MOTION INTEGRATION IN A THALAMIC VISUAL NUCLEUS

Thalamic nuclei have long been regarded as passive relay stations for sensory information en route to higher level processing in the cerebra l cortex. Recently, physiological and theoretical studies have reasses sed the role of the thalamus and it has been proposed that thalamic nu clei may actively participate with cortical areas in processing specif ic information(1-4). In support of this idea, we now show that a subse t of neurons in an extrageniculate visual nucleus, the lateral-posteri or pulvinar complex, can signal the true direction of motion of a plai d pattern, indicating that thalamic cells can integrate different moti on signals into a coherent moving percept(5-8). This is the first time that these computations have been found to occur outside the higher-o rder cortical areas(5,6,9,10). Our fi(n)dings implicate extrageniculat e cortico-thalamo-cortical loops in the dynamic processing of image mo tion, and, more generally, as basic computational modules involved in analysing specific features of complex visual scenes.