Lisa Genzel, Evelien Schut, Tim Schröder, Ronny Eichler, Mehdi Khamassi, Angela Gomez, Irene Navarro Lobato, Francesco Battaglia
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. Rodents are exposed to multiple sample trials, in which they explore objects in specific spatial arrangements, with object identity changing from trial to trial. Here, we could show that both mice and rats can accumulate information across multiple trials and express a long-term abstracted memory.
Adrian J. Duszkiewicz, Colin G. McNamara, Tomonori Takeuchi and Lisa Genzel
Adaptation to the ever-changing world is critical for survival, and our brains are particularly tuned to remember events that differ from previous experiences. Novel experiences induce dopamine release in the hippocampus, a process which promotes memory persistence. While axons from the ventral tegmental area (VTA) were generally thought to be the exclusive source of hippocampal dopamine, recent studies have demonstrated that noradrenergic neurons in the locus coeruleus (LC) corelease noradrenaline and dopamine in the hippocampus and that their dopamine release boosts memory retention as well. 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. [PDF]
Levan Bokeria, Ronny Eichler, Lisann Brincker, Alejandra Alonso, Anumita Samanta, Matteo Guardamagna, Patrick Spooner, Francesco Battaglia, Lisa Genzel
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.
N. Müller, S. Campbell, M. Nonaka, T.M. Rost, G. Pipa, B.N. Konrad, A. Steiger, M. Czisch, G. Fernández, M. Dresler, L. Genzel
Variance in spatial abilities are thought to be determined by in utero levels of testosterone and estrogen, measurable in adults by the length ratio of the 2nd and 4th digit (2D:4D). We confirmed the relationship between 2D:4D and spatial performance using rats in two different tasks (paired-associate task and watermaze) and replicated this in humans. We further clarified anatomical and functional brain correlates of the association between 2D:4D and spatial performance in human
Irene Navarro-Lobato, Lisa Genzel
Alternations of up and down can be seen across many different levels during sleep. Neural firing-rates, synaptic markers, molecular pathways, and gene expression all show differential up and down regulation across brain areas and sleep stages. And also the hallmarks of sleep – sleep stage specific oscillations – are characterized themselves by up and down as seen within the slow oscillation or theta cycles. In this review, we summarize the up and down of sleep covering molecules to electrophysiology and present different theories how this up and down could be regulated by the up and down of sleep oscillations.
Lukas Grossberger, Francesco P. Battaglia and Martin Vinck
Temporally ordered multi-neuron patterns likely encode information in the brain. We introduce an unsupervised method, SPOTDisClust (Spike Pattern Optimal Transport Dissimilarity Clustering), for their detection from high-dimensional neural ensembles. Our method handles efficiently the additional information from increasingly large neuronal ensembles and can detect a number of patterns that far exceeds the number of recorded neurons.
Lisa Genzel, Evelien Schut, Tim Schroeder, Ronny Eichler, Gulberk Bayraktar, Nikkie Cornelisse, Hussein Gareth, Federico Giuliani, Angela Gomez, Sidney Hulzebos, Joanne Igoli, Stefanos Loizou, Irene Navarro Lobato, Luc Nijssen, Luca Reinik, Olaf Stoutjedijk, Minou Verheag, Francesco Battaglia
An important aspect of a memory is whether it is representing a specific event or whether it is a representation of knowledge extracted over multiple episodes. To investigate this difference, we developed a new multi-trial behavioral task that can assess memory accumulation in rodents
Lisa Genzel and Francesco Battaglia
Memory is made up of multiple interacting systems, intervening at different times during the lifetime of the memory, and organizing information in different ways. We review here some of the experimental evidence on memory replay and dynamical interactions between cortex and hippocampus during sleep, with a focus on the prefrontal cortex, one of the key cortical areas for memory.
Lisa Genzel, Marijn Kroes, Martin Dresler, Francesco Battaglia
Sleep is strongly involved in memory consolidation, but its role remains unclear. Here, we reconcile these theories by highlighting the distinction between light and deep nonrapid eye movement (NREM) sleep. Specifically, we draw on recent studies to suggest a link between light NREM and active potentiation, and between deep NREM and homeostatic regulation. This framework could serve as a key for interpreting the physiology of sleep stages and reconciling inconsistencies in terminology in this field.