Download scientific diagram | classification of grid cells. gray filled circles indicate gridness and firing field modulation index values for 120 from publication: entorhinal cortex receptive. Gridness scores were calculated using standard equations (5,14–16), but we additionally validated that our implementation was highly accurate in distinguishing grid from non grid cells in simulated data (see ‘gridness score implementation’, ‘unit simulation’, ‘log likelihood ratios and classification of units’ and methods figures.
Out of 141 recorded neurons, we identified 20 cells (14%) with a log likelihood ratio of >4.25 deciban (corresponding to a false discovery rate <5%) in favor of cells with spatially structured firing fields according to the two criteria of modulation index and gridness score. cells classified as grid cells had a lower mean firing rate (0.47 hz. A, room coverage by fields of 3d grid cells (red) and non grid multifield cells (blue; cell classification based on spike shuffling).shown are field positions (pooled and sorted; number of fields. The majority of our grid cells possessed a coefficient of variation (cv; sd divided by mean) larger than 0.5 (58.2% of cells, n = 209 359; mean value of 0.579 ± 0.013; figure 1 b; we stress here that the cv is used here to measure variability of individual firing field rates). figure 1. Crosses show results for 10 randomly generated spike maps with noise on field locations applied only on the east side. filled circles indicate the mean over 10 realizations. e) spike locations of two example cells recorded in a rat that explored the northern and southern half of a box. the two halves are separated by a wall (dashed gray line).
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