Event:

For several decades the hippocampal formation has been identified as a necessary component for the creation and maintenance of spatial and episodic memories. Damage to the hippocampus and neighbouring structures leads to dense amnesia as well as severe impairments in the ability to recognise, imagine and navigate through space. Electrophysiological recordings made from animals and humans have revealed some of the neural mechanisms that support these functions. In the 1970s, place cells, neurons with spatially modulated firing were identified in the rodent hippocampus by John O’Keefe. More recently grid cells, with multiple spatial firing fields tessellated in a hexagonal array, were discovered in the entorhinal cortex. Despite considerable attention it is still unclear how this neural machinery is engaged during navigation and more generally in mnemonic function. I will describe computational and experimental work showing how grid cell networks can be used to drive goal directed navigation. I will present data showing how grid representations of separate spaces become combined into a single global representation; allowing navigation across large scale space. Finally, I will discuss new results showing how grid cells participate in "replay" events; a phenomenon which has previously been observed for place cells, during which the activity of spatial cells rehearse routes through the animal’s environment. Taken together these results suggest grid cells are at the centre of a network required for planning goal directed behaviours and processing spatial memories.