Temporal relationships in grid cell neural networks during input inactivation 1/3

Part 1 of my Master's thesis seminar at the Derdikman Spatial Perception and Memory Lab, Technion Israel Institute of Technology 2017.

part 1    • Temporal relationships in grid cell neural...  
part 2    • Temporal relationships in grid cell neural...  
part 3    • Temporal relationships in grid cell neural...  
Derdikman Lab https://derdiklab.net.technion.ac.il/
Completed paper https://elifesciences.org/articles/47147
Code https://github.com/noamza/GridCellCor...

Grid Cells, a specialized neuron found in the mammalian Medial Entorhinal Cortex (MEC), provide one of the most aesthetic problems in cortical computation. Despite producing a remarkably consistent geometric firing pattern in 2D space, it remains unclear how this pattern is generated. Here we investigate this enigma by looking at extracellular grid cell recordings during hippocampal inactivation. We re-analyzed data from simultaneously recorded grid cells in a hippocampal inactivation experiment (Bonnevie et al., 2013) in which inhibition of the hippocampus led to the disappearance of grid cells. We asked whether the internal dynamics of the grid cell network remained intact despite hippocampal inactivation. By comparing grid cells before and after hippocampal inactivation, we found statistically significant correlations between the firing times of simultaneously recorded grid cells. These correlations remained intact despite hippocampal inactivation and consequent deterioration of spatial firing relationships. We also found a unique subset of grid cells with high head-directional tuning, which did not maintain their temporal correlations after hippocampal inactivation. Our findings support the hypothesis that there exist synchronized network dynamics underlying the grid cell network that do not depend on hippocampal input.