Event-related potentials (ERPs) in a learning and memory test

The present study outlines a new paradigm to investigate the effects of learning and memory on event-related potentials (ERPs). In the learning phase, subjects had to learn a sequence of 12 auditory consonant-vowel syllables. In the test phase, subjects had to detect and report a change in the learned sequence. Auditory ERPs were recorded from the frontal, vertex, and parietal midline positions. In the learning phase, an early negative effect (EN) and a P3 with a slow wave (SW) occurred for the learned syllables, whereas a pre-stimulus negativity (PSN) occurred prior to the syllables not yet learned. In the test phase, the PSN preceded both the replaced syllables and those presented in their old positions. The EN and an N2-P3 complex were elicited by the replaced syllables, the EN by the syllables presented in their old positions. It was concluded that the ERPs can display specific effects related to cognitive processes underlying learning and memory. The PSN was suggested to reflect the expectation of the stimuli, the EN the activation of a template and the rehearsal of the stimuli. The SW was suggested to be related to a template match process with the learned syllables. The N2, elicited by the replaced stimuli, could imply a cognitive template mismatch and the P3 with the SW the updating of working memory.