Hippocampal place cells

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

…the spatial coding properties of hippocampal place cells and entorhinal grid cells. However, the diverse, spatially-tuned cells of the primary output of hippocampal neurons - the subiculum - have eluded a unified account. Here, we demonstrate that incorporating rodent behavioural biases into the successor representation reproduces the heterogeneous activity patterns of subicular neurons. Notably, this framework accounts for boundary vector and corner cells; neuronal types that are absent from upstream hippocampal re

…of the well-known spatial remapping of hippocampal place cells in the face of environmental change to interrogate these processes. 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

…discovery by Scoville and Milner that hippocampal damage causes profound and persistent amnesia and the discovery by O’Keefe and Dostrovsky of hippocampal place cells in rodents. However, it has been unclear to what extent spatial representations are present in the primate brain and how to reconcile these representations with the known mnemonic function of this region. I will discuss a series of experiments that have examined neural activity in the hippocampus in monkeys performing behavioral tasks including

Recent research involving bats navigating lengthy tunnels has confirmed that hippocampal place cells can be active at multiple locations, with considerable variability in place field size and peak rate. In a recurrent networks, such variability implies quenched disorder in the synaptic weights, impeding the establishment of a continuous manifold of fixed points. If most positions in space are not any longer fixed points, is the popular notion of continuous attractors still relevant? What would be the neural dynamics underlying retrieval of spatial representations?We study the dynamics of recur

…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

Abundant work has highlighted the functional role of the hippocampal formation in navigation behaviour across species. Recent studies highlight evidence that the same neural coding mechanisms found to underly the representation of physical spaces also apply to conceptual domains. Specifically, the representation of locations in both physical and conceptual spaces is reflected in distinct neural activity patterns in hippocampus and entorhinal cortex. Electrophysiological work from rodents has shown that single hippocampal place cells represent different locations in different spaces – a functio

During spatial navigation, hippocampal place cells rely on visual inputs to map space, but other sensory modalities, such as odour, can also be effectively used (doi: 10.1093/cercor/bht239). Although rodents are nocturnal and short-sighted, little is known about the role of other sensory modalities as substrates for place fields. Here, we recorded electrophysiologically from place cells in the hippocampal CA1 region of adult male rats while they explored a round empty field arena in darkness and in the absence of reliable tactile, olfactory, and visual cues. We compared place cell behaviour un

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

Although hippocampal place cells prominently "replay" nonlocal trajectories, the computational function of these events remains elusive. One hypothesis holds that replay plans routes to current goals by propagating information about rewards over space. An alternative view contends that replay learns and maintains routes more generally, separate from current goals or plans, to update a "cognitive map". The former view has been formalized in a reinforcement learning framework (Mattar and Daw, 2018), which predicts which trajectories should be replayed preferentially ("prioritized") to support pl

…Specifically, in the hippocampus, place cell ensembles are spontaneously replayed in sequences corresponding to trajectories of the animal in previously visited environments1. In parallel, head-direction cells of the anterodorsal thalamic nucleus which fire for a specific direction of the animal’s head, remain coordinated during sleep. The HD signal is crucial for spatial navigation and the anterior thalamus is necess

Neural responses are variable: even under identical experimental conditions, single neuron and population responses typically differ from trial to trial and across time. Recent work demonstrated that this variability can be modulated by specific stimulus features, most prominently quenched by stimulus onset. However, it is unknown how ubiquitous this effect is across stimulus features, and indeed whether it exists in brain areas to which classical neural coding approaches cannot be applied due to the lack of trials with repeatable experimental stimuli. To address these questions, we develop a

…those in the brain, for instance place and grid cells of the medial temporal lobe. Here we ask if combining ongoing predictive learning of sensory events and of notional value of actions leading to rewards forms representations that enable more efficient goal-directed learning than reinforcement learning alone. Si

…in 2014 for his “discoveries of cells that constitute a positioning system in the brain". His revolutionary research on hippocampal place cells provided deeper insight into the neural processes underlying the sense of space. His lab in Sainsbury Wellcome Centre applies a wide range of methods to facilitate our understanding of the role of the entorhinal cortex and hippocampus in spatial memory and the neural mechanisms underlying short-term memories in the amygdala.