How to test whether brain organoids possess consciousness

Ruhr-University Bochum

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Lucia Melloni heads the Predictive Brain Department at Ruhr University Bochum and is a member of the University Alliance Ruhr’s Research Center One Health Ruhr.

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Credit: RUB, Marquard

The development of brain organoids is advancing at a breakneck pace. Researchers are creating tiny cell clusters in the lab that behave like fragments of the human brain. Whether such organoids could develop intelligence—or even consciousness—remains a matter of debate. Professor Lucia Melloni of Ruhr University Bochum, Germany, and Professor Stanislas Dehaene of the Collège de France in Paris propose an experimental framework to answer this question. Their article appeared in a special issue on brain organoids of the journal Neuron on November 11, 2026.

“I don’t believe that brain organoids currently possess consciousness,” says Lucia Melloni, who conducts research at Ruhr University Bochum and at the Research Center One Health Ruhr within the University Alliance Ruhr. “But given the pace with which the technology is advancing, they may do so in future. That’s why we need to start thinking about how we can find out.” Melloni and Dehaene have developed an experimental approach to do just that.

What organoids are and what they are capable of

Organoids are grown from human pluripotent stem cells. Through specific chemical treatments, they differentiate into tiny cell clusters in a petri dish that behave, for example, like specific brain regions, the heart, or the gut. Researchers have already shown that human organoids can be implanted into mouse embryos, where they form connections with the embryo.

Different types of organoids can be coupled into assembloids in order to study their interactions. For instance, one group reconstructed a pain signaling pathway by coupling four organoids; they demonstrated that the assembloid reacted to capsaicin, the active compound in chili peppers.

Neural correlates of mind and consciousness

“A reaction, however, is not proof that the tissue feels anything,” Lucia Melloni clarifies. “To address the question of whether tissue could develop a mind—or even consciousness—we first asked what cognitive computations underlie the behavior of adult humans, particularly behaviors we associate with consciousness.”

Imagine a person repeatedly hearing a sequence of syllables: ba-ba-ba-ba-bu, ba-ba-ba-ba-bu, and so on. They quickly detect the difference between ba and bu, a pattern that requires no conscious processing. Over time, however, they can learn the full pattern i.e., that four ba syllables are followed by a bu syllable. If, after several repetitions, they hear the sequence ba-ba-ba-ba-ba, they consciously perk up because the expected bu is missing.

Electrical stimulation tests with organoids

Comparable tests could also be performed on organoids: Researchers could stimulate the tissue with different sequences of electrical signals and measure its electrical response. This would reveal whether an organoid, too, reacts to the absence of an expected stimulus.

Melloni and Dehaene propose eight tests using different stimulation sequences that require varying degrees of complex neural processing; some of these processes are typically associated with consciousness. “If an organoid were to respond to several of these tests in a certain way,” Melloni explains, “that would be evidence that it has developed something akin to a mind—or even consciousness.”

Engaging all stakeholders

The Bochum neuroscientist anticipates groundbreaking insights from organoid research in the future. “For example, in curing certain diseases and in understanding how the human body responds to climate change,” she elaborates. Together with colleagues, she advocates for the establishment of an international board to regulate organoid research. “The goal must be to gain knowledge and cure diseases in an ethically responsible way—involving the society,” Melloni says. A first step towards a debate with all relevant actors was taken at the Asilomar Conference in California in 2025, which Lucia Melloni attended.

Engaging all relevant stakeholders is also the approach of the Ruhr Innovation Lab, a consortium of Ruhr University Bochum and TU Dortmund University that will be funded as a Consortium of Excellence starting January 1, 2027. Melloni is a member of the Ruhr Innovation Lab’s potential area “The Healthy Mind in a Complex World”.

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Journal

Neuron

DOI

10.1016/j.neuron.2026.10.009

Article Title

Cognitive Evaluation of Brain Organoids and Assembloids

Article Publication Date

11-Nov-2026

 

Rare soil bacteria help steady microbial networks across China’s Loess Plateau

Maximum Academic Press

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Taxonomic composition and phylogenetic patterns of core, abundant, and rare subcommunities.

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Credit: Agricultural Ecology and Environment

A research team has found that core bacteria and rare bacteria play roles in shaping soil microbial communities across China's Loess Plateau. Core bacteria were most strongly associated with the complexity of bacterial networks, while rare bacteria were particularly important for their stability. The groups also responded differently to environmental conditions: climate was the main influence on core and abundant bacteria, whereas soil properties mattered more for rare bacteria. These findings could help guide soil biodiversity monitoring and ecological restoration by identifying microbial groups associated with community organization and resilience.

