Role of the hippocampus in goal representation : Insights from behavioural and electrophysiological approaches

The hippocampus plays an important role in spatial cognition, as supported by the location-specific firing of hippocampal place cells. In random foraging tasks, each place cell fires at a specific position (‘place field’) while other hippocampal pyramidal neurons remain silent. A recent study evidenced a reliable extra-field activity in most CA1 place cells of rats waiting for reward delivery in an uncued goal zone. While the location-specific activity of place cells is thought to underlie a flexible representation of space, the nature of this goal-related signal remains unclear. To test whether hippocampal goal-related activity reflects a representation of goal location or a reward-related signal, we designed a two-goal navigation task in which rats were free to choose between two uncued spatial goals to receive a reward. The magnitude of reward associated to each goal zone was modulated, therefore changing the goal value. We recorded CA1 and CA3 unit activity from rats performing this task. Behaviourally, rats were able to remember each goal location and flexibly adapt their choices to goal values. Electrophysiological data showed that a large majority of CA1-CA3 place and silent cells expressed goal-related activity. This activity was independent from goal value and rats’ behavioural choices. Importantly, a large proportion of cells expressed a goal-related activity at one goal zone only. Altogether, our findings suggest that the hippocampus processes and stores relevant information about the spatial characteristics of the goal. This goal representation could be used in cooperation with structures involved in decision-making to optimise goal-directed navigation

Adventures and misadventures of a beautiful international convention

Cécile Duvelle fue Secretaria de la Convención de la UNESCO para la Salvaguardia del Patrimonio Cultural Inmaterial de 2008 a 2015. Texto original en francés traducido por Susana Irigaray Soto, Directora del Museo etnológico de Navarra.Si bien nadie cuestiona seriamente los principios de una Convención internacional que pretende salvaguardar el Patrimonio Cultural Inmaterial, y eso a pesar de las dudas que presidieron su elaboración, los diez primeros años de trayectoria demuestran que la Convención no ha encontrado todavía su “zona de confort”. Más allá de los objetivos de salvaguardia o de la posición central que ha dado a las comunidades portadoras en el proceso de identificación y de salvaguardia, quedan muchas dificultades a nivel internacional, especialmente en lo que se refiere a las inscripciones en las listas indicativas, cosa que ilustra bien cómo la propia gestión de la Convención y también los procesos de candidatura e inscripción, así como la utilización de las listas pueden, a veces, apartarse del espíritu mismo de este instrumento normativo que, sin embargo, ha abierto un horizonte nuevo, renovador, en el discurso patrimonial.While the principle of an international convention to safeguard the intangible cultural heritage is no longer seriously challenged by anyone, despite the hesitations that led to its elaboration, the first ten years of its implementation has yet to find its ‘comfort’ position. Beyond the safeguarding objectives and the centrality of communities of practitioners in the process of identification and safeguarding, there are still many difficulties in the implementation of the Convention. The article focuses mainly on international implementation, particularly inscriptions on the lists, illustrating how the governance of the Convention, as well as the nomination and inscription process and the use of lists sometimes run the risk of deviating from the very spirit of this normative instrument, which has opened up a new and highly innovative horizon in heritage discourse

A boundary vector cell model of place field repetition

Hippocampal place cells are thought to form the neural substrate of a global cognitive map. However, in multicompartment mazes these cells exhibit locally repeating representations, undermining the global cognitive map view of place cells. This phenomenon appears to be related to the repetitive layout of these mazes, but still no hypothesis adequately explains it. Here, we use a boundary vector cell model of place cell firing to model the activity of place cells in numerous multicompartment environments. The activity of modelled place cells bears a striking resemblance to experimental data, replicating virtually every major experimental result. Our results support the boundary vector cell model and indicate that locally repeating place cell firing could result purely from local geometry

Bilan et perspectives de la Convention dans le contexte actuel

Les inscriptions, partie émergée de l’iceberg Avec 145 États ayant ratifié la Convention pour la sauvegarde du patrimoine culturel immatériel en moins de dix ans (il aura fallu vingt-trois ans à la Convention du patrimoine mondial pour compter le même nombre d’États parties), on peut considérer que cette dernière a remporté un franc succès, et ce dans toutes les régions du monde. Rien n’était moins sûr si l’on s’était fié aux débats ayant présidé son adoption par la Conférence générale de l’U..

