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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 Damodharan 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

Indian Scientists Find a New Way to Tune How Metals Interact with Light

Indian researchers have discovered a way to mechanically control how metals interact with light, opening new possibilities for programmable photonic chips and sensors.

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A scientist using a microscope and advanced laboratory equipment during nanophotonics research on the optical properties of metals.

For decades, scientists believed that a metal’s ability to interact with light was fixed once the material was made. Researchers in Bengaluru have now challenged that long-held belief by showing that simply stretching an ultrathin metal film can change its optical properties, a breakthrough that could help develop programmable optical chips and other advanced light-based technologies.

The study, led by researchers at the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), is the first to show that mechanical strain can directly change the way a metal responds to light. The findings could lead to reconfigurable photonic devices that work with today’s semiconductor manufacturing methods, making future optical technologies more flexible and energy efficient.

The discovery is based on a phenomenon called plasmon resonance, where free electrons on a metal’s surface move together when light falls on it. This allows light to be concentrated into extremely tiny spaces, making it useful for technologies such as highly sensitive biosensors, medical diagnostics, optical communication systems, imaging devices and photonic chips.

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 Schematic illustration of mechanical control of plasmon resonance in ultrathin films. Image credit: PIB

A key property behind this behavior is the plasma frequency, which determines how a metal responds to light. Scientists have long believed this property depends only on the metal’s composition and cannot be changed after the material is made. Although researchers have found ways to modify a metal’s optical behavior indirectly by changing its structure or surroundings, directly altering the plasma frequency had remained out of reach. The new study shows that mechanical strain can provide a simple new way to achieve this without changing the material itself.

Stretching Metal to Change Its Optical Response

To test their idea, the researchers used ultrathin films of titanium nitride (TiN), a material that is increasingly seen as an alternative to gold because it is more stable at high temperatures, resists chemical damage and is compatible with the manufacturing processes used to make computer chips.

The team produced two identical TiN films, each just 10 nanometres thick. One film was left unchanged, while the other was grown on a specially designed layer that gently stretched the material. This allowed the researchers to study the effect of mechanical strain without changing the metal’s composition.

Using high-resolution electron microscopy, they found that the stretched film responded differently to light than the unstretched one. Computer simulations explained why. Stretching the material made it easier for tiny defects, called nitrogen vacancies, to form inside the crystal. These defects released extra free electrons, increasing the number of electrons available to interact with light and changing the metal’s optical behaviour. Additional spectroscopy and X-ray diffraction experiments confirmed the results.

Why the Discovery Matters

The ability to change a metal’s optical properties using mechanical strain could open new possibilities for photonic technologies, which use light instead of electricity to process and transfer information. Compared with conventional electronics, photonic devices can operate at much higher speeds while using less energy and producing less heat.

Today, most plasmonic devices have fixed properties once they are manufactured. This limits how they can be used. The new approach suggests that future optical devices could be adjusted even after they are made, making them more versatile and easier to adapt for different applications. Such devices could improve optical sensors, imaging systems, communication technologies and next-generation computer chips.

“Our work shows that strain is a powerful and previously underexplored control knob for plasmonic properties in metals,” said Bivas Saha, Associate Professor at JNCASR and the study’s corresponding author. “The ability to mechanically reconfigure the optical response of a CMOS-compatible material like TiN transforms plasmonics from a static platform to an active and programmable one.”

The research also involved collaborators from the University of Sydney, Australia.

Although the study is still at the fundamental research stage, it challenges a long-held understanding of how metals behave and offers scientists a new way to design materials whose optical properties can be adjusted when needed. As demand grows for faster communication systems, artificial intelligence hardware and compact optical devices, the discovery could help lay the groundwork for a new generation of programmable photonic technologies.

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The Sciences

STEM Scholarships for First-Generation College Students: Breaking the Cycle of Poverty

STEM scholarships help first-generation college students access higher education, build careers and break cycles of generational poverty.

STEM scholarships can help first-generation college students overcome financial barriers and pursue careers in science, technology, engineering and mathematics.
Image credit: Stem.T4L/ Unsplash

STEM scholarships are helping first-generation college students overcome financial barriers, access technical education and build careers that can transform families and communities.

