we are.
Scientists have not fully understood the neural underpinnings of how the sense of smell contributes to how much we eat. The desire to eat is related to how appealing the smell of food is -; food smells better when you are hungry than when you are full. But if the brain circuits that help guide this behavior are disrupted, these signals may get confused, leading to food being rewarding even when you are full. If this happens, a person's BMI could increase. And that is what we found. When the structural connection between these two brain regions is weaker, a person's BMI is higher, on average."
Guangyu Zhou, corresponding author, research assistant professor of neurology at Northwestern University Feinberg School of Medicine
Though this study does not directly show it, the study authors hypothesize that healthy brain networks connecting reward areas with behavior areas could regulate eating behavior by sending messages telling the individual that eating doesn't feel good anymore when they're full. In fact, it feels bad to overeat. It's like a switch in the brain that turns off the desire to eat.
But people with weak or disrupted circuits connecting these areas may not get these stop signals, and may keep eating even when they aren't hungry, the scientists said. Related StoriesCOVID-19 survivors show lasting brain function alterations, fMRI study findsCan virtual reality be the future of brain health? New research suggests VR exercise enhances working memoryStudy uncovers sex differences in brain responses to low sexual desire
"Understanding how these basic processes work in the brain is an important prerequisite to future work that can lead to treatments for overeating," said senior author Christina Zelano, associate professor of neurology at Feinberg. How the study worked
This study used MRI brain data -; neurological imaging -; from the Human Connectome Project, a large multi-center NIH project designed to build a network map of the human brain.
Northwestern's Zhou found correlations to BMI in the circuit between the olfactory tubercle and the midbrain region, the periaqueductal gray. For the first time in humans, Zhou also mapped the strength of the circuit across the olfactory tubercle, then replicated these findings in a smaller MRI brain dataset that scientists collected in their lab at Northwestern.
"Future studies will be needed to uncover the exact mechanisms in the brain that regulate eating behavior," Zelano said.
The research reported in this press release was supported by the National Institute on Deafness and Other Communication Diseases grants R01-DC-016364, R01-DC-018539, R01-DC-015426 and the Intramural Research Program at the National Institute on Drug Abuse grant ZIA DA000642, all of the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Source:
Northwestern UniversityJournal reference:
Zhou, G., et al. (2024) Structural connectivity between olfactory tubercle and ventrolateral periaqueductal gray implicated in human feeding behavior. Journal of Neuroscience. doi.org/10.1523/JNEUROSCI.2342-23.2024.
Cardinals have failed to reach the required two-thirds majority in their first vote to choose a new pope in the Vatican.
Black smoke emerged from the Sistine Chapel chimney at 8pm, indicating they had been unable to agree.
Crowds in St Peter’s Square had been kept waiting longer than expected and most were hoping for the white smoke that signals the arrival of a new pontiff.
Image: People in St Peter’s Square as black smoke emerged from the Sistine Chapel. Pic: Reuters
There was only one vote today, but from Thursday the 133 cardinals will hold two votes in the morning and two in the afternoon until at least 89 pick the same name.
The conclave started on Wednesday afternoon after cardinals swore an oath of secrecy and the doors of the Sistine Chapel were shut to the outside world.
They have given up their phones and are cut off from the outside world until a new pope is chosen.
The most recent conclaves – for Pope Francis in 2013, Pope Benedict XVI in 2005 and Pope John Paul II in 1978 – all lasted less than three days.
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Doors close as conclave begins
The voting takes places beneath Michelangelo’s legendary frescoes and the chapel – normally a packed tourist site – has installed tight security.
It’s been swept for listening devices, signal jammers have been installed, and its windows have been covered to protect from spy drones.
Lead seals have also been put on 80 doors at the conclave site to stop people going in and out.
The cardinals will sleep and eat at the Casa Santa Marta, a guest house within the Vatican where Pope Francis lived, until the process is over.
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1:01
What happens during a conclave?
Image: The cardinals are voting in the splendour of the Sistine Chapel
They cardinals began Wednesday by taking mass, before a solemn two-by-two procession into the Sistine Chapel in the afternoon.
Dresses in their red garb, they chanted the Litany of the Saints and Veni Creator – a hymn imploring the saints to help them find a new leader.
They then each came forward to take an oath of secrecy, placing a hand on the gospel and also promising not to allow any outside influence.
The final piece of theatre was the Latin declaration “Extra omnes” (“everyone else out”) and Archbishop Diego Ravelli, an aide to the late pope, pushed the the doors shut.
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0:27
Cardinal wishes Pope frontrunner ‘double best wishes’
Conclave is beginning 16 days after Pope Francis’s death, which came after a long hospital stay with pneumonia.
Many experts believe it will come down to a choice between someone who will continue his progressive approach and a more conservative candidate.
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1:02
Conclave: Behind the scenes
Image: The temporary stove where cardinals will burn their ballots. Pic: AP
Among the favourites is Luis Tagle, a cardinal who could become the first Asian pontiff, and who’s been likened to Pope Francis.
Two Italians are also seen as strong contenders: The Archbishop of Bologna, Matteo Zuppi, and the so-called “deputy pope” Pietro Parolin.
The pope’s identity is normally revealed soon after the white smoke emerges, when he steps onto the balcony to wave to the crowds in St Peter’s Square.
