Different effects of lesions to auditory core and belt cortex on auditory recognition in dogs

Auditory recognition memory, in contrast to memory in other modalities, is not affected by damage to the perihinal cortex, and its neural basis remains unknown. In an attempt to elucidate this problem, we investigated the role of canine auditory core and belt areas in auditory recognition. Either core or posterior belt areas were surgically removed. The core and belt regions were defined on the basis of response properties and thalamocortical connectivity established in previous studies. The animals were tested on auditory delayed matching to sample (DMS, a recognition memory task) using complex, trial-unique auditory stimuli. Both core and belt lesions impaired auditory recognition, however, the underlying deficit was different. Lesions to the core areas impaired auditory localization abilities. Lesions to the posterior belt areas did not affect this component of the recognition task, but affected auditory quality discrimination and/or recognition. The deficit following the posterior belt lesion did not increase with retention delay, suggesting that auditory belt areas do not constitute a substrate for auditory recognition memory. Their main function appears to be processing of complex sound patterns, including immediate recognition.