The human medial-temporal lobe (MTL) plays a crucial role in memory processing, both in encoding of novel events and retrieving past experiences. We recorded event-related potentials (ERP) during continuous recognition tasks to investigate the underlying neural mechanisms and timing of memory encoding and recognition in healthy subjects and patients with memory impairments. In the first study we showed that patients with MTL lesions lack the early frontal evoked potential upon immediate picture repetition, normally observed in healthy subjects. In the second study we investigated the temporal distribution of MTL-mediated processes in healthy subjects. Encoding-related ERP modulations occurred at 145-205 ms and preceded recognition (405-470 ms). The third study showed disrupted novelty detection and encoding in patients with Alzheimer's disease, as reflected in lack of activity in the MTL required for discrimination and encoding of novel stimuli. This thesis broadens the understanding of MTL role in memory functioning.