Uncertainty in the hippocampus (360G-Wellcome-212262_Z_18_Z)

Hippocampal neurons are tuned to abstract, behaviourally highly relevant variables, such as the location of the animal (place cells), or particular memories being recalled (memory cells). However, it is unknown how these neurons represent a behaviourally equally important kind of information: the uncertainty about location or memory. Building on recent advances in the neural coding of perceptual uncertainty in neocortical sensory areas, we will develop computational models to study hippocampal population codes for uncertainty in location and memory. These models will unify a diverse set of empirical data, including place field stability and neural oscillations, under a coherent functional account. Moreover, as neocortical findings suggest that response variability may provide crucial clues about the neural coding of uncertainty, we will also make explicit predictions about this almost entirely neglected aspect of hippocampal representations: response variability, and its modulation under conditions associated with different levels of uncertainty. We will test these predictions by conducting novel analyses of hippocampal recordings in rats and humans. Our work will thus reveal how the GPS system of the brain achieves what any truly well-functioning GPS must: to not only represent a single point estimate of location but also the uncertainty about it.