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What is a memory?

Is it a distinct pattern of brain activity, a blueprint for future behaviour, or a skill that we can improve with a little training? Probably all these things and more, argues Jon Simons, Professor of Cognitive Neuroscience in the Department of Psychology and Head of the School of the Biological Sciences.

Jon’s Memory Lab studies all aspects of memory. They invite volunteers to complete memory tasks online, in the laboratory, or sometimes while lying in an MRI machine while the team scans their brains. 

If memory serves

The biochemical changes that represent memories range across the brain’s real estate. A long list of factors determine which brain areas light up during the experience: whether a memory is being encoded or reconstructed, whether it's an old or a new pattern, and what kind of information it deals with.

“We know that the hippocampus is crucial for forming new memories, but it’s not necessarily the permanent storage site," Jon says. "For long-term storage, we also recruit cortical areas – the frontal lobes, temporal lobes, parietal lobes and more.”

To plot a route through tangled terrain, researchers divide memory into different types. Short-term memory lasts a minute at most and has a limited capacity – around 7 items give-or-take, according to Harvard’s George Miller in the 1950s. Think of repeating numbers to yourself while jotting down someone’s phone number. If we don’t record those numbers fast enough, they’ll fade quickly. 

But even short-term memory isn’t unitary. Alan Baddeley (Churchill 1959), former director of Cambridge’s Medical Research Council (MRC) Applied Psychology Unit (now called the MRC Cognition and Brain Sciences Unit), coined a new way of understanding how short-term memories are stored and manipulated. His 'working memory' model proposes that separate brain systems deal with different kinds of inputs. One part rehearses and replays sounds, for instance, while another holds visual information like a ‘mental canvas’. 

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This is different yet again from our long-term memories. These deeper experiences can stay with us for a lifetime. Recalling them can be thought of as a kind of ‘mental time-travel’, allowing us to subjectively relive past events complete with the sights, smells and sounds of cherished scenes.

Researchers now believe that we reconstruct our memories each time we experience them. From scant traces, we extrapolate the narrative of what happened. In this way, memory is a creative act, not a simple recap. One classic Cambridge study revealed how our memories are morphed by bias, beliefs, feelings and expectations.
 

Cambridge’s long memory

Enter the elegant study of Sir Frederic Bartlett, Cambridge’s first Psychology professor. 

Bartlett’s book ‘Remembering’ (1932) made use of a now famous story: the war of the ghosts. 

In this Native American folk tale, a man meets warriors paddling their canoes downriver, who invite him to join a war party. He later realises the men are ghosts, waging war on the living. 

Bartlett taught his Edwardian undergraduates this tale, then asked them to retell it in their own words. Over several retellings, his students altered key elements of the story so that it sounded more like the world they knew. ‘Canoes’ became ‘boats’, while mentions of ‘spirits’ were dropped altogether.

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Bartlett's study showed the effects of culture on recall, and how the changes we make to our memories aren’t random. Even if we’re not conscious of doing so, we prefer to change story elements so that they align with our expectations, biases and cultural norms.

This feature of memory has massive implications for how we remember the past. Eye-witness testimony will be prey to the same biases. Unintentional errors, made in favour of what is familiar to us, are very difficult to avoid.

Another titan of memory research was an undergraduate while Bartlett was teaching. During World War II, Brenda Milner (Newnham 1936) helped the Psychology department repurpose itself for the war effort. After this, Milner moved to Canada to analyse patient Henry Molaison (formerly known as H M). Molaison would become one of the most famous patients in all of psychology. 

Molaison had profound amnesia. This was due to experimental surgery, where doctors removed his hippocampus to try and improve his epilepsy. Milner meticulously documented how Molaison’s memory functioned after surgery. She showed how he was unable to form new memories or remember events from the years leading up to his surgery, but that his memories from earlier in life remained intact. This work transformed our understanding of the hippocampus’ role in memory.

