Chairs
Professor Edwin M Robertson, Institute of Neuroscience and Psychology, University of Glasgow, Scotland
Professor Edwin M Robertson, Institute of Neuroscience and Psychology, University of Glasgow, Scotland
Edwin M Robertson holds the Chair in Brain & Cognitive Sciences at the Institute of Neuroscience & Psychology in Glasgow, UK. He uses a combination of behavioural analysis, brain imaging and brain stimulation to provide insight into the off-line processing of human memory. His work has revealed how the fate of a memory is controlled, the importance of brain state for this control, the degenerate organization of offline processing, and how the interactive organization of memories enables the creation of flexible and generalisable knowledge. Prior to his current position he held a number of faculty positions at Harvard Medical School, was a graduate and a medical student at the University of Oxford, and prior to that, was an undergraduate at the University of Cambridge.
09:00-09:05
Welcome by Royal Society
09:05-09:25
Same or seperate? Functions and mechanisms of memory replay during sleep and wake
Dr Susanne Diekelman, University of Tubingen, Germany
Abstract
Sleep strengthens and stabilizes newly acquired memories in an active process of system consolidation. This process is assumed to rely on covert reactivations of new memories that occur spontaneously after learning, mainly during slow-wave sleep (SWS), but can also be externally triggered by learning-associated memory cues. In a series of experiments, we show that the application of learning-associated odor cues during sleep resulted in an immediate stabilization of new memories, whereas similar odor reactivations in the wake state induced memory labilization. Functional magnetic resonance imaging revealed different activation patterns following reminder presentation during sleep and wakefulness. Moreover, different types of reminders (complete/incomplete) exerted different effects on memory during sleep and wakefulness. While in the wake state, only incomplete reminders but not complete reminders labilized the memory traces, both the incomplete reminder and the complete reminder stabilized memories during sleep. This evidence collectively suggests that reactivation has different effects on memory during wakefulness and sleep, presumably serving different functions for the dynamic long-term storage of memory.
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Dr Susanne Diekelman, University of Tubingen, Germany
Dr Susanne Diekelman, University of Tubingen, Germany
Dr Susanne Diekelmann is a Post-Doc and Research Associate at the Institute of Medical Psychology and Behavioural Neurobiology at the University of Tübingen. She studied Psychology and Philosophy at the Dresden University of Technology and at King’s College London. In 2011, she obtained her PhD at the University of Lübeck under the supervision of Jan Born. Her main research interest is on the functional role of sleep for processes of learning and memory formation, with a particular focus on memory reactivation during sleep. Her research has been published in a number of high-impact journals, including Nature Reviews Neuroscience, Nature Neuroscience, and Journal of Neuroscience. Beyond her research on sleep and memory, Susanne has a strong interest in philosophical and ethical questions arising from neuroscience research, particularly concerning cognitive enhancement.
09:25-09:45
Sleep structure and replay across species
Professor Daniel Margoliash, University of Chicago, USA
Abstract
The majority of sleep behavioural research is conducted in humans, results which are complemented by extensive animal experiments in rodents. Here we present neural and behavioural evidence for a role of sleep in sensorimotor vocal learning in juvenile and adult songbirds, and for perceptual learning in adult songbirds (the latter mostly behavioural work). We show deep similarities of the behavioural results in songbirds and humans, highlight similarities and differences between the songbird and rodent results, and discuss the implications of these similarities and differences. We show preliminary evidence that within Aves, the complex pattern of sleep observed in songbirds extends at least to parrots. Knowing the extent to which the behavioural and neurophysiological results apply broadly, beyond mammals and perhaps far across the animal kingdom, can open opportunities for developing new advantageous model systems to gain deeper insights into the neurobiology of sleep. Our results, in complement with recent data from reptiles and other poikilotherms and invertebrates, suggest the possibility of a broad diversity of species that exhibit sleep dependent processing. This places constraints on neuronal network models to explain these behaviours.
