Prefrontal and posterior cortical activation during auditory working memory

The present study investigated brain mechanisms underlying auditory memory. In a modified Stemberg memory scanning task, 11 subjects indicated whether a probe sound was part of a previously presented 4-item memory set by a button press. Behaviorally, subjects responded fastest and most accurately to probes that matched the last memory set items and slowest and least accurately to negative probes and to positive probes to the first two memory set items. Electrophysiologically, probes to the last memory set items' elicited the largest amplitude and earliest latency P3 components while other probes elicited smaller amplitude, prolonged P3s as well as a negativity around 400 ms. These results suggest that subjects utilized a trace strength/self-terminating search model to perform the memory scanning task. Subjects only generated the P3 component during the matching phase of the auditory memory task while a sustained frontal negativity was elicited during both the encoding and matching phase. Taken together these findings provide evidence of differential activation of distributed neural activity during non-linguistic auditory memory.