Social Spaces: Place Cells Represent the Locations of Others

How does the brain represent the location of others? Recordings in rats and bats show that, along with representing self-location in an environment, some hippocampal neurons are modulated by the position of another individual

Volumetric spatial behaviour in rats reveals the anisotropic organisation of navigation

We investigated how access to the vertical dimension influences the natural exploratory and foraging behaviour of rats. Using high-accuracy three-dimensional tracking of position in two- and three-dimensional environments, we sought to determine (i) how rats navigated through the environments with respect to gravity, (ii) where rats chose to form their home bases in volumetric space, and (iii) how they navigated to and from these home bases. To evaluate how horizontal biases may affect these behaviours, we compared a 3D maze where animals preferred to move horizontally to a different 3D configuration where all axes were equally energetically costly to traverse. Additionally, we compared home base formation in two-dimensional arenas with and without walls to the three-dimensional climbing mazes. We report that many behaviours exhibited by rats in horizontal spaces naturally extend to fully volumetric ones, such as home base formation and foraging excursions. We also provide further evidence for the strong differentiation of the horizontal and vertical axes: rats showed a horizontal movement bias, they formed home bases mainly in the bottom layers of both mazes and they generally solved the vertical component of return trajectories before and faster than the horizontal component. We explain the bias towards horizontal movements in terms of energy conservation, while the locations of home bases are explained from an information gathering view as a method for correcting self-localisation

A boundary vector cell model of place field repetition

Hippocampal place cells are thought to form the neural substrate of a global cognitive map. However, in multicompartment mazes, these cells exhibit locally repeating representations, undermining the global cognitive map view of place cells. This phenomenon appears to be related to the repetitive layout of these mazes, but still no hypothesis adequately explains it. Here, we use a boundary vector cell (BVC) model of place cell firing to model the activity of place cells in numerous multicompartment environments. The activity of modeled place cells bears a striking resemblance to experimental data, replicating virtually every major experimental result. Our results support the BVC model and indicate that locally repeating place cell firing could result purely from local geometry

Field repetition and local mapping in the hippocampus and medial entorhinal cortex

Hippocampal place cells support spatial cognition and are thought to form the neural substrate of a global 'cognitive map'. A widely held view is that parts of the hippocampus also underlie the ability to separate patterns, or to provide different neural codes for distinct environments. However, a number of studies have shown that in environments composed of multiple, repeating compartments, place cells and other spatially modulated neurons show the same activity in each local area. This repetition of firing fields may reflect pattern completion, and may make it difficult for animals to distinguish similar local environments. In this review we will (a) highlight some of the navigation difficulties encountered by humans in repetitive environments, (b) summarise literature demonstrating that place and grid cells represent local and not global space, and (c) attempt to explain the origin of these phenomena. We argue that the repetition of firing fields can be a useful tool for understanding of the relationship between grid cells in the entorhinal cortex and place cells in the hippocampus, the spatial inputs shared by these cells, and the propagation of spatially-related signals through these structures

Insensitivity of place cells to the value of spatial goals in a two-choice flexible navigation task

Hippocampal place cells show position-specific activity, thought to reflect a self-localization signal. Several reports also point to some form of goal encoding by place cells. We investigated this by asking whether they also encode the value of spatial goals, which is a crucial information for optimizing goal-directed navigation. We used a continuous place navigation task in which male rats navigate to one of two (freely chosen) unmarked locations and wait, triggering the release of reward which is then located and consumed elsewhere. This allows sampling of place fields, and dissociates spatial goal from reward consumption. The two goals varied in the amount of reward provided, allowing assessment of whether the rats factored goal value into their navigational choice, and of possible neural correlates of this value. Rats successfully learned the task, indicating goal localization, and they preferred higher-value goals, indicating processing of goal value. Replicating previous findings, there was goal-related activity in the out-of-field firing of CA1 place cells, with a ramping-up of firing rate during the waiting period, but no general over-representation of goals by place fields, an observation that we extended to CA3 place cells. Importantly, place cells were not modulated by goal value. This suggests that dorsal hippocampal place cells encode space independently of its associated value, despite the effect of that value on spatial behavior. Our findings are consistent with a model of place cells in which they provide a spontaneously constructed value-free spatial representation, rather than encoding other navigationally relevant, but non-spatial, information

Hippocampal place cells encode global location but not connectivity in a complex space

Flexible navigation relies on a cognitive map of space, thought to be implemented by hippocampal place cells: neurons that exhibit location-specific firing. In connected environments, optimal navigation requires keeping track of one’s location and of the available connections between subspaces. We examined whether the dorsal CA1 place cells of rats encode environmental connectivity in four geometrically identical boxes arranged in a square. Rats moved between boxes by pushing saloon-type doors that could be locked in one or both directions. Although rats demonstrated knowledge of environmental connectivity, their place cells did not respond to connectivity changes, nor did they represent doorways differently from other locations. Place cells coded location in a global reference frame, with a different map for each box and minimal repetitive fields despite the repetitive geometry. These results suggest that CA1 place cells provide a spatial map that does not explicitly include connectivity