Analysis of trial-by-trial variation in pursuit eye velocity and responses in area MT. (A) Conceptual model of sources of trial-by-trial variation in pursuit and perception. (B) Trial-by-trial correlation of z-scored responses of two MT neurons with a strong noise correlation. (C) Trial-by-trial variation in 17 single-trial examples of the initiation of pursuit. (D) Much smaller trial-by-trial variation shown by the mean and standard deviation of eye velocity during the VOR. (E) Each symbol shows data for a different pair of MT neurons with neuron-neuron noise correlation plotted as a function of the difference between the preferred speeds of the two neurons. (F) Example traces and single trial rasters showing data used to compute MT-pursuit correlations. (G) Each symbol shows MT-pursuit correlation for a single neuron as a function of the target speed relative to preferred speed. Individual neurons appear multiple times for different target speeds. (H) Cartoon graph to illustrate the opposite effects of noise added downstream on behavioral variance and neuron-behavior correlation. Panels are replotted with permission from Lisberger (2010), Huang and Lisberger (2009), and Hohl et al. (2013).