Soil bacteria support nutrient cycling, organic matter decomposition, and other processes. Researchers distinguish between abundant, rare, and widely distributed core microorganisms to understand how these communities respond to environmental change. Studies have revealed different distribution patterns among these groups, but their assembly mechanisms and contributions to community complexity and stability remain uncertain. China's Loess Plateau, where rainfall declines from southeast to northwest and vegetation spans forests, shrublands, and grasslands, provides an opportunity to investigate how bacterial communities form across contrasting environments.

A study (DOI: 10.48130/aee-0026-0020) published in Agricultural Ecology and Environment on 28 August 2026 by Xing Wang's & Xinhui Han's team, Northwest A&F University, reports that core bacterial assembly was dominated by deterministic processes, while stochastic processes predominated among abundant and rare bacteria, with distinct associations linking these groups to network complexity and stability.

The researchers collected 117 surface soil samples across four regions of the Loess Plateau in July 2016, covering ecosystems from primary forests to planted grasslands. Each sample combined ten soil cores from the upper ten centimeters. They measured vegetation characteristics and soil properties, including moisture, pH, texture, and nutrient concentrations, alongside climatic information. Sequencing the bacterial 16S ribosomal RNA gene enabled the team to identify bacterial sequence variants and classify them by abundance. Rare variants had relative abundances below 0.001%, while abundant variants exceeded 0.1%. Core variants, defined independently, occurred in at least 80% of samples and could overlap with abundance categories. The team then compared evolutionary relationships, used null models to assess community assembly, and constructed networks of bacterial co-occurrence. Path modeling and boosted regression trees examined links between environmental conditions, bacterial groups, and network properties. Rare bacteria accounted for 50.02% of sequence variants but only 4.24% of total abundance. Abundant bacteria represented fewer than 1% of variants yet contributed 31.48% of abundance. Core bacteria comprised just 0.34% of variants and accounted for 21.19% of average abundance. Core and abundant groups were more closely related evolutionarily than rare groups. Assembly analyses indicated stronger environmental selection among core bacteria, whereas chance processes predominated in abundant and rare groups. The network contained 9,990 bacterial variants connected by 194,063 associations. Core and abundant bacteria had more connections and occupied more central positions than rare bacteria. Modeling identified the strongest relationship between core bacteria and network complexity, while rare bacteria were particularly associated with stability. Greater network complexity was positively associated with estimated stability. Climate primarily explained variation in core and abundant groups; soil characteristics were more influential for rare groups. Analyses supported these relationships after accounting for spatial environmental patterns, ecosystem type, and vegetation type.

The study highlights why counting the most abundant bacteria alone may overlook microbial groups associated with soil community stability. It provides evidence that widespread core bacteria and diverse rare bacteria contribute complementary information about microbial network organization. Because the findings rely on co-occurrence patterns from surface soils sampled during one growing season, they do not establish direct bacterial interactions or long-term resilience. Sampling deeper soils and tracking seasonal changes could test whether these relationships persist and strengthen their usefulness for ecosystem assessment.

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References

DOI

10.48130/aee-0026-0020

Original Source URL

https://doi.org/10.48130/aee-0026-0020

Funding information

This work was financially supported by the Ningxia Hui Autonomous Region Agricultural Science and Technology Independent Innovation Fund (NYGZ-26-13-02), the Natural Science Foundation Project of Shaanxi Province (2025JC-JCQN-015), the National Natural Science Foundation of China (42477324), and the China Postdoctoral Science Foundation (2025M782750).

About Agricultural Ecology and Environment

Agricultural Ecology and Environment (e-ISSN 3070-0639) is a multidisciplinary platform for communicating advances in fundamental and applied research on the agroecological environment, focusing on the interactions between agroecosystems and the environment. It is dedicated to advancing the understanding of the complex interactions between agricultural practices and ecological systems. The journal aims to provide a comprehensive and cutting-edge forum for researchers, practitioners, policymakers, and stakeholders from diverse fields such as agronomy, ecology, environmental science, soil science, and sustainable development.

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Journal

Agricultural Ecology and Environment

DOI

10.48130/aee-0026-0020

Subject of Research

Not applicable

Article Title

Core and rare microbiota enhance bacterial community complexity and stability along environmental gradients on the Loess Plateau

 

Lipids from banana peels help cherry tomatoes stay fresh longer

Edible coating made from lipid-rich material extracted from discarded banana peels helps in postharvest preservation of cherry tomatoes

Kyushu University

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Banana peel waste can be turned into edible coatings that help cherry tomatoes stay fresh longer. Cherry tomatoes coated with sodium alginate-based films containing different banana peel-derived components were evaluated during storage. The lipid-containing coating showed the strongest preservation performance, reducing weight loss and slowing respiration, ethylene production, softening, and other indicators of postharvest deterioration compared with uncoated tomatoes.

