Recognition memory for text and melody of songs after unilateral temporal lobe lesion: evidence for dual encoding.

The role of left and right temporal lobes in memory for songs (words sung to a tune) was investigated. Patients who had undergone focal cerebral excision for the relief of intractable epilepsy along with normal control subjects were tested in 2 recognition memory tasks. The goal of Experiment 1 was to examine recognition of words and of tunes when they were presented together in an unfamiliar song. In Experiment 2, memory for spoken words and tunes sung without words was independently tested in 2 separate recognition tasks. The results clearly showed (a) a deficit after left temporal lobectomy in recognition of text whether sung to a tune or spoken without musical accompaniment, (b) impaired melody recognition when the tune was sung with new words following left or right temporal lobectomy and (c) impaired melody recognition in the absence of lyrics following right but not left temporal lobectomy. The different role of each temporal lobe in memorizing songs provides evidence for the use of dual memory codes. The verbal code is consistently related to left temporal lobe structures, whereas the melodie code my depend on either or both temporal lobe mechanisms, according to the type of encoding involved.