What the NYT article omits is that a triangular grid [1] encoded by the grid cells is used to track movement, according to Wikipedia's entry for Grid cell. [2]

What the NYT article omits is that a triangular grid [1] encoded by the grid cells is used to track movement, according to Wikipedia's entry for Grid cell. [2] Further questions: How many grid cells are there? What is the largest area that can be fully represented? How are grid cells reused as the subject travels? [1] https://twitter.com/th222/status/364156774309314560 https://twitter.com/th222/status/364156774309314560 [2] http://en.wikipedia.org/wiki/Grid_cell http://en.wikipedia.org/wiki/Grid_cell