18 February 2021
Researchers have discovered that the arrangement of existing memories in the brain is altered when we embed new memories. In fact, brain architecture is sophisticated enough to integrate new information while allowing new and old memories to interact, rather than having to forget old experiences to make room for new ones.
In a study published in Nature Neuroscience, a team from the University of Oxford and Imperial College London devised an experiment using graph theory to study this mechanism of memory integration in mice. They set up a task in which the animals learned that a particular compartment in a new environment contained sucrose. The mice also explored a familiar environment before and after forming this novel place-reward association.
This allowed the scientists to observe how the laying down of the new memory affected the network formed by patterns of co-activity among neurons in the hippocampus, a brain area that plays a major role in learning and memory. They found that the network topology in the hippocampus – the functional structure describing the patterns of coordinated neuron firing that occur when old memories are recalled – changed as the mice embedded new memories.
The team also found that during learning, the patterns of co-activity among neurons unfolded along particular directions in the ‘neuronal activity space’. This showed that novelty, spatial location, and reward experience were key factors involved in the process of integrating new memories. In addition, they discovered that high activity cells formed the core of each memory, while low activity cells contributed to the patterns of co-activity ‘on demand’, in order to segregate individual experiences. This finding highlights an important division of labour among hippocampal neurons.
Lead researcher Professor David Dupret at the Medical Research Council (MRC) Brain Network Dynamics Unit at the University of Oxford said: ‘This research sheds new light on the network mechanisms underlying the continual storage and recall of multiple memories in the hippocampus. Neuroscientists are now implementing new methods, such as in vivo imaging, to monitor large-scale neuronal populations over days and weeks of learning experience, to understand more about this process’.
Professor Simon Schultz from Imperial College London said: ‘This research highlights the value of an interdisciplinary approach to understanding the brain – by bringing a viewpoint from engineering and the mathematical sciences to bear upon the problem, we were able to tease out insights that would not have been possible based on a traditional approach to the study of memory.’
This research was funded by the Medical Research Council and the Engineering and Physical Sciences Research Council.
Notes to editors:
For further information and interview requests, contact: University of Oxford media team at firstname.lastname@example.org
Full paper citation: ‘Integrating new memories into the hippocampal network activity space’, Nature Neuroscience
Note that once the paper has been published online, it will be available at the following URL: https://www.nature.com/articles/s41593-021-00804-w
The University of Oxford
Oxford University has been placed number 1 in the Times Higher Education World University Rankings for the fifth year running, and at the heart of this success is our ground-breaking research and innovation. Oxford is world-famous for research excellence and home to some of the most talented people from across the globe. Our work helps the lives of millions, solving real-world problems through a huge network of partnerships and collaborations. The breadth and interdisciplinary nature of our research sparks imaginative and inventive insights and solutions.
The Nuffield Department of Clinical Neurosciences (NDCN)
NDCN has an established research and teaching portfolio with a national and international reputation for excellence. It comprises six sections: the Centre for the Prevention of Stroke & Dementia, the Division of Clinical Neurology, the Medical Research Council Brain Network Dynamics Unit, the Nuffield Division of Anaesthetics, the Nuffield Laboratory of Ophthalmology and the Wellcome Centre for Integrative Neuroimaging. The Department is based in the John Radcliffe Hospital and has developed a highly integrated and interdisciplinary environment in which research, teaching, clinical training and clinical care interact. This enables new approaches to the understanding, diagnosis and treatment of brain diseases.
Imperial College London
Imperial College London is one of the world's leading universities. The College's 20,000 students and 8,000 staff are working to solve the biggest challenges in science, medicine, engineering and business.
Imperial is the world’s fifth most international university, according to Times Higher Education, with academic ties to more than 150 countries. Reuters named the College as the UK's most innovative university because of its exceptional entrepreneurial culture and ties to industry.
Imperial staff, students and alumni are working round-the-clock to combat COVID-19. Imperial has nearly two thousand key workers, and is at the forefront of coronavirus epidemiology, virology, vaccine development and diagnostics. More than one thousand Imperial staff and students are volunteering to support the NHS.
Imperial College Centre for Neurotechnology
The Centre for Neurotechnology aims to foster collaborative research at the interface of neuroscience and engineering across the Faculties of Engineering, Medicine and Natural Sciences, as well as with satellites at Oxford and the Crick Institute. The Centre hosts the EPSRC Centre for Doctoral Training in Neurotechnology for Life and Health, which is training a new generation of researchers to develop and harness new technologies for understanding and treating brain disorders. In 2017 the Centre was formally recognised by Imperial College London as a Centre of Excellence in Neurotechnology.