CA1

Behavioral time scale synaptic plasticity underlies CA1 place fields

Measurements from hippocampal place cells in small enclosures have led to a classical view of highly stereotyped neural tuning functions with smooth, unimodal tuning fields that uniformly tile the environment. However, recent experiments conducted in large spaces across multiple species have revealed a much more irregular neural code than suggested by the classical view. Indeed, place cells in large environments typically fire in multiple locations, and the multiple firing fields of individual cells, as well as those of the entire population, vary considerably in size and shape. We recently sh

Cognitive maps are mental representations of spatial and conceptual relationships in an environment. The hippocampus, a key brain region for these maps, exhibits neural population activity that often evolves along nonlinear, low-dimensional manifolds. While cognitive maps have been characterized at the level of cell tunings to spatial location and decorrelations over time, a precise, unsupervised, and quantitative model of how this map forms and morphs at the population level remains elusive due to the large dimensionality and nonlinearity of neural activity. Current dimensionality reduction t

…from thousands of neurons in the CA1 region of the hippocampus while mice learned to efficiently collect rewards from two subtly different linear tracks in virtual reality. The results provide a de

Hippocampal studies provide a rich window into the mechanisms of memory via the paradigm of spatial navigation. To interpret neural responses, it is common practice to first build encoding models using position during locomotion as the label, and then decode the position using this model. Of particular interest is the mismatch between the decoded and the actual position, for instance, replay of non-local trajectories during rest. However, it is unclear whether a priori chosen labels explain neural data the best. By imposing spatial structure to times of immobility, we may be systematically mis

Understanding the mechanisms of statistical learning, where organisms infer structure from sensory observations without explicit instruction, is crucial in comprehending how the brain processes and responds to complex and dynamic environments. This work explores the innate capabilities of mice to discern environmental regularities, focusing on the role of the hippocampus in this unsupervised learning process. The study leverages a novel comparative behavioural paradigm, termed X-detection, to manipulate the statistics of embedded tone sequences (patterns) in an auditory cover task: subjects s

…Specifically, neurons in the CA1 area of the hippocampus have been shown to represent variables such as cue configurations and their order in space and time. To investigate the

…We performed calcium imaging in CA1 place cells using a new Uncertain Reward virtual reality Task (URTask), in which mice run along a linear track and

…imaging data recorded from mouse CA1 during free foraging in a two-dimensional arena with the help of a miniature

Neuronal diversity in the cortex is the largest amongst GABAergic neurons. In the hippocampus, GABAergic cells have been sorted in several groups based on their morphology, firing patterns, connectivity, molecular profiling, and RNA content. Identification and manipulation of these neuron types is a prerequisite to deciphering their role in circuit dynamics, behavior, and the computational mechanisms of the cortical networks they are embedded in. We first grouped the virtual totality of GABAergic neurons into four major families. Parvalbumin-expressing neurons, Somatostatin-expressing neurons,

…Those found in the subregion CA1 possess plastic synapses and are very sensitive to e

…is found in CA2, the lowest - in CA1 (the most and the least resistant regions, respectively). The aim of my study was therefore to assess cell ty

…Neural populations in CA1 exert influence on navigational outcomes, but this coupling makes it challenging to isolate abstract representations of travel from concrete motor actions. In this work, we present an experimental paradigm that uses a hippocampal closed-loop Brain-Machine Interface (BMI) to decouple running locomotion from the cognitive map. This BMI associates neural activity with locations on a 1D Virtual Reality (VR) track, and then translates those locations into contextually appropriate actions (Fig

…Electrophysiological recordings from CA1 pyramidal cells demonstrate that hM4Di does not mediate hyperpolarization or shunting and, i

…(BTSP), recently described in mouse CA1PCs, is a putative mechanism of PF formation (Bittner et al., 2015). It starts with a silent PC exhibiting a large Ca2+ plateau in dendrites accompanied by somatic bursting, which initiates the emergence of tuning near the location of induction. Consequently, activity is strongest during formation and lower

…information, while subregion CA1 encodes more generalized information.The free-energy principle entails that neural networks with more generalized representations operate closer to criticality, where external

…SCOP dynamics in the hippocampal CA1 in nocturnal mice. Whether diurnal changes

…synthesis in hippocampal neurons in CA1, enabling dopamine-dependent long-term potentiation (DA-LTP). Neuronal activity is required for the dopamine-induced increase in protein synthesis, and we found that DA-LTP is mediated by t

Spatial navigation impairments are among the earliest clinical manifestations of Alzheimer’s Disease (AD). Pyramidal cells of the hippocampus fire selectively when the animal is in a specific location in the environment, leading to the theory that the hippocampus plays a crucial role in forming a cognitive map of the environment. The phenomenon of “remapping”, where specific cells exhibit selective firing in distinct environments, is thought to support the formation of different memories. By performing in-vivo electrophysiological recordings in freely moving mice while they navigate through di

The G-protein coupled receptor GABAB is an important regulator of presynaptic neurotransmitter release and postsynaptic excitability. In anti-GABABR autoimmune encephalitis pathogenic autoantibodies (aAB) target the GABAB receptor, leading to various symptoms, including epilepsy, cognitive disorders, and short-term memory loss. Here we aimed at evaluating the influence of these aAB on hippocampal-dependent cognitive and epileptic pathways. We used purified patient-derived antibodies (control- and anti-GABABR-IgG) in a chronic mouse model of the disease to evaluate the memory formation via Nove

Immunoglobulins are the first line of defense against pathogens and, as such, it is widely assumed that they are exclusively expressed by B lymphocytes. In a recent study comparing the translatomes of spinal neuron subtypes, we obtained evidence indicating the presence of neuron specific Ighm transcripts encoding only the constant (Fc) but not the variable regions of IgM, in the central nervous system (CNS) of mice. Using in situ hybridization we confirmed prominent expression of Ighm in the spinal cord and found expression in several other CNS areas e.g. deep cortical layers and the hippocamp

Sociability is an extremely complex behavior that requires the involvement and coordination of different brain areas. The hypothalamic neuropeptide oxytocin (OT) plays a pivotal role in regulating various aspects of social behavior and can reach and modulate many regions of the central nervous system. However, the mechanisms through which it modulates neuronal activity are still unclear, also because this peptide can exert different effects depending on the brain area and on the neuronal type. In this work, we investigated and deepened the action of OT on a specific subpopulation of interneuro

…recordings from hippocampal area CA1 in horizontal mouse brain slices. We found that a spontaneously occurring hippo

Depression affects 20% of the general population and is a leading cause of disability worldwide, with one third of patients presenting treatment-resistant depression (TRD). Subanesthetic ketamine is a promising rapid-acting TRD pharmacotherapy, but optimal treatment frequency remains unclear. The present study aims to better understand the effects of an acute (single dose) and chronic (one week daily) 10mg/kg ketamine treatment on hippocampal plasticity, a key mechanism impaired in depression, in a putative TRD model: the Wistar-Kyoto (WKY) rat exposed to chronic mild stress (CMS). Rats were e