M.Sc Thesis

M.Sc StudentAlmog Noam
SubjectCorrection Structure of Grib Cells is Preserved During
Hippocampal Inactivation
DepartmentDepartment of Medicine
Supervisor ASSOCIATE PROF. Dori Derdikman
Full Thesis textFull thesis text - English Version


Grid cells, found in the mammalian Entorhinal Cortex (EC), provide one of the most aesthetic problems in cortical computation. Despite producing a remarkably consistent hexagonal 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 the grid cells. We ask whether the internal dynamics of the grid cell network remain intact despite hippocampal inactivation. By comparing grid cells before and during 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 patterns. We also analyzed a unique subset of grid cells with high head-directional tuning, and found that, unlike regular grid cells, they 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, and that the network dynamics of conjunctive grid - head direction cells are fundamentally different than those of pure grid cells.