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Credit: Fumihiko Tanaka/Kyushu University

Fukuoka, Japan—Fruits and vegetables keep “breathing” even after they’re picked. Respiration consumes sugars and organic acids that contribute to flavor, while moisture loss and continued ripening soften the fruit. These changes shorten shelf life and contribute to food waste. Thin edible coatings can be applied to regulate gas and water transfer and preserve fresh produce. Now, food scientists are exploring whether by-products we often discard could supply ingredients for these coatings.

In a study published in Food Bioscience on October 1, 2026, a team led by Professor Fumihiko Tanaka and Associate Professor Fumina Tanaka of Kyushu University’s Faculty of Agriculture examined banana peels for this purpose. They added proteins, polysaccharides, or lipids extracted from the peels to an edible coating and compared their effects on cherry tomatoes. The lipid-containing coating was most effective at slowing moisture loss and keeping the tomatoes firm.

“We wanted to turn one source of waste into a way to reduce another,” says Jiao Zeng, the paper’s first author and a PhD student at Kyushu University. “Banana peels account for about a third of the fruit’s weight, yet they are usually discarded despite containing valuable compounds. We explored whether these compounds could help cherry tomatoes stay fresh for longer.”

The researchers extracted proteins, polysaccharides, and lipids from discarded banana peels and added each separately to a coating made from sodium alginate and cinnamaldehyde. Sodium alginate is a substance derived from brown seaweed that forms the coating’s film structure. Cinnamaldehyde, a compound found in cinnamon, contributes antimicrobial activity.

The researchers found that the three components affected the coating in different ways. Polysaccharides helped form a more closely connected network within the coating, while proteins contributed to interactions between its components. Lipids, meanwhile, formed water-repelling regions. Among the tested formulations, the lipid-enriched coating showed the most effective preservation performance.

“Lipids enhanced the hydrophobicity of the coating and significantly improved its moisture-barrier properties, thereby reducing water loss during storage,” explains Fumina Tanaka.

The team then tested the coatings on cherry tomatoes stored at 25 °C. By day 15, uncoated tomatoes suffered over 30% weight loss and visible decay, whereas all coated variants mitigated deterioration. The lipid-based coating performed best, maintaining marketable quality for over 20 days. The researchers also observed lower respiration and reduced ethylene production, which acts as the primary chemical trigger for fruit ripening. Coated tomatoes also showed a slower loss of firmness and less juice leakage.

Sensory tests of appearance, texture, aroma, and taste showed a similar pattern. The uncoated tomatoes fell below the study’s acceptable quality by day 15, while those treated with the lipid coating remained acceptable through day 20. They also maintained higher levels of soluble solids, including sugars that contribute to sweetness.

“Our study revealed how each component contributes to preservation,” notes Fumihiko Tanaka. “We hope to develop this approach further to reduce food loss and support a circular bioeconomy, where agricultural by-products become valuable resources.”

Although the coatings have so far been tested only on cherry tomatoes under specific storage conditions, the findings suggest promise for preserving fresh produce after harvest. The researchers plan to test fruits and vegetables with different ripening and storage characteristics to determine how widely they could apply the approach.

A banana peel’s usefulness could extend beyond the fruit it once protected. That potential may also apply to other agricultural by-products, offering new ingredients for food preservation while reducing waste and environmental impact. With further development, coatings tailored to different types of produce could help maintain quality from farm to market, giving growers and retailers more time to sell their products and consumers more time to enjoy them.

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For more information about this research, see “Fraction-specific regulation of barrier properties and postharvest physiology in alginate/cinnamaldehyde edible coatings incorporating banana peel waste-derived biomolecules for cherry tomato preservation,” Jiao Zeng, Xirui Yan, Fanze Meng, DongHui Luo, Reshaka Kavindi Malawara Arachchige, Saki Ishiko, Fumina Tanaka, and Fumihiko Tanaka, Food Bioscience, https://doi.org/10.1016/j.fbio.2026.109756

About Kyushu University 
Founded in 1911, Kyushu University is one of Japan's leading research-oriented institutions of higher education, consistently ranking as one of the top ten Japanese universities in the Times Higher Education World University Rankings and the QS World Rankings. Located in Fukuoka, on the island of Kyushu—the most southwestern of Japan’s four main islands—Kyushu U sits in a coastal metropolis frequently ranked among the world’s most livable cities and historically known as Japan’s gateway to Asia. Its multiple campuses are home to around 19,000 students and 8,000 faculty and staff. Through its VISION 2030, Kyushu U will “drive social change with integrative knowledge.” By fusing the spectrum of knowledge, from the humanities and arts to engineering and medical sciences, Kyushu U will strengthen its research in the key areas of decarbonization, medicine and health, and environment and food, to tackle society’s most pressing issues.

