This proposal will address how a multimodal cognitive system, the neural representation of space in the hippocampus, emerges during development. There is a long tradition in neuroscience of studying the development of primary sensory systems, but fewer studies have concentrated on the development of brain networks supporting higher-order cognitive representations.
Our recent findings (Wills, Cacucci et al. Science, 2010) provide a starting point to fill this gap, charting the emergence of spatial responses of hippocampal formation neurons, using in vivo recording in awake, behaving rats.
The hippocampal formation supports neural representations of the environment ('cognitive maps') by means of which an animal can locate itself and navigate to a goal location. It contains three classes of spatially-tuned cells: place cells, which code for location, head direction cells, which code for directional orientation and grid cells, which may code for distance travelled.
The key aim of this proposal is to delineate the developmental processes that create this neural representation of space, focusing on the representations of place and direction.
We will delineate which sensory information is capable of driving spatial firing, and whether early hippocampal coding is truly spatial in the sense of representing configurations of stimuli and not single cues. How are abstract spatial constructs (place and head direction) built from raw sensory information during development? We will test whether boundary sensitive neurons and angular velocity tuned neurons are the elemental 'building blocks' making up place and directional signals, as suggested by many theoretical models.
We will also investigate the role of experience in the construction of spatial representations. Do the network architectures underlying spatial firing emerge through experience-dependent learning mechanisms, or are they the result of self-organizing processes which take place independently of experience?
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