Declarative memory encompasses representations of specific events as well as knowledge extracted by accumulation over multiple episodes. To investigate how these different sorts of memories are created, we developed a new behavioral task in rodents. The task consists of 3 distinct conditions (stable, overlapping, and random). Rodents are exposed to multiple sample trials, in which they explore objects in specific spatial arrangements, with object identity changing from trial to trial. In the stable condition, the locations are constant during all sample trials even though the objects themselves change; in the test trial, 1 object’s location is changed. In the random condition, object locations are presented in the sample phase without a specific spatial pattern. In the overlapping condition, 1 location is shared (overlapping) between all trials, while the other location changes during sample trials. We show that in the overlapping condition, instead of only remembering the last sample trial, rodents form a cumulative memory of the sample trials. Here, we could show that both mice and rats can accumulate information across multiple trials and express a long-term abstracted memory. [More information in the Publications section]
The brain is constantly active in sleep and wakefulness. Most of its activity is spontaneous, that is, it is not provoked by any external stimulus. This activity is key to our cognitive processes, and is highly structured.
There is a network in the brain, the so-called default mode network (DMN), that is actually more active when we are not doing anything than when we are engaged in cognitive activities.
Our key hypothesis is that the default mode network is also crucial for memory, because of its tight link to the hippocampus, the ‘hub’ of the memory network in the brain.
Thanks to an ERC Advanced Grant (approx. 2.5 million€) will use advanced optical imaging to observe memory replay globally in the brain, testing the hypothesis that the DMN is the glue that keeps the whole memory together.
If you are a specialist of imaging (VS/Ca2+/2P) or a computational person interested in a project with resting state networks, memory and computation, please contact Francesco Battaglia at email@example.com
Three positions are available (preferred start: first half 2019, contract duration, 2-4 years) for PhD students and postdocs, funded by a Dutch NWO Exact sciences TOP grant. The researchers will develop methods for the unsupervised pattern detection in neural data based on Optimal Transport theory, developing on the idea described in the paper by Grossberger et al. PLoS Comp. Biol. 2018
We look for a combination of expertise, ideally one mathematician, one computer scientist/machine learning specialist, and one computational neuroscientists. The researchers will be embedded in the Memory Dynamics Lab (co-leaders, FP Battaglia and L Genzel), a rapidly growing group active in the exploration of mechanisms of memory, and will have access to large datasets from behavioral neurophysiology experiments from the group, as well as data obtained via external collaborations. Dr. Martin Vinck (ESI Frankfurt) and Dr. Paul Tiesinga (Donders Institute) will be key collaborators on this project
For information, please contact Francesco Battaglia at firstname.lastname@example.org
See also https://www.fens.org/News-Activities/Jobs/job-21183/
Starting with Donald Hebb in the 1940s, neuroscientists have speculated that memories are encoded in the activity of groups of cells, or cell assemblies, that fire in precise sequences of activation. Thus, the memory representation of the title of the book you just read may correspond in the brain to the activation of neuron 7, then neuron 15, then neuron 3, and so on. Instead, the memory of a scene when your aunt greeted you with a hug may be encoded as a neural sequence starting with 15-43-5-7. This encoding scheme has big theoretical advantages as it would enable the storage of a combinatorially huge number of patterns, in a flexible way. Data from recording of large population of neuron is providing first evidence for these sequences to actually occur in the brain. They even occur during sleep, and other “quiet” times, as a “replay” of past experiences, in a process that may help stabilize and reprocess memories.
However, detecting these replays is very difficult, especially because they may reflect memory for an experience far in the past, or other situations for which it is difficult to form a “template” to search for. Research led by Francesco Battaglia and Martin Vinck (Ernst Strungmann Institute, Frankfurt, Germany) have devised a new mathematical procedure for this. They used a measure based on Optimal Transport theory, a branch of mathematics with applications ranging from economics to computer vision to physics, to define a “distance” between neural patterns, enabling the mapping of these patterns into a geometrical space, so that their structure and regularity can be studied. Initial applications to neural data showed that the method could reconstruct, based on very little extra information, which stimulus an animal was looking at.
A new TOP grant funded by the NWO, Exact Sciences department, will allow the team to explore this idea in much greater depth, by increasing its robustness to noise and other perturbation and considerably increase its applicability. The goal is to characterize the geometry of neural activity, crossing the bridge between very different brain states such as sleep and wakefulness, so that the representations of memory in the brain can be identified and visualized.
The new project, at the boundary between mathematics, computer science and neuroscience will fund 3 new positions at the postdoc/PhD student level, with diverse expertise.
In this opinion article, we propose that the projections originating from the VTA and the LC belong to two distinct systems that enhance memory of novel events. Novel experiences that share some commonality with past ones (‘common novelty’) activate the VTA and promote semantic memory formation via systems memory consolidation. By contrast, experiences that bear only a minimal relationship to past experiences (‘distinct novelty’) activate the LC to trigger strong initial memory consolidation in the hippocampus, resulting in vivid and long-lasting episodic memories.
New information is rarely learned in isolation, instead most of what we experience can be incorporated into previous knowledge networks. However, most rodent laboratory tasks assume the animal to be naive with no previous experience influencing the results, which may be a factor contributing to the current crisis of translational failure when going from the basic lab to human research. Here, we developed a new spatial navigation task, training food locations in a large, gang-way maze the Hex Maze. Analysing both with and across session performance, we can show simple memory effects as well as multiple effects of previous knowledge accelerating both online learning as well as performance increases during offline periods. These effects are reminiscent of both Learning-Set and Schema, two different previous knowledge effects described previously in the literature.
We are currently looking for interesting PhD and PostDoc candidates, preferably with in-vivo electrophysiology and/or data analysis skills. If interested, write to Lisa Genzel with letter of motivation and CV.
Francesco Battaglia and Lisa Genzel receive the 2018 DCN Neurodeveloper fund. With this grant they will collaborate with Noldus Information Technology to develop a closed-loop, automatic sleep deprivation system that will have both an invasive as well as a non-invasive mode.
Our Lisa Genzel has just been awarded a competitive VIDI Grant by the NWO. The Laboratory will soon open 2 positions. Research will aim to investigate the interaction of sleep and novelty in memory consolidation. Electrophysiology and optogenetics will play a key role in understanding the interaction between the Hippocampus and the Prefrontal Cortex. More information here.
M-GATE is a new collaboration funded by a Marie Sklodowska-Curie Action of the European Union. We will host 15 talented young researchers in 8 top European institutions for Memory research. The network is coordinated by Francesco Battaglia. In the Memory Dynamics Lab, we will host three PHD positions, co-supervised by Francesco Battaglia and Lisa Genzel. The emphasis will be on hippocampal/cortical communication and oscillations. We seek candidates with a good quantitative background, interested in combining experimental and theoretical approaches.
Please see the M-GATE website for details on the project