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Journal

Food Bioscience

DOI

10.1016/j.fbio.2026.109756

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Fraction-specific regulation of barrier properties and postharvest physiology in alginate/cinnamaldehyde edible coatings incorporating banana peel waste-derived biomolecules for cherry tomato preservation

 

'Pink noise' can help revitalize enjoyable conversation

A Dartmouth study shows how good conversation balances the familiar and the unexpected

Dartmouth College

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Dartmouth researchers used the neural-network software behind chatbots such as Claude and ChatGPT to convert nearly 1,700 conversations into a numerical map where similar sentences lived nearby each other and dissimilar snippets farther away. They rendered the distances between them as distinct signals that looked like red, white, or pink noise. Pink noise emerged as a 'Goldilocks signal' between intense red noise and aimless white noise that provides stability with the flexibility to change topics. The dialogue pictured shows the semantic distance in a white-noise conversation where the speakers jump between the two topics—hiking and listening to music—very quickly.

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Credit: Science Advances/AAAS

From bickering with strangers online to politically charged holidays with relatives, many discussions today wind up at loggerheads.

But Dartmouth researchers have found a conversational recipe they call "pink noise" that may help people get back to more enjoyable and engaging interactions, according to a new study in Science Advances.

Pink noise is strongest in conversation that balances the familiar and the unexpected, says Katie O'Nell, the study's first author and a doctoral candidate in psychological and brain sciences. People focus on one subject long enough to learn from each other, then switch to a new topic to keep the conversation fresh, she says.

"We find that conversations exhibiting more pink noise tend to be rated as more enjoyable," O'Nell says. "When people talk about good conversation, they often use metaphors like 'in sync' or 'being on the same wavelength' that break down when we consider them in mathematical terms. We show that over-synchronization is probably a bad thing and that moving both toward and away from each other can help conversationalists feel like they click."

"We're hoping our work opens up more research into how to improve human communication, especially around difficult topics," says Emily Finn, the study's corresponding author and an assistant professor of psychological and brain sciences.

"Our findings suggest that if you've stayed on a topic for long enough that it's feeling tedious, don't be afraid to inject some randomness and search for a new topic together," she says. "If you're bouncing between topics more quickly than you'd like, take a moment to reflect on what your partner is saying and ask follow-up questions." 

The Dartmouth team used transformers—the neural-network software behind chatbots such as Claude and ChatGPT—to convert an open-source dataset of transcripts from nearly 1,700 conversations known as the CANDOR corpus into a numerical map. Each person's turn to talk is its own data point, with similar sentences living nearby each other and dissimilar snippets located farther away.

The researchers then looked at how far away each part of the conversation was from the one before it, rendering these distances as distinct signals similar to a sound wave. They tested whether each signal looked more like red, white, or pink noise. 

These "colors of noise" are part of the noise spectrum, with each having different characteristics. While most people think of noise as an unwelcome interruption like radio static, a signal's noise color simply indicates the relative power of different frequency bands.

Red noise is muffled and low-frequency, like the monotone of a distant ocean, versus the sharp, high-frequency white noise of a television with no signal. Pink noise is like the steady roar of a waterfall and has a consistent sound energy.

Pink noise is evident in many systems that require flexible switching between stability and randomness to function properly, from heartbeats and the coordination of neurons to the coupling of climate systems such as the ocean and the atmosphere.

"I think of pink noise as a 'Goldilocks signal' between red and white noise," Finn says. "Pink noise exists in the middle of these two types of signals, balancing the slow, stable meandering of red noise with the quick, jumpy movements of white noise. It gives you some amount of stability, while also allowing you to make a change when you need to."

On the canvas of a conversation, white-noise dialogue rambles with no particular focus, like a conversation with a toddler, while red-noise conversation is intensely focused and unyielding, like an unfriendly legal deposition, the researchers report in Science Advances.

"We need more empirical work to test which strategies work to introduce more pink noise into conversation, but we suggest that people pay attention to when their conversations feel more red or white," Finn says. 

An example of pink noise could be two people initially talking about sports who have different preferences but find common ground, O'Nell says. One speaker says, "I'm a huge baseball fan," to which the other replies, "I like basketball better myself." The first speaker then replies, "My son does too, it's faster paced," to which the other person says, "Exactly! Does your son play any sports?" 

