ERP effects of meaningful and non-meaningful sound processing in anterior temporal patients

The contribution of the anterior temporal lobe to the processing of environmental sounds was investigated in patients with primary lesions in the anterior portion of the left (ATL) and right (ATR) temporal lobe in comparison to healthy controls. Two controversial questions were addressed: (1) whether environmental sounds are processed similarly for meaning as language, and (2) whether task-dependent lateralized semantic and perceptual effects observed in earlier studies persist when testing environmental sounds independent of task.

In an event-related brain potential (ERP) experiment we examined the effect of meaningful and non-meaningful novel sound processing in a novelty oddball paradigm.

Healthy controls and both patient groups displayed a normal target P3b as well as a novelty P3a. In addition, while healthy controls differentiated non-meaningful and meaningful novel sounds in the novelty P3a at posterior lateral and midline electrode-sites, all patients showed this effect only at midline sites. Lastly, the P3a effect was followed by a larger N400 amplitude rise for meaningful compared to non-meaningful novel sounds in healthy controls, but not in either patient group.

The present data indicate that independent of task both the left and right anterior temporal lobe is crucial for lexical-semantic processing of novel sounds.