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Professor Daniel Margoliash, University of Chicago, USA
Professor Daniel Margoliash, University of Chicago, USA
Dr Margoliash is interested in brain mechanisms of behaviour, focusing on plasticity and vocal behaviour in songbirds, and more recently in humans. One set of studies has explored the role of sleep in developmental song learning and adult song maintenance. Single cell neuronal replay during sleep is a feature of certain song system forebrain neurons, providing a rare opportunity to examine the neurobiology of sleep dependent motor skill learning. Vocal production is efficiently described in a non-linear dynamical systems framework. Ongoing work examines neuronal representations and plasticity in this framework, for example the recently described novel form of information representation, such that a bird's song is mapped onto uniform intrinsic properties in a population of neurons, and feedback errors rapidly inducing inhomogeneity in that representation.
Dr Margoliash received his BSc, MSc and PhD from Caltech, completing his doctoral research on auditory responses of song system neurons in the laboratory of Masakazu (Mark) Konishi. He then conducted postdoctoral studies on echolocating bats with Nobuo Suga in Washington University (St. Louis) before joining the faculty at the University of Chicago. He is professor in the Department of Organismal Biology and Anatomy and the Department of Psychology.
09:45-10:05
Sleep replay and memory consolidation in the hippocampus and amygdala
Dr Gabrielle Girardeau, NYU Langone Medical Center, USA
Abstract
The hippocampus and the amygdala are two structures required for emotional memory. The hippocampus, through place cells, is believed to encode the spatial or contextual part of the memory. During slow-wave sleep, the activity of place cells is replayed in the same order as during the preceding learning epoch. These reactivations specifically occur during local field potential (LFP) short oscillatory events associated with highly synchronous neuronal activity called “ripples”. The group have shown previously that the specific suppression of ripples during sleep impairs performance on a spatial task, underlying their crucial role in memory consolidation. On the other hand, the amygdala processes the emotional valence of an event. Disrupting activity in the basolateral amygdala (BLA) immediately after training impairs performance on emotional tasks like contextual fear conditioning. However, how the amygdala and the hippocampus interact to consolidate an emotional event is yet unknown. To study that, the group designed a new task where the rats learn the location of an aversive stimulus. Using large scale simultaneous neuronal ensemble recordings in the hippocampus and BLA, we found coordinated reactivations between the two structures during sleep following training. Moreover, these reactivations specifically involve a small subset of BLA neurons that are modulated during hippocampal ripples and this modulation increases during sleep ripples following training. Hippocampal ripples during sleep thus emerge as a crucial time windows for intra-hippocampus and cross-structure reactivations sustaining the consolidation of spatial and emotional memories.
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Dr Gabrielle Girardeau, NYU Langone Medical Center, USA
Dr Gabrielle Girardeau, NYU Langone Medical Center, USA
Gabrielle Girardeau is a post-doctoral fellow in Dr Buzsaki's lab at the NYU Langone Medical Center in New York, USA. Her research focuses on the network mechanisms of memory consolidation, with a specific emphasis on sleep-dependent processes. In her current work, she is dissecting neuronal interactions between the amygdala and the hippocampus to better understand the emotional component of memory consolidation. She uses large-scale in-vivo recordings of neural ensembles in freely moving rodents to study how intra and cross-structural coordinated neural activity sustains the long-term stabilization of memories. Dr Girardeau is currently a Charles H. Revson Foundation Biomedical Fellow.
Dr Girardeau received her PhD from the College de France/University Pierre et Marie Curie, (Paris, France), where she contributed to unravel a key mechanism of hippocampus-dependent memory consolidation during slow-wave sleep. For this work, she was awarded the Best Thesis Award from the French Society for Neuroscience, The Major Advances in Biology Award from the French Academy of Science and a MaxPlanck/CNRS Neuroscience Award. Dr Girardeau is a member of the Society for Neuroscience (SfN) and the French Society for Neuroscience.
