Visual evoked spread spectrum analysis (VESPA) responses to stimuli biased towards magnocellular and parvocellular pathways

Stimulus contrast fluctuations were controlled while the properties of a novel ERP known as the VESPA (Visual Evoked Spread Spectrum Analysis) were examined using data from 8 healthy human subjects. Substantial differences were seen between the morphologies of VESPAs obtained using low contrast stimuli when compared with those obtained using high contrast and full contrast range stimuli. Topographic distributions for both responses are compared and the findings are considered in terms of the response characteristics of the magnocellular and parvocellular visual pathways and the VESPA method itself.