In many households across India, the dream of higher education is often overshadowed by the immediate need to make ends meet. For a first-generation college student, earning a university degree is more than a personal achievement; it is a responsibility carried on behalf of an entire family.

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While access to basic education has expanded significantly, entering specialised professional fields remains difficult for students from disadvantaged backgrounds. Science, technology, engineering and mathematics (STEM) disciplines offer one of the most effective pathways out of poverty, yet they are often the hardest to access. The challenge begins long before the first day of college. Talent alone cannot bridge the gap between a modest household and a modern laboratory. Beyond tuition fees, students face a range of hidden costs and barriers that make technical education difficult to pursue.

Without a financial safety net, many capable students are forced to abandon their studies or take up low-skilled jobs to support their families

The Financial Barrier to Technical Education

For a first-generation student, choosing to study engineering, medicine or other STEM disciplines can be a daunting financial decision. Unlike many other degree programmes, STEM courses often involve higher tuition fees, laboratory expenses and intensive academic schedules that leave little time for part-time work.

Without a financial safety net, many capable students are forced to abandon their studies or take up low-skilled jobs to support their families. This is where STEM-focused scholarships can make a meaningful difference.

The most effective scholarship programmes do far more than cover tuition. They often support living expenses, books, learning materials and travel costs. By reducing financial pressure, scholarships allow students to focus on their studies and complete their degrees successfully. Yet financial support alone is only one part of the solution.

Bridging the Skills Gap and Creating Livelihoods

The value of a STEM education extends well beyond individual success. In today’s technology-driven economy, technical skills have become increasingly valuable, opening doors to careers that can transform lives and communities.

First-generation graduates often find opportunities in fast-growing sectors such as healthcare, nursing, pharmacy, engineering and technology. Stable and well-paying jobs can help families move beyond cycles of poverty that may have persisted for generations.

For young women in particular, STEM scholarships can be transformative. Targeted support helps address barriers such as financial constraints, social expectations and unequal access to opportunities.

When a young woman from an underserved community becomes a healthcare professional, engineer or software developer, her success often inspires others around her. The impact extends beyond one individual, encouraging more students to pursue higher education and professional careers. In this way, scholarships help create a new generation of skilled professionals who better reflect the diversity of the society they serve.

Nurturing Growth Beyond the Classroom

There is growing recognition that scholarships should be viewed not simply as financial assistance but as an investment in human potential.

Many first-generation students face uncertainty when transitioning from education to employment. The strongest scholarship models therefore combine financial support with mentorship, career guidance and skills development.

Funding alone is not enough. Students also need exposure to professional environments and opportunities to develop workplace skills. Digital learning platforms, mentoring programmes, skill-building workshops and industry interactions can help bridge this gap.

When students are supported through a broader ecosystem, they are better prepared for life after graduation. They enter the workforce not merely as degree holders but as confident professionals equipped to compete in a rapidly changing economy.

Ultimately, targeted STEM scholarships can turn structural barriers into opportunities. By enabling talented students to access education, develop skills and secure meaningful careers, they help break cycles of generational poverty while contributing to a more equitable and prosperous society.

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Society

When Pollinators Vanish, Children Go Hungry—Here’s the Proof

A landmark study has, for the first time, traced a direct line from the collapse of wild insect pollinators to the malnutrition and poverty of farming families — reframing biodiversity loss as a global public health emergency.

Dipin Damodharan

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Pollinator Decline Threatens Nutrition, Farm Incomes: Study
Image credit: Tom Timberlake

Two billion. That is how many people on this planet eat what smallholder farmers grow. Not what agri-industrial combines harvest, not what commodity markets trade — what families with small plots of land pull from the soil, season after season, with the tools and seeds and knowledge they have. Two billion people. And a significant share of what keeps those harvests coming, what puts vitamins into the food and income into the household, has no name on any payroll, files no tax return, and has never once been thanked.