10:05-10:25
Mismatch, labilization and reinforcement during memory reactivation
Dr Olavo Amaral, Federal University of Rio de Janeiro, Brazil
Abstract
Due to their opposite behavioural outcomes, memory reconsolidation and extinction have usually been considered as separate entities, despite being induced by similar reactivation protocols. Based on modelling and pharmacological data, the group will argue that the two processes nevertheless seem to involve similar sets of plasticity mechanisms. One of these sets seems to be pharmacologically similar to the one involved in initial consolidation and Hebbian plasticity, while the second appears to be more involved with the labilization of existing memories and synaptic changes. Moreover, memory labilization mechanisms resemble those involved in forms of homeostatic plasticity, such as synaptic scaling. With this in mind, the group will discuss whether memory destabilization during reactivation might be a consequence of homeostatic-like plasticity induction, and why mismatch between learning and re-exposure could lead this to happen. On this basis, the group will argue that the field of memory updating might benefit from a paradigm shift in which reconsolidation and extinction, as well as online and offline reactivation, are viewed not as fully distinct processes but as different instantiations of common plasticity systems.
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Dr Olavo Amaral, Federal University of Rio de Janeiro, Brazil
Dr Olavo Amaral, Federal University of Rio de Janeiro, Brazil
Olavo Amaral is a professor at the Federal University of Rio de Janeiro, Brazil, holding a medical degree and a PhD in Biochemistry from the Federal University of Rio Grande do Sul. As a memory researcher, he is particularly interested in understanding memory labilization processes occurring in reconsolidation, extinction and forgetting. For this means, he works with behavioural studies in rodents and with simple computational models of neural networks, trying to put together findings at the molecular and circuit levels. He is also interested in initiatives to improve the reproducibility of behavioural neuroscience studies, particularly through the use of systematic reviews and meta-analysis. Finally, he is interested in the relationships between neuroscience and psychiatric nosology, and currently works on a non-fiction book dealing with the shifting frontiers between health and illness in contemporary society.
10:45-11:30
Discussion Session
Professor Loren Frank, HHMI and University of California, USA
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Professor Loren Frank, HHMI and University of California, USA
Professor Loren Frank, HHMI and University of California, USA
Loren Frank is Howard Hughes Medical Institute Investigator, Co-Director of the Kavli Institute for Fundamental Neuroscience and a Professor in the Department of Physiology at the University of California, San Francisco. He received his BA in Psychology and Cognitive studies from Carleton College, his PhD in Systems Neuroscience and Computation from M.I.T, and did post-doctoral research at Massachusetts General Hospital and Harvard University. His laboratory uses a combination of techniques to study the neural bases of learning, memory and decision-making. Dr Frank has received numerous awards for his scientific discoveries and his mentoring, including fellowships from the Sloan, McKnight and Merck Foundations as well as the Society for Neuroscience Young Investigator Award, the University of Indiana Gill Young Investigator Award, the UCSF Faculty Mentoring Award, and the College Mentors for Kids Inspire Award.
11:30-12:30
Hippocampal neurogenesis and forgetting
Professor Paul Frankland, Program in Neuroscience and Mental Health, Hospital for Sick children, Toronto, Canada
Abstract
Neurogenesis persists throughout life in the hippocampus, and there is a lot of interest in how the continuous addition of new neurons impacts hippocampal memory function. Behavioural studies have shown that artificially elevating hippocampal neurogenesis often facilitates new memory formation. However, since the integration of new neurons remodels existing hippocampal circuits, it has been hypothesized that hippocampal neurogenesis may also promote the degradation (or forgetting) of memories already stored in those circuits. Consistent with this idea, we have recently discovered that elevating rates of hippocampal neurogenesis after memory formation leads to forgetting. This finding changes the way we think about how hippocampal neurogenesis contributes to memory function, suggesting that it regulates a balance between encoding new memories and clearing out old memories.
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Professor Paul Frankland, Program in Neuroscience and Mental Health, Hospital for Sick children, Toronto, Canada
Professor Paul Frankland, Program in Neuroscience and Mental Health, Hospital for Sick children, Toronto, Canada
Paul Frankland is a Senior Scientist in the program in Neurosciences & Mental Health at the Hospital for Sick Children. He holds a Canada Research Chair in Cognitive Neurobiology, and is appointed as an Associate Professor in the Department of Psychology, Department of Physiology and Institute of Medical Science at the University of Toronto. His research focuses on modelling cognitive function and dysfunction in genetically-engineered mice. In these studies he hopes to characterize the roles of different proteins in neuronal plasticity, how different brain regions contribute to distinct cognitive processes, and how these are altered in disease states.