p587fig16.17 A finer analysis of the 2D trigonometry of spatial navigation showed that both the frequency and amplitude of coactivations by stripe cells determine the learning of hexagonal grid fields.<BR>||  A refined analysis: SOM amplifies most frequent and energetic coactivations (Pilly, Grossberg 2012).  [linear track, 2D environment]. (left) Stripe fields separated by 90°. 25 coactivations by 2 inputs.  (right) Stripe fields separated by 60°. 23 coactivations by 3 inputs.