Psychologists like Milner and Bartlett showed us the primacy of the hippocampus and highlighted the creative nature of memory. Modern Cambridge researchers can take our investigations even further.
 

Peak performance

With all we now know about memory, can we understand what makes for better performance?

Together with Professor Simon Baron-Cohen and his team at the Autism Research Centre, Jon is currently studying thousands of the UK’s best memorisers to find the keys to their prowess. Volunteers completed a battery of memory tests online – the best performers then came for brain scans and further testing in the lab.

Their early results suggest some interesting traits, as well as the strategies people use to enhance their abilities. 

“There's a psychological trait called ‘systemising’,” says Jon. “It's found in people who have a drive to analyse and construct rule-based ways of thinking. Those kinds of people seem to be more likely to have exceptional memories.”

Simon Baron-Cohen was the first to define this trait. He did so in relation to people on the autism spectrum, for whom ‘systemising’ is set very high. 

So if you happen to think like a ‘systemiser’, you may have a better memory. If you don’t, there are also concrete strategies to boost your memory capacities.

“Mnemonics are an evidence-based technique that can improve our memories,” Jon explains. “They often involve thinking spatially. Start by visualising somewhere you know well, then mentally ‘place’ important information in that map. You can then 'travel through' that map when recalling.”

Think Sherlock’s ‘mind palace’ from the BBC adaptation of Arthur Conan Doyle’s books. Jon points out that pre-BBC, this strategy was familiar to ancient Greek and Roman orators. They called it the method of loci, using it as a way to remember extremely long speeches. It can also be helpful for everyday tasks, like remembering a shopping list.

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Jon’s tip for this method is to make the memory triggers striking. Associate the eggs on your shopping list with a fire-breathing dragon guarding its young, for example, and the sensory impression might be distinct enough to stand out from the background noise. 

“The more bizarre the better! Our memories have a big job in trying to differentiate one memory from another. We can help it out by making key information more distinctive. This helps our brains to distinguish memories from one another, and stop irrelevant ones from overlapping or interfering.”

Indeed, one of the functions of the hippocampus is to perform pattern separation – trying to make our memories distinct. If memories are too similar, we find it harder to recall specific experiences. 

This might go some way to explaining the ‘brain fog’ many experienced during COVID-19 lockdowns. With days inside tending to repeat familiar routines, we had less distinct and varied experiences. Our brains were less able to create rich, meaningful memories. Looking back on 2020 and 2021, people find it hard to separate what happened when.

There’s a lesson for non-lockdown living here too. If we want a rich life that feels like it lasts longer and is full of accessible, interesting memories, we should prioritise variety in our experience.

To further improve memory function, we should strive to decrease stress, fear and anxiety (where possible). These emotional states increase our cognitive load and reduce our memory abilities.

“When anxious thoughts flood our minds, they compete for space in our working memory and impair our ability to recall long-term memories. They pull attention and resources away from the things we’d like to focus on. If we can find ways to reduce stress and anxiety, our memory can often bounce back.”

While this might be easier said than done, science has concrete recommendations for reducing stress and anxiety. Done consistently, a healthy diet, regular exercise and a good sleep schedule, as well as techniques like mindfulness practice, can have transformative effects. 

Researchers like Jon are deepening our understanding of what memories are. The Memory Lab follows an illustrious line of Cambridge psychologists who identified key pieces of memory’s endless puzzle. Wherever the next steps lead, they will affirm a wonder of nature: the intricate patterns our mind weaves to make sense of the world outside.

For a handy guide to building mental resilience, check out Brain Boost by Dr Barbara Sahakian and Dr Christelle Langley. To focus on fighting anxiety with scientific techniques, try Dr Olivia Remes.

To find out how you can participate in Memory Lab studies, get in touch.

By tying together more than a century of memory research at Cambridge, the Memory Lab gives us tangible ways to improve, preserve and understand our memory.

