UCLA

How the brain represents space is a long-standing question, whose answer is most likely to be found within the hippocampal formation. There, spatially selective neurons called place cells provide strong evidence that they are able to form relations between elements of the environment and map the position of the animal with respect to them. These cells are modulated by multiple inputs, and their activity patterns both at the neuronal and population change appropriate to the available sensory and motor information. However, the degree of their contributions and the mechanism behind their integration are unclear.

The goal of this thesis is to determine the contribution of these different afferent signals by manipulating the spatial information provided by them in order to shed light on the mechanisms of multisensory integration in the hippocampus. This is difficult, if not impossible, to realize in real world (RW) experiments but virtual reality (VR) has become a popular tool that can be used to achieve this dissociation. In this thesis VR environments are used to manipulate the spatially relevant information provided by visual and locomotion cues and hence determine their contributions to the hippocampal spatial map.

The results described show that distal visual cues alone are insufficient to generate spatially selective activity, but are sufficient to generate activity that is selective to the head-direction of the animal. Additionally, traditionally described spatially selective activity in the form of place fields is not necessary in order to perform a spatial navigation task.