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The Sciences

Memory Formation Unveiled: An Interview with Sajikumar Sreedharan

“Our goal is to correct or rewire neural network activity so that memory can be preserved with minimal damage, especially during conditions such as aging, Alzheimer’s Disease, and mental health disorders.”

Dipin Damodharan

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Image credit: Sajikumar Sreedharan

In an enlightening conversation with EdPublica, Sajikumar Sreedharan, Associate Professor at the NUS Yong Loo Lin School of Medicine, Singapore, shares his research insights on memory formation and the transition from short-term to long-term memory. His areas of research include aging and neurodegeneration, the neural basis of long-term memory (LTM), and synaptic tagging and capture (STC) as an elementary mechanism for storing LTM in neural networks. He also explores metaplasticity as a compensatory mechanism for improving memory in neural networks. With a career spanning over two decades, Prof. Sreedharan discusses his key findings, innovative methodologies, and the significance of receiving the “Investigator” award from the International Association for the Study of Neurons and Brain Diseases. Join us as he reflects on his journey and the collaborative spirit that drives his research.


Edited Excerpts:

Your research has been recognized for significantly advancing our understanding of memory formation. Could you elaborate on your key findings related to the transition from short-term to long-term memory?

I have been working in the field of learning and memory since 2000. My first mentor in neuroscience was Prof. T. Ramakrishna, the founder and first head of the Life Sciences Department at the University of Calicut, Kerala, India. He was a great motivator, and we often had insightful discussions about learning and memory in the evenings. I had the chance to work with him for my master’s dissertation, which was my first real research experience. Prof. Ramakrishna encouraged me to expand my knowledge further, and he connected me with Dr. Shobi Valeri, a senior researcher in Delhi at the time.

Dr. Shobi soon left for Germany to pursue his Ph.D. and recommended me to DRDO (Defence Research and Development Organisation). Dr. Shobi is now a senior scientist at the National Institute of Nutrition in Hyderabad. I worked at DRDO for a year before moving to Magdeburg, Germany, where I began my Ph.D. under Prof. Juletta Frey. She is well-known in the field of learning and memory, particularly for her research on the cellular mechanisms involved in forming associative memory.

In Prof. Frey’s lab, I discovered how different pieces of information can link together to form long-term memories. This work later inspired the development of many computational models of memory. After completing my Ph.D., I did my postdoctoral studies with Prof. Martin Korte in Braunschweig. There, I discovered how activating neurons before learning could enhance memory formation in the future, a process known as metaplasticity—an exciting and emerging area of neuroscience.

“Using animal models, we have uncovered the role of specific brain regions, like CA2 and CA1, in forming social and spatial memories—both of which are significantly affected by aging, neurodegenerative diseases, and mental health conditions


Since 2012, I have been working at the National University of Singapore, where I have focused more on aging, neurodegeneration, and mental health. Using animal models, we have uncovered the role of specific brain regions, like CA2 and CA1, in forming social and spatial memories—both of which are significantly affected by aging, neurodegenerative diseases, and mental health conditions.

How do you approach the study of molecular mechanisms in memory, and what methodologies do you find most effective?

In my lab, we approach research questions by examining them from different angles—molecular, cellular, behavioural, and system-level. We choose the most appropriate method depending on the specific question we’re investigating. I can’t say that one method is better than the others because each plays an important role in confirming our findings.

Recently, we’ve been using optogenetic and chemogenetic tools, which allow us to target and stimulate specific neurons. These methods are particularly helpful because they ensure precision in how we activate or deactivate brain cells.

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Congrats on receiving the “Investigator” award from the International Association for the Study of Neurons and Brain Diseases. What does this recognition mean to you personally and professionally?

Thank you for your kind words. As a researcher, I feel proud and happy that my work is being recognized internationally. Professionally, this recognition is a significant motivation to continue pursuing my research.

This achievement is not just mine alone—I owe it to all my Ph.D. students, postdocs, and research technicians who have worked with me over the past 20 years. This award is for them as well.

How do you feel your work contributes to the broader scientific community, especially concerning memory impairments related to aging and mental health?

I am the Research Director of the Healthy Longevity Translational Research Programme at the School of Medicine, National University of Singapore, where we have more than 36 scientists working on various aspects of healthy aging. One of our key areas is brain health. Living a long life is not meaningful without a healthy brain.

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Image by Moondance from Pixabay

I am one of the principal investigators studying how neural networks are impaired during aging and neurodegeneration. My wife, Dr. Sheeja Navakkode, is also a neuroscientist, focusing on Alzheimer’s disease using animal models. Neural networks undergo tremendous changes during aging and in various mental health conditions. Our goal is to correct or rewire neural network activity so that memory can be preserved with minimal damage, especially during conditions such as aging, Alzheimer’s Disease, and mental health disorders.

(Read the full interview in the upcoming December 2024 issue of EdPublica magazine.)