When anxious thoughts flood our minds, they compete for space in our working memory and impair our ability to recall long-term memories. If we can find ways to reduce stress and anxiety, our memory can often bounce back.Jon SimonsSusana CamachoJon Simons, by Susana Camacho

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Findings from a major Cambridge-led study inspired psychologists to co-produce a picture book that helps parents develop a deeper understanding of how their child is coping with the first year of school.

The metals have previously been shown to damage the health of pollinators, which ingest them in nectar as they feed, leading to reduced population sizes and death. Even low nectar metal levels can have long-term effects, by affecting bees’ learning and memory - which impacts their foraging ability.

Researchers have found that common plants including white clover and bindweed, which are vital forage for pollinators in cities, can accumulate arsenic, cadmium, chromium and lead from contaminated soils.

Metal contamination is an issue in the soils of cities worldwide, with the level of contamination usually increasing with the age of a city. The metals come from a huge range of sources including cement dust and mining.

The researchers say soils in cities should be tested for metals before sowing wildflowers and if necessary, polluted areas should be cleaned up before new wildflower habitats are established.

The study highlights the importance of growing the right species of wildflowers to suit the soil conditions. 

Reducing the risk of metal exposure is critical for the success of urban pollinator conservation schemes. The researchers say it is important to manage wildflower species that self-seed on contaminated urban land, for example by frequent mowing to limit flowering - which reduces the transfer of metals from the soil to the bees.

The results are published today in the journal Ecology and Evolution. 

Dr Sarah Scott in the University of Cambridge’s Department of Zoology and first author of the report, said: “It’s really important to have wildflowers as a food source for the bees, and our results should not discourage people from planting wildflowers in towns and cities.

“We hope this study will raise awareness that soil health is also important for bee health. Before planting wildflowers in urban areas to attract bees and other pollinators, it’s important to consider the history of the land and what might be in the soil – and if necessary find out whether there’s a local soil testing and cleanup service available first.”

The study was carried out in the post-industrial US city of Cleveland, Ohio, which has over 33,700 vacant lots left as people have moved away from the area. In the past, iron and steel production, oil refining and car manufacturing went on there. But any land that was previously the site of human activity may be contaminated with traces of metals.

To get their results, the researchers extracted nectar from a range of self-seeded flowering plants that commonly attract pollinating insects, found growing on disused land across the city. They tested this for the presence of arsenic, cadmium, chromium and lead. Lead was consistently found at the highest concentrations, reflecting the state of the soils in the city.

The researchers found that different species of plant accumulate different amounts, and types, of the metals. Overall, the bright blue-flowered chicory plant (Cichorium intybus) accumulated the largest total metal concentration, followed by white clover (Trifolium repens), wild carrot (Daucus carota) and bindweed (Convolvulus arvensis). These plants are all vital forage for pollinators in cities - including cities in the UK - providing a consistent supply of nectar across locations and seasons.

There is growing evidence that wild pollinator populations have dropped by over 50% in the last 50 years, caused primarily by changes in land use and management across the globe. Climate change and pesticide use also play a role; overall the primary cause of decline is the loss of flower-rich habitat.

Pollinators play a vital role in food production: many plants, including apple and tomato, require pollination in order to develop fruit. Natural ‘pollination services’ are estimated to add billions of dollars to global crop productivity. 

Scott said: “Climate change feels so overwhelming, but simply planting flowers in certain areas can help towards conserving pollinators, which is a realistic way for people to make a positive impact on the environment.”

The research was funded primarily by the USDA National Institute of Food and Agriculture.

Reference 
Scott, S.B.& Gardiner, M.M.: ‘Trace metals in nectar of important urban pollinator forage plants: A direct exposure risk to pollinators and nectar-feeding animals in cities.’ Ecology and Evolution, April 2025.  DOI: 10.1002/ece3.71238
 

Wildflowers growing on land previously used for buildings and factories can accumulate lead, arsenic and other metal contaminants from the soil, which are consumed by pollinators as they feed, a new study has found.

