Global motion integration in the cat's lateral posterior-pulvinar complex

Our laboratory previously showed that thalamic neurons in an extrageniculat e nucleus, the lateral posterior-pulvinar complex (LP-pulvinar) could perfo rm higher-order neuronal operations that had until then only been attribute d to higher-level cortical areas. To further assess the role of the thalamu s in the analysis of complex percepts, we have investigated whether neurons in the LP-pulvinar complex can signal the direction of motion of random-do t kinematograms wherein the individual elements of the pattern do not provi de coherent motion cues. Our results indicate that a subset of LP-pulvinar cells can integrate the displacement of individual elements into a global m otion percept and that their large receptive fields permit the integration of motion for elements separated by large spatial intervals. We also found that almost all of the global motion-sensitive neurons were not systematica lly pattern-motion-selective when tested with plaid patterns. The results i ndicate that LP-pulvinar cells can perform the higher-level spatio-temporal integration required to detect the global displacement of objects in a com plex visual scene, further supporting the notion that extrageniculate thala mic cells are involved in higher-order motion processing. Furthermore, thes e results provide some evidence that there may be specialized mechanisms fo r processing different types of complex motion within the LP-pulvinar compl ex.