"They're adapting to each other," O'Nell says. "The second person isn't a fan of basketball but doesn't just dead-end the conversation or move to a different topic. He finds something adjacent in his enjoyment of a different sport that allows the other speaker to find her own connection. He then latches onto the topic of her son to learn more about her since it's clear they're not going to talk about sports teams at length." 

The dataset of conversations the Dartmouth team used to build their numerical map also includes post-conversation surveys. The team reports that the amount of pink noise in a conversation accurately predicted how much people said they enjoyed the exchange and felt connected to the person they talked to.

The team then evaluated transcripts from a speed-dating podcast to better understand the importance of pink noise in real-world conversations. They report that first-date conversations with more pink noise were more likely to lead to a second date.

But pink noise is not just for people born with a knack for conversation, according to the study in Science Advances. An evaluation of 25 podcasts with dual hosts reveals that pink noise increased over the first 50 episodes for nearly all the pairs of speakers. 

"This result is particularly interesting because it suggests that coordinating our words in a way that results in pink noise might be a learnable skill," O'Nell says. "Anyone who's suffered through an awkward conversation on a date or at the Thanksgiving table may have a reason for hope. People may be able to move towards pinker conversations with practice."

The Dartmouth study—which includes co-author Kiara Sanchez, a former assistant professor of psychological and brain sciences—is distinct from existing research on conversational dynamics because it suggests that divergence is an important part of getting the most of an exchange, O'Nell says. Most other studies focus on how speakers synchronize during conversation and become more similar to each other over time.

"By invoking this idea of pink noise, we're able to show how important it is for people to break away from each other as well," O'Nell says. "After all, speaking to a parrot would result in perfect alignment, but be a terrible conversation."

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Journal

Science Advances

DOI

10.1126/sciadv.aeb2684

Method of Research

Computational simulation/modeling

Subject of Research

People

Article Title

Pink noise in dyads’ semantic similarity trajectories predicts conversation enjoyment

Article Publication Date

6-Nov-2026

 

Extreme cold and drought events reveal thresholds in East Asian monsoon climate

Utrecht University

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“About one fifth of the world’s population depends on the East Asian monsoon for access to fresh water,” says Francien Peterse, Professor of Organic Geochemistry at Utrecht University’s Faculty of Geosciences (Dept. of Earth Sciences) and co-author of the study. “It is therefore crucial to understand how climate change affects this monsoon system, and especially the rainfall it brings.”

Separating temperature and precipitation

It is generally assumed that, over long timescales—tens to hundreds of thousands of years—the strength of the monsoon climate tracks changes in solar radiation: the more radiation, the more intense the summer monsoon, with warmer and wetter conditions, and vice versa. However, the methods most commonly used to study the past dynamics of this system often combine temperature and precipitation signals. This makes it difficult to distinguish temperature changes from changes in rainfall.

How is climate change affecting the monsoon system and the rainfall it brings? That’s what we aim to understand

Francien Peterse

 

In an earlier study, the researchers therefore developed a method to distinguish past changes in temperature from changes in precipitation. They based it on subtle variations in the molecular structure of the membranes of soil bacteria. “These bacteria adjust the structure of their membrane molecules when their environment changes. The adjustments caused by temperature differ from those caused by precipitation. This allows us to distinguish between temperature and precipitation—something that conventional methods are unable to do.”

Extreme cold and drought

In the current study, the researchers analysed fossil membrane molecules in a sediment sequence from the Chinese Loess Plateau. This allowed them to investigate how precipitation responded to temperature changes over the past 250,000 years. Hao Lu, lead author of the study, says: “We see that, over astronomical timescales, both temperature and precipitation track changes in incoming solar radiation, although precipitation sometimes responds only after a delay of a few thousand years. But we also found departures from this pattern: abrupt periods of extremely cold and dry conditions that can last for several thousand years.”

Abrupt climate change on land

The researchers compared their data with climate-model output. This showed that the extreme periods occur at predictable times: when incoming solar radiation falls below a certain level. “This threshold had already been identified in a study by one of our co-authors, but now, for the first time, we have evidence that crossing it actually triggered abrupt climate change on land. We also see that the climate only recovers once incoming radiation rises above the threshold again.”

“These abrupt changes in the monsoon climate occur mainly when CO₂ concentrations are low,” Peterse says. “This shows that the background climate state matters. These ancient events do not directly predict the extremes we face today, but they help us understand how solar radiation can produce abrupt climate responses."

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Journal

Communications Earth & Environment

DOI

10.1038/s43247-026-04060-3

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

Extreme cold–dry events in East Asia during glacials reflect insolation thresholds

Article Publication Date

10-Nov-2026