Our results should not discourage people from planting wildflowers in towns and cities. But.. it’s important to consider the history of the land and what might be in the soil."Sarah ScottSarah ScottChicory growing in a vacant lot

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Now in its eighth year, the Fellowship provides financial support for a postdoctoral placement of one to two years at a world-class research institution.

The funding equips scientists to apply their knowledge to a new field of study with the goal of accelerating discoveries, and to develop their leadership potential.

Dr Poppy Oldroyd, a 2025 Schmidt Science Fellow from the Department of Engineering, plans to pioneer a new frontier in understanding brain communication through optical measurements, ultimately advancing treatments for memory-related diseases.

The human brain communicates through intricate networks of neurons, crucial for learning and memory. However, how these neural conversations translate into memory formation remains a mystery in neuroscience. Oldroyd’s research aims to use light-based tools, like advanced optogenetics, to explore these pathways in detail. By uncovering how specific brain circuits contribute to learning and memory, this research could revolutionise our understanding of these essential brain functions. 

Ultimately, this knowledge may enhance our comprehension of memory-related disorders like Alzheimer’s disease and epilepsy.

Dr Matthew McLouglin, a 2025 Schmidt Science Fellow from the Cambridge Stem Cell Institute, plans to develop tools to study how our cells age in real time. This will help us understand why we age and how we might promote healthy aging to improve quality of life in the elderly.

Our DNA is organised into structures called chromosomes. Each chromosome has a protective cap, the ‘telomere’, which is partially lost with each cell division. In old age, cells cannot function properly due to the loss of telomeres, increasing the risk of age-related diseases such as cancer and dementia. McLoughlin will use cutting-edge imaging technology to track the loss of telomeres over time, understanding how telomeres are lost and why this stops cells from functioning.

Oldroyd and McLoughlin join a community of 209 Schmidt Science Fellows from nearly 40 countries who are leaders in interdisciplinary science.

“Philanthropic funding of scientific research, and especially support of early-career researchers, has never been more important,” said Wendy Schmidt, who co-founded Schmidt Science Fellows with her husband, Eric.

“By providing Schmidt Science Fellows with support, community, and freedom to work across disciplines and gain new insights, we hope they’ll tackle some of the world’s most vexing challenges, achieve breakthroughs and help create a healthier, more resilient world for all.”

Established in 2017, Schmidt Science Fellows is a programme of Schmidt Sciences delivered in partnership with the Rhodes Trust.

The 2025 Fellows represent 15 nationalities, including researchers from Jordan and the United Arab Emirates for the first time in the programme’s history.

This year’s cohort will work on a range of problems from cancer treatment to quantum technologies to sustainability.

Alongside their research Placement, Fellows participate in a 12-month interdisciplinary Science Leadership Programme.

Each year, Schmidt Science Fellows works in partnership with more than 100 universities to identify candidates for the Fellowship.

Nominees are selected via an application process that includes an academic review with panels of experts in their original disciplines and final interviews with a multidisciplinary panel of scientists and private sector leaders.

“The Schmidt Science Fellows Program is cultivating a dynamic global community of remarkable scientists and champions of interdisciplinary research,” said Stu Feldman, Chief Scientist at Schmidt Sciences.

“Their work exemplifies Schmidt Sciences’ commitment to support pioneering approaches that will drive the next era of discovery and innovation.”

The 2025 Schmidt Science Fellows represent 27 nominating universities, including, for the first time, McGill University in Canada, RWTH Aachen University in Germany, Tecnológico de Monterrey in Mexico, University of California, Los Angeles in the US, and University of Groningen in the Netherlands.

Two University of Cambridge researchers are among the thirty-two early career researchers, tackling issues from improving food security to developing better medical implants, who have been announced as the 2025 Schmidt Science Fellows.

Schmidt Science FellowsPoppy Oldroyd (left) and Matthew McLoughlin (right)

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