Dipin is the Co-founder and Editor-in-Chief of EdPublica. A journalist and editor with over 15 years of experience leading and co-founding both print and digital media outlets, he has written extensively on education, politics, and culture. His work has appeared in global publications such as The Huffington Post, The Himalayan Times, DailyO, Education Insider, and others.

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The Sciences

Scientists Crack the Genetic Code Behind Seedless Grapes

Indian researchers reveal how genetic mutations create the popular seedless varieties consumers love, opening doors to better grape breeding

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Scientists have finally unlocked the mystery behind one of our favourite fruit features – seedless grapes. A study by Indian researchers has decoded the genetic mechanisms that create seedless grapes, potentially revolutionizing how we breed these popular fruits.

The Science Behind Seedless Success

The research, led by Dr. Ravindra Patil at the Agharkar Research Institute (ARI) in Pune, India, examined why some grapes develop without seeds while others don’t. Published in BMC Plant Biology, the study focused on a seedless mutant derived from the high-yielding grape variety ARI-516.

Using advanced genomic tools, the team discovered that pollen sterility is the key culprit behind seedlessness. The seedless grapes showed:

  • Abnormal pollen structure with very low viability
  • Complete inability of pollen grains to germinate
  • Smaller female reproductive structures compared to seeded varieties
  • Disrupted fertilization processes leading to seedless berry formation

Genetic Detective Work

The researchers employed cutting-edge techniques to crack the code:

Transcriptomic Analysis: RNA sequencing revealed that genes crucial for pollen development, cell division, and hormone signaling were significantly “switched off” in seedless varieties.

Whole-Genome Sequencing: This identified multiple insertion-deletion mutations (InDels) in genes responsible for pollen development, essentially breaking the normal seed formation process.

The evidence points to parthenocarpy – a natural process where fruits develop without fertilization due to reproductive defects.

Why This Matters

This discovery isn’t just academic curiosity. Seedless grapes represent a massive global market, with consumers strongly preferring them for:

  • Fresh consumption
  • Raisins and dried products
  • Juices and processed foods

The research provides molecular markers that grape breeders can use to:

  • Develop new seedless varieties faster
  • Improve fruit quality and yield
  • Create grapes better adapted to different climates

Impact on Agriculture

Dr. Patil’s team has conducted one of the most comprehensive studies on grape seedlessness using modern genomic tools. This breakthrough could significantly accelerate breeding programs worldwide, benefiting both grape growers and consumers who enjoy these convenient, seed-free fruits.

The study represents a perfect example of how understanding nature’s genetic mechanisms can lead to practical agricultural improvements, potentially transforming grape cultivation and meeting growing global demand for high-quality seedless varieties.

The research was conducted in collaboration with Savitribai Phule Pune University and represents a significant advancement in horticultural genomics.

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Climate

Study Finds Warming Could Slightly Boost Atmosphere’s Methane-Cleaning Capacity

New research suggests climate warming may modestly enhance the atmosphere’s ability to break down methane, though competing chemical processes add uncertainty.

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New research suggests climate warming may modestly enhance the atmosphere’s ability to break down methane, though competing chemical processes add uncertainty.
Image credit: MIT News; iStock

New research suggests climate warming may modestly enhance the atmosphere’s ability to break down methane, though competing chemical processes add uncertainty.

A new study by researchers at the Massachusetts Institute of Technology (MIT) finds that rising global temperatures could slightly increase the atmosphere’s ability to break down methane, one of the most potent greenhouse gases.

Methane is a major driver of global warming, second only to carbon dioxide. However, it does not persist as long in the atmosphere due to the presence of hydroxyl radicals—highly reactive molecules often described as the “atmosphere’s detergent” for their role in breaking down pollutants.

Balancing Effects of Water Vapour and Natural Emissions

The MIT team developed a new atmospheric model to understand how hydroxyl radical (OH) levels may respond to warming temperatures. Their findings reveal a complex balance of competing effects.

As global temperatures rise, atmospheric water vapour is expected to increase, boosting OH levels by about 9%. However, higher temperatures will also lead to increased emissions of natural gases from plants—known as biogenic volatile organic compounds—which can reduce OH levels by approximately 6%.

The net effect, according to the study, is a modest increase of around 3% in the atmosphere’s capacity to break down methane under a 2°C warming scenario.

Why Hydroxyl Radicals Matter

Hydroxyl radicals play a critical role in regulating atmospheric chemistry. They react with methane and other gases, breaking them down into less harmful compounds.

“About 90 percent of the methane that’s removed from the atmosphere is due to the reaction with OH,” said study author Qindan Zhu in a statement.

Beyond methane, OH also helps remove air pollutants and gases that affect public health, including ozone.

“There’s a whole range of environmental reasons why we want to understand what’s going on with this molecule,” said Arlene Fiore, a professor at MIT.

New Model Offers Deeper Insights

To conduct the study, researchers developed a model called “AquaChem,” which simulates atmospheric chemistry under different climate scenarios. The model builds on simplified “aquaplanet” systems, allowing scientists to isolate atmospheric processes without the complexity of land and ice interactions.

