Cortical potentials in humans reflecting the direction of object motion.

In the monkey, cortical areas can be localized which are specific for the processing of form, colour, or motion, and it is expected that the human visual cortex is organized in a similar way. The recording of scalp potentials generated by neural activity of underlying cortical areas is a non-invasive method which can be used to study the functional organization of the visual cortex with a high temporal resolution. In the present study we recorded slow cortical potentials from normal subjects to investigate how motion stimuli of variable complexity are processed in human visual cortex. The results show that the pattern of cortical activation is dependent on the type of stimulus. When random dots were moving within the entire stimulus field, or during counterphase flicker, maximal activation occurred over occipital electrode sites. During object motion a pronounced activation is recorded at parietal locations, with the direction of object motion being reflected by the time course of this activation.