A senior Labour MP has said the government needs to take “corrective action” over planned disability benefit cuts – as Sir Keir Starmer faces a growing backbench rebellion.
Tan Dhesi, chair of the influential Commons defence committee, told the Politics Hub with Sophy Ridge the “disappointing” local election results show the government must listen and learn, particularly over welfare reforms.
The government has proposed tightening the eligibility requirements for the personal independent payment, known as PIP.
A claimant must score a minimum of four points on one PIP daily living activity, such as preparing food, washing and bathing, using the toilet or reading, to receive the daily living element of the benefit.
Mr Dhesi, the MP for Slough, said “corrective action” needs to be taken but insisted if the government changed tact, it would not be a U-turn as the disability cuts were only proposals.
Image: Tan Dhesi spoke to Sky’s Sophy Ridge
“A government which is in listening mode should be looking at what the electorate is saying,” he said.
“And we need to make sure that it’s our moral duty, responsibility, to look after the most vulnerable within our community, whether that’s in Slough, whether that’s elsewhere across the country.
“So, I hope that the government will be taking on board that feedback and many of us as MPs are giving that feedback in various meetings happening here in Westminster and then we need to take corrective action.”
Image: Alex Davies-Jones said the government was seeking to ‘protect the vulnerable’
Minister Alex Davies-Jones told the Politics Hub a Labour government “will always seek to protect the most vulnerable” and it wants to “listen to people who have got real lived experience”.
She added she has the “utmost respect for Tan, he’s a great constituency MP and he’s doing exactly what he should be doing, is representing his constituency”.
Sir Keir is facing a rebellion from Labour MPs, with about 40 in the Red Wall – Labour’s traditional heartlands in the north of England – reposting a statement on social media in which they said the leadership’s response to the local elections had “fallen on deaf ears”.
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8:27
Starmer defends winter fuel cuts
Several backbench Labour MPs also spoke out against the plans during a debate on PIP and disabled people in parliament on Wednesday.
Ian Byrne, MP for Liverpool West Derby, said he would “swim through vomit to vote against” the proposed changes and said: “This is not what the Labour Party was formed to do.”
Bell Ribeiro-Addy, the MP for Clapham and Brixton Hill, said she feared tightening PIP eligibility would cause deaths, adding: “Lest we forget that study that attributed 330,000 excess deaths in Britain between 2012 and 2019 to the last round of austerity cuts [under the Conservative government].”
Diane Abbott, the longest-serving female MP, accused the government of putting forward “contradictory arguments”.
“On the one hand, they insist they are helping the disabled by putting them back to work,” she said.
“But on the other hand, they say this cut will save £9bn. Well, you can’t do both.”
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1:23
‘I’ll struggle if I lose disability support’
However, fellow Labour MP David Pinto-Duschinsky, said MPs cannot “ignore this issue” of health-related benefit claimant figures rising at “twice the rate of underlying health conditions”.
Responding for the government, social security minister Sir Stephen Timms said PIP claims were set to “more than double, from two million to over 4.3 million this decade”.
“It would certainly not be in the interests of people currently claiming the benefits for the government to bury its head in the sand over that rate of increase,” he added.
A man whose dismembered body was found in a suitcase had raped and blackmailed a teenager, a court has heard.
The remains of Albert Alfonso, 62, and Paul Longworth, 71, were found in a suitcase and trunk which had been left near the Clifton Suspension Bridge in Bristol in July 2024.
Yostin Mosquera is on trial at the Old Bailey in London accused of murdering and dismembering Mr Alfonso and Mr Longworth.
The 35-year-old denies both murders but has admitted the manslaughter of Mr Alfonso.
A witness, giving evidence under the pseudonym James Smith, appeared at the trial by video link on Wednesday.
Mr Smith said he met Mr Alfonso nearly 20 years ago when he was around 17 or 18 and had gone to his flat for drinks.
He said he remembered drinking heavily and then waking up with a “banging headache”.
“I said to him, ‘what’s happened?’ – he showed me a video of me on all fours and he was penetrating me,” he told the court.
“I didn’t know what to do. I was mortified. At this point, I didn’t know my sexuality – I was confused and scared.”
He said Mr Alfonso told him if he did “favours”, the video would never be shared.
Under cross-examination, defence barrister Tom Little KC asked: “Does it cross your mind, looking back, that you were raped?”
“Now, yes,” Mr Smith replied.
“And does it cross your mind that your drink may have been spiked?”, the barrister asked.
“Now, yes,” the witness responded.
“Does it cross your mind that you were groomed by Albert Alfonso?”, Mr Little asked.
“Now, yes,” Mr Smith said.
After the alleged incident, the two met regularly, with Mr Alfonso paying Mr Smith around £150 for each sexual encounter, the court heard.
During the COVID pandemic, the witness said he became closer with Mr Alfonso and began spending time with Mr Longworth.
Mr Smith told the court he was later introduced to Mosquera.
Image: Yostin Mosquera is on trial at the Old Bailey. Pic: Metropolitan Police/PA
He said the relationship between Mosquera and Mr Alfonso was “good – very good”.
“I didn’t see anything that seemed like they disliked each other,” he added.
He described Mr Longworth as someone who “wouldn’t hurt a fly”.