It is insects. Wild insects — bees, hoverflies, moths, beetles — moving flower to flower across millions of smallholder fields, doing work that no machine replicates and no subsidy replaces. Pollinator decline is dismantling that system quietly, field by field, season by season. A study published today in Nature, led by researchers at the University of Bristol, has for the first time traced exactly what that loss costs — not in abstracted ecosystem valuations, but in the vitamin A missing from a child’s diet, in the folate a pregnant woman never gets, in the farm income that does not arrive at the end of a harvest. The number at the end of that calculation is not a projection or a model. It is a measurement. And it is arresting.

Insect pollinators, the study found, are responsible for 44% of the farming income of the households tracked, and contribute more than 20% of dietary intake of vitamin A, folate and vitamin E — three nutrients whose deficiency is already linked to stunted child growth, weakened immunity and higher rates of disease. When pollinators vanish, the families don’t just grow less food. They grow less nutritious food, earn less money and become more vulnerable to illness. The cycle reinforces itself, downward.

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Ten Villages, One Year, and a Chain of Evidence

The study centred on ten smallholder farming villages and their surrounding landscapes in Nepal. Over the course of a year, the research team — drawn from universities and non-governmental organisations across Nepal, the United Kingdom, the United States and Finland — tracked three things simultaneously: which insects were visiting which crops, what those crops yielded and how nutritious they were, and what the farming families were actually eating and earning.

The impact of pollinator decline on food production and nutrition is high
Nepal’s smallholder farming communities are highly dependent on diverse range of pollinator-dependent crops. Image credit: Tom Timberlake

It is, in structural terms, the kind of study that is very hard to pull off. Most research on pollinators stops at the field boundary — counting bee visits, measuring fruit set, estimating yield differentials. This one kept going, all the way to the dinner table and the household ledger. That continuity of evidence is what makes it significant.

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The picture that emerged was not abstract or statistical. It was human. Over half the children in the study villages were too short for their age — a condition that goes by the clinical name of stunting and signals not just poor growth but compromised brain development, reduced immunity and diminished life prospects. The underlying cause, as the researchers documented it, was diet. And that diet depended, in ways the families could not easily see or control, on the insects working their fields.

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Pollinator Decline: The Hidden Hunger Nobody Is Counting

There is a term in public health circles for the condition that the Nepal families illustrate: hidden hunger. It describes not the obvious, acute starvation that makes headlines, but the chronic, silent insufficiency of vitamins and minerals that undermines health even when enough calories are being consumed. A quarter of the global population currently suffers from it. It is, by most measures, one of the largest sources of preventable illness on the planet, and it is almost entirely invisible in the way society keeps score of environmental damage.

When a species goes extinct, when a forest is cleared, when an insect population crashes — the accounting of loss is typically measured in biodiversity metrics, in ecosystem service valuations, or in the emotional register of what is no longer there to see. It is almost never measured in folate deficiency, in children’s height-for-age charts, in the likelihood of a farming family falling into debt after a bad harvest.

That is what this study changes. It is not the first to establish that pollinator decline matters for nutrition in the abstract. But it is the first to demonstrate, with tracked data from real communities over a real year, the size and mechanism of the effect — and to show that the effect flows not just through calories but through the specific micronutrients that are hardest to replace.

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Biodiversity as Medicine

Planetary Health — the field Dr Myers directs at Johns Hopkins — proceeds from a deceptively simple premise: human health and ecological health are not separate subjects. They are the same subject, studied from different ends. The degradation of natural systems is not a background condition to human development; it is one of the primary mechanisms by which human health is undermined.

That claim has long had intuitive force. What the Bristol study on pollinator decline provides is something more demanding: empirical evidence at the household level. It is one thing to argue that biodiversity loss will eventually compromise food security in a generalised way. It is another to show, village by village, season by season, that the decline in the bee community visiting a particular set of crops reduces particular vitamins in particular families’ diets by a measurable amount.

Bee on a flowering crop showing the impact of pollinator decline on food production and nutrition
Image credit: Tom Timberlake

The phrasing matters. Biodiversity is not a luxury. In policy conversations, the language of luxury — or alternatively, of long-term concern — has frequently served to push ecological questions down the agenda. If the relationship between pollinator health and child health is as direct as this study finds, that framing becomes harder to sustain.

