The role of hippocampus in goal and goal value coding
Sujet proposé par
Directeur de thèse:
Unité de recherche UMR 7210 Institut de la Vision
Domaine: Sciences et technologies de l'information et de la communication
At the interface between spatial cognition and decision-making, this project aims at unravelling the role of the hippocampus in spatial goal coding and goal value coding. The hippocampus is a brain structure that has been shown to be involved in episodic memory and spatial cognition. In particular, hippocampal cells show an activity which is highly correlated to a subject’s position in a given environment (O’Keefe and Dostrovsky, 1971). At the population level, these cells are likely to be the support for a “cognitive map”, a representation used to store, organise, and recall information about elements of the environment and the interactions between them (O’Keefe and Nadel, 1978). If such a representation is used for the planning of actions in goal-oriented behaviours, it should contain information about the location of the goals and their respective value. But whether hippocampal cells’ activity is influenced by the existence of spatial goals is still a matter of debate and seems to depend on the experimental paradigm used. Also, the rare studies in which quantitative aspects of the goal were modified (e.g., associated reward amount) provided controversial results (e.g.,Lee et al., 2012; Tabuchi et al., 2003).
As an attempt to clarify the issue of goal and goal value coding in the hippocampus, we will use in vivo electrophysiological recordings in the rat during a goal-oriented spatial task. A first step will be to develop a task compatible with such recordings where aspects of a goal can be altered, such as its location or its value. Moreover, the task should be easily adaptable to a modelling approach, which could eventually be used to get answers from a more theoretical point of view. Once a proper paradigm is chosen, electrophysiological recordings of hippocampal cells will be performed in different reward conditions. This part of the project will be completed in the Laboratory of Cognitive Neuroscience, in Marseille, under the supervision of Dr. Etienne Save. After the data collection phase, a series of analyses will be performed to address the question of goal and goal value encoding by hippocampal cells. This part of the project will be mainly carried out at the Institute of Vision (in Paris), in the Aging in Vision and Action group, under the supervision of Dr. Angelo Arleo.
This project aims at addressing the crucial question of whether the hippocampus is involved in combining space and value information. The answers that will arise from our study may have a major impact on the understanding of spatial cognition and decision-making in animals. The results could also be used in the neuromimetic modelling area, by transposing to artificial agents the mechanisms with which living organisms update and use goal value to perform adaptive behaviour. Last but not least, in the long term, a better understanding of these neural processes might help finding specific therapeutic targets for decision-making and memory disorders in humans such as schizophrenia, depression or addiction. Indeed, the hippocampus might be involved in these pathologies but its precise role still needs to be elucidated (Airan et al., 2007; Behrendt, 2013; Floresco et al., 2009).
Airan, R.D., Meltzer, L.A., Roy, M., Gong, Y., Chen, H., Deisseroth, K., 2007. High-Speed Imaging Reveals Neurophysiological Links to Behavior in an Animal Model of Depression. Science 317, 819–823.
Behrendt, R.-P., 2013. Conscious experience and episodic memory: hippocampus at the crossroads. Front. Psychol. 4, 304.
Floresco, S.B., Zhang, Y., Enomoto, T., 2009.Neural circuits subservingbehavioral flexibility and their relevance to schizophrenia.Behav. Brain Res. 204, 396–409.
Lee, H., Ghim, J.-W., Kim, H., Lee, D., Jung, M., 2012. Hippocampal Neural Correlates for Values of Experienced Events. J. Neurosci. 32, 15053–15065.
O’Keefe, J., Dostrovsky, J., 1971. The hippocampus as a spatial map. Preliminary evidence from unit activity in the freely-moving rat. Brain Res. 34, 171–175.
O’Keefe, J., Nadel, L., 1978. The hippocampus as a cognitive map.Clarendon Press Oxford.
Tabuchi, E., Mulder, A.B., Wiener, S.I., 2003. Reward value invariant place responses and reward site associated activity in hippocampal neurons of behaving rats. Hippocampus 13, 117–132.