EEG — Lambda Waves (Positive Occipital Sharp Transients with Visual Saccades in Awake Adults)

A 28-year-old patient undergoes routine EEG during a neurological evaluation. The recording shows sharp, surface-positive transients of 100–150 microvolts amplitude and <200 ms duration recorded maximally over the occipital electrodes (O1, O2, Oz). These waveforms appear in clusters while the patient visually scans a complex pattern on a screen. The concurrent EOG channel shows that each transient follows the end of a saccadic eye movement by approximately 50–100 ms. The waveforms disappear immediately when the patient closes their eyes or looks at a blank wall. The structure marked **A** in the diagram represents these normal EEG findings. Which of the following best describes the pathophysiological basis of the waveforms marked **A**?