SUBCORTICAL MODULATION OF EARLY VISUAL-EVOKED RESPONSES DURING A RECOGNITION MEMORY TASK

The early components of visual evoked potentials are thought to reflec t the activity of the visual sensory pathways at a subcortical level. Animal studies have provided evidence that the anatomical connections and related physiological mechanisms allow cortical modulation of the activity of the subcortical visual pathways. The present experiments i nvestigated the modulation of early visual evoked potentials during a visual memory task in humans. The results revealed that three early co mponents (P45, P75 and N100) were modulated by some cognitive processe s related to memory. This memory-induced early modulation has been int erpreted as reflecting the influence of descending afferent connection s from the associative cortex to the subcortical visual relays. Such p rocesses may assist the early selection of visual information as a fun ction of the required task.