Grid cells and place cells – navigating an uncertain world

Abstract: 

The hippocampal formation is necessary for the creation and maintenance of spatial and episodic memories. Hippocampal damage produces dense amnesia as well as severe impairments in the ability to recognise and navigate through space. Electrophysiological recordings made from animals revealed some of the neural mechanisms that support these functions. Place cells, neurons with spatially modulated firing were identified in the rodent hippocampus. 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.

First, I will describe experimental work showing how grid cells and place cells are recruited during replay events – transient periods of non-local activity. Further, how replay trajectories are modulated by the ongoing task demands and contribute to the successful completion of a simple spatial memory task. Second, I will present computational and experimental results indicating that in animals and humans the grid cell representation dynamically adapts to counter spatial uncertainty. Suggesting that the alignment of grid patterns interacts meaningfully with an animal’s sensory environment and that the grid cell system attempts to optimise that interaction. Finally, I will present preliminary work describing how we have applied deep learning techniques to decode spatial information from both rodent and human data.

Further information: ion.fil.brainmeetings@ucl.ac.uk