Using this model, the team compared current climate conditions with a scenario in which global temperatures rise by 2°C—widely considered a likely outcome without significant emissions reductions.

Uncertainty Around Natural Emissions

Despite the findings, researchers caution that there is still significant uncertainty—particularly regarding how plant emissions will respond to climate change.

Biogenic emissions, such as isoprene released by trees, appear to play a major role in influencing OH levels but remain difficult to predict accurately.

Future research will aim to refine these estimates and better understand how different climate scenarios could affect atmospheric chemistry.

Implications for Climate Projections

Even small changes in hydroxyl radical levels can have significant implications for how methane accumulates in the atmosphere.

“Understanding future trends of OH will allow us to determine future trends of methane,” Zhu said.

As methane continues to rise alongside carbon dioxide, insights into these chemical processes will be critical for improving climate models and informing mitigation strategies.

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Earth

Study Reveals How Ocean Bacteria Drive Plastic Biodegradation

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MIT researchers uncover how ocean bacteria collaborate to degrade biodegradable plastics, offering new hope for tackling plastic waste.
Image credit: Mali Maeder/Pexels

Plastic biodegradation is emerging as a critical solution to the global waste crisis, and new research from Massachusetts Institute of Technology offers important insights into how this process actually works in nature.

A new study by researchers at Massachusetts Institute of Technology has shed fresh light on how bacteria in marine environments collaborate to break down biodegradable plastics—offering critical insights into tackling the global plastic waste crisis.

Biodegradable plastics have long been seen as a potential solution to mounting environmental pollution. However, scientists have struggled to determine how long these materials persist in real-world conditions and how microbial communities contribute to their breakdown.

The study, published in Environmental Science and Technology, marks one of the first efforts to identify the specific roles individual bacterial species play in plastic biodegradation.

“Plastic biodegradation is highly dependent on the microbial community where the plastic ends up,” says lead author Marc Foster, a PhD researcher in the MIT-WHOI Joint Program. “It’s also dependent on the chemistry of the plastic itself.”

Unlike earlier studies that focused on single microbes, the MIT team examined how multiple bacterial species work together—a more realistic representation of how plastics degrade in nature.

The researchers studied a widely used biodegradable plastic known as an aromatic aliphatic co-polyester, commonly found in shopping bags, food packaging, and agricultural films.

Samples of this plastic were first exposed to seawater in the Mediterranean, allowing natural bacterial communities to form biofilms on their surface. Scientists then isolated and analysed these microbes in the lab.

Key findings include:

  • One bacterium, Pseudomonas pachastrellae, was able to break down the plastic polymer into smaller chemical components.
  • Other bacterial species were needed to consume those individual chemicals, including terephthalic acid, sebacic acid, and butanediol.
  • No single bacterium could complete the entire degradation process alone.

When researchers combined five complementary bacterial species, they were able to replicate the full degradation process observed in a larger microbial community.

“This complementary function was essential,” Foster explains. “None of the bacteria alone could achieve the same level of degradation as when they worked together.”

Why Plastic Biodegradation Rates Vary

The findings suggest that the speed and efficiency of plastic biodegradation depend on several key factors:

  • Microbial diversity in the environment
  • Chemical composition of the plastic
  • Environmental conditions such as temperature and depth

Notably, the study also found that the same bacterial community could not degrade a different type of plastic, indicating that microbial systems may be highly material-specific.

Implications for Future Plastic Recycling Solutions

The research represents an important step toward developing microbial recycling systems that could convert plastic waste into useful materials.

Plastic biodegradation challenge with discarded plastic materials
Image credit: Lars H Knudsen/Pexels

By understanding how bacteria interact with plastics at a molecular level, scientists could:

  • Design plastics that degrade more predictably
  • Engineer microbial communities for faster plastic breakdown
  • Develop biological recycling technologies

Foster notes that future work will explore how to optimise bacterial combinations and improve enzyme interactions with plastic surfaces.

A Step Forward in Tackling the Plastic Waste Crisis

With more than half of global plastic waste ending up in landfills or the environment, understanding plastic biodegradation is crucial for sustainable material design.

This study highlights a fundamental shift in perspective: plastic degradation is not driven by a single organism, but by complex microbial collaboration.

As research advances, such insights could help bridge the gap between biodegradable materials and real-world environmental outcomes—bringing science closer to solving one of the planet’s most pressing pollution challenges.The study, published in Environmental Science and Technology, marks one of the first efforts to identify the specific roles individual bacterial species play in plastic biodegradation.

“Plastic biodegradation is highly dependent on the microbial community where the plastic ends up,” says lead author Marc Foster, a PhD researcher in the MIT-WHOI Joint Program. “It’s also dependent on the chemistry of the plastic itself.”

Unlike earlier studies that focused on single microbes, the MIT team examined how multiple bacterial species work together—a more realistic representation of how plastics degrade in nature.

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