Extended Data Fig. 3: Ellipticity of object-vector fields.
To more formally characterize the firing of object-vector cells, we compared two models of vector-determined firing, with firing fields corresponding to a Gaussian circle or an ellipse. The models were applied to the raw, unsmoothed firing rate maps. a, A slightly better fit is usually obtained from the elliptic model. Left to right: (1) path plot of an object-vector cell; (2) unsmoothed firing rate map of the cell; (3) object-vector field obtained by fitting an elliptic model to the raw unsmoothed firing rate map of the cell; and (4) object-vector field obtained by fitting a Gaussian model to the raw unsmoothed firing rate map. For this cell, the elliptic fit explained 3.2% more of the underlying data (the unsmoothed firing rate map) than the Gaussian circle model. b, Left, frequency distributions showing relative goodness of fit (see Methods) of the elliptic and circular models. Right, aspect ratio (ratios between s.d. values in two dimensions) for all object-vector cells. Aspect ratios for the best fit had a median of 1.6 and 25th–75th percentiles of 1.3–2.0. An aspect ratio near 1 indicates that the firing field is almost circular.
