Topic: spatial information

Applying information theoretic measures to neuronal activity data enables the quantification of neuronal encoding quality. However, when the sample size is limited, a naïve estimation of information typically contains an upward bias, which may lead to misinterpretation of coding characteristics. This bias is exacerbated in Ca2+ imaging because of the temporal sparsity of detected Ca2+ signals. Here, we introduce methods to correct the bias in the naïve estimation of information from limited sample sizes and temporally sparse activity. We demonstrate the higher accuracy of our methods over prev

Sequential reactivation (replay) of neurons in the hippocampus has been widely observed in sharp wave ripple events (SWRs) during awake and sleep periods, and they are associated with mnemonic processes, such as memory retrieval, consolidation, future planning and decision making. Previous studies have shown that the replay trajectories in the rat hippocampus are rather random, which resemble at least two different types of stochastic process, one corresponding to Brownian diffusion discovered during sleep SWRs and the other Lévy superdiffusion discovered during awake SWRs. The underlying mech

Hippocampal cells show precise spatial tuning to the animal's position during behavior. During stopping periods, the hippocampus encodes spatially coherent trajectories through the environment called replays that resemble the animal's behavior. Replay has been proposed as a form of virtual experience that supplements real experience for the purposes of learning and planning. However, it is unknown whether the precise spatial tuning of place cells as a function of animal position is preserved as a function of encoded replay position, independent of the animal's location. This is far from obviou

Navigation occurs through a continuum of space and time. The hippocampus is known to encode the immediate position of moving animals. However, active navigation, especially at high speeds, may require representing navigational information beyond the present moment. Using wireless electrophysiological recordings in freely flying bats we demonstrate that neural activity in area CA1 predominantly encodes nonlocal spatial information up to meters away from the bat’s present position. This spatiotemporal representation extends both forward and backwards in time with an emphasis on future locations

The hippocampus is presumably involved in spatial navigation, the formation of long-term memories in mammals, and the construction of a cognitive map of space using a prominent feature – place cells [1] (PCs). It is unclear how PCs’ neural codes are related to memory: turnover of neural representations could be involved in learning, while codes’ stability may support long-term storage and retrieval of memories [2]. In this work, we focus on the analysis of one-photon (1P) calcium imaging data recorded from mouse CA1 during free foraging in a two-dimensional arena with the help of a miniature

Since their introduction as a theoretical concept in the 70es by Amari, ring attractor networks have been a popular tool to explain orientation and space dependence of neural activity. Only recently, there has been an experimental proof that they are actually implemented in the fly's brain (Kim et al. 2017). While these kind of networks are useful to model systems representing only one map, like head-direction systems for example, there is a multitude of maps stored in the hippocampus (cf. panel a of the figure). This extension is taken into account by continuous attractor neural networks (CAN

Hippocampal circuits form the basis of navigational cognitive maps. Yet spatial information alone is not enough to build a useful map, context cues need to be embedded in it. While the encoding of spatial information in the hippocampus is well-established and place cells, border cells and others have been identified, the precise representational strategies of valence information remain elusive. Here, we study how learning combines spatial and affective knowledge in the population activity of ventral-to-dorsal (valence-tuned) and dorsal-to-dorsal (space-tuned) pathways in the CA3 region. Do inc

A growing body of evidence indicates a functional dichotomy between the dorsal (dHC) and ventral poles of the hippocampus (vHC). Specifically, the dorsal region is implicated in encoding spatial information and episodic memories, whereas the ventral region is recognized for its role in processing the emotional aspects associated with those memories. The medial septum/diagonal band of Broca complex (MSDB) plays pivotal role in both cognitive and emotional functions, implying anatomically distinct pathways of MSDB efferents conducting information to dHC and vHC, respectively. To test this, we tr

Blindness significantly impacts the ability to acquire spatial information and build a cognitive map to stay oriented in the environment. Possible consequences include reduced autonomy, increased anxiety, social isolation, and overall decreased quality of life. It is therefore important to investigate non-visual cognitive map formation and its underlying neural mechanisms, which are still poorly understood. Therefore, we used fMRI to study the neural correlates of cognitive map formation through touch and audition in individuals with congenital and acquired blindness, and sighted individuals a

Remembering the context in which an aversive experience occurred is critical to safely navigating the environment. The hippocampus (HPC) has been implicated in the encoding of spatial information through the presence of place cells (PC) which are tuned to specific locations in space. As a population, PCs form a “cognitive map” of the environment that adapts to contextual changes through remapping. The dorsal and ventral parts of the hippocampus have different functional implications in spatial coding. While the dorsal HPC mainly processes spatial information, the ventral HPC encodes valence an

Standard models of episodic memory emphasise that parallel streams of spatial information, arriving from medial entorhinal cortex (MEC), and object information, arriving from lateral entorhinal cortex (LEC), are integrated within the hippocampus. However, we recently discovered that fan cells in the LEC send direct projections to MEC, suggesting that spatial and object information could be integrated within MEC (Vandrey et al. 2022, doi:10.7554/eLife.83008). Evidence for object-related firing in the MEC is consistent with this possibility, but whether LEC projections influence spatial and obje

The aim of this project is to characterize how grid cells code spatial information during goal-directed navigation. Previous studies on the effect of goal on grid cells activity merged goal location with reward, making difficult to conclude about the nature of the information (i.e. location or reward) integrated by the grid cells network. We used a continuous-goal directed navigation task which allows separating spatial goal from the reward. We found a local distortion of the grid map around the goal that only emerges when a halt inside the goal zone is required to obtain the reward. This indi

To understand how amyloidosis in Alzheimer’s Disease changes circuit properties affecting memory encoding and recall, we examined the relationship between neuronal activity, nearness to amyloid plaques, and spatial memory readout from hippocampal CA1 place cells. We performed two-photon calcium imaging in head-fixed 5xFAD mice navigating an air-lifted circular track. Neuronal hyperactivity in CA1 during non-running periods was higher in 5xFAD mice compared to wildtype littermates in both young (2-3 months) and old (6.5-10 months) groups. Moreover, neurons close to amyloid plaques (<20µm in