What Goes When the Bees Go

It is worth being specific about the nutritional stakes. Vitamin A deficiency impairs vision, particularly in low light, and compromises the immune system’s ability to fight infections that would otherwise be routine. Folate deficiency during pregnancy causes neural tube defects in developing foetuses, among other effects. Vitamin E is a key antioxidant, and its deficiency is associated with neurological damage and weakened immune function. These are not marginal health concerns. They sit near the top of the global burden of preventable disease.

The crops most dependent on animal pollination — fruits, many vegetables, pulses — are also, not coincidentally, among the most concentrated sources of these particular nutrients. A diet from which pollinator-dependent produce has been reduced or removed can look adequate in calorie terms while being profoundly inadequate in micronutrient terms. The families studied in Nepal were, in effect, already living that deficit, in a context where pollinator diversity is declining.

Globally, insect populations have been under sustained pressure for decades. Pesticide use, habitat loss, monoculture farming, climate change and artificial light at night have all been implicated in declines that researchers have called, in some cases, ecological collapse. The mechanisms are various; the direction of travel is consistent.

The Good News: Reversible by Design

The research is, in its implications, genuinely alarming. But the researchers are also at pains to emphasise something that is easy to miss in the headline findings: the relationship between pollinators and nutrition runs in both directions. If pollinator decline causes nutritional harm, pollinator recovery can produce nutritional gains. And the actions required are not exotic.

Planting wildflowers at field margins. Reducing pesticide inputs. Keeping native bee colonies. These are the kinds of changes that do not require new technology or large capital investment. They require farmers to understand what is happening in their fields at a level of detail most have not previously been given reason to consider. The researchers are already working on that — translating their findings into practical guidance and working with local organisations, government partners and farmers in Nepal to implement changes on the ground.

The approach is now informing Nepal’s emerging National Pollinator Strategy, an effort to make pollinator-friendly practices a standard part of everyday agriculture rather than a specialist conservation concern. The researchers report that farmers who have adopted even modest changes are already seeing improvements in crop yields, income and nutrition — a feedback loop that runs in the direction of health rather than away from it.

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A Framework That Travels

Nepal is not an isolated case. Two billion people around the world depend on smallholder farming. Many of them face the same combination of circumstances: high dependence on pollinator-sensitive crops, limited dietary alternatives, micronutrient deficiencies that are already entrenched and ecosystems under stress. The findings from ten Nepali villages do not translate automatically to every agricultural context, but the framework — the method of tracing connections from insects to income to nutrition — does.

Diets even in industrialised countries still depend on pollinators and the ecosystems that sustain global agriculture. The buffer of wealth — the ability to import, substitute, supplement — is larger in wealthy countries, but it is not unlimited, and it does not protect the most economically vulnerable people even within those countries.

The lesson from this research on pollinator decline is less a specific warning about Nepal and more a methodological call to arms: to start measuring the connections that have, until now, been assumed or asserted but rarely demonstrated. When those connections are demonstrated, the case for protecting what remains of insect diversity becomes something different — not a moral preference or an aesthetic value, but a documented precondition for human health.

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The Stakes

A quarter of the world’s people are living with hidden hunger. Over half the children in ten Nepali villages are stunted. Forty-four percent of the farming income in those communities flows, invisibly, through the wings of insects that nobody counted or protected until researchers started looking. The insects are in decline.

The study’s authors are careful, as scientists should be, to describe what they found and what it implies rather than what must be done. But the shape of the implication is not obscure. The fabric of life — the phrase Dr Myers uses — is not an abstraction. It is the thing that puts vitamins in a child’s diet and money in a family’s pocket. Tear large enough holes in it, and the consequences are not primarily ecological. They are medical. They are economic. They are, in the most direct sense, human. That’s why the new findings on pollinator decline matter.

The bees were always doing the work. We just weren’t watching closely enough to see it — or to understand what we stood to lose.

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