Impaired acquisition of new words after left temporal lobectomy despite normal fast-mapping behavior. (8th January 2016)

• Record Type: Journal Article
• Authors: Warren, David E.; Tranel, Daniel; Duff, Melissa C.
• Is Part Of: Neuropsychologia. Volume 80(2016)
• Page Start: 165
• Page End: 175
• Publication Date: 2016-01-08
• Subjects: Memory -- Language -- Word learning -- Hippocampus -- Unilateral temporal lobectomy -- Left temporal lobe; Neuropsychology -- Periodicals; Neurology -- Periodicals; Psychophysiology -- Periodicals; Neuropsychologie -- Périodiques; Neuropsychology; Periodicals; Electronic journals; 616.8
• DOI: 10.1016/j.neuropsychologia.2015.11.016
• Languages: English
• ISSNs: 0028-3932

Abstract

Abstract: Word learning has been proposed to rely on unique brain regions including the temporal lobes, and the left temporal lobe appears to be especially important. In order to investigate the role of the left temporal lobe in word learning under different conditions, we tested whether patients with left temporal lobectomies ( N =6) could learn novel words using two distinct formats. Previous research has shown that word learning in contrastive fast mapping conditions may rely on different neural substrates than explicit encoding conditions (Sharon et al., 2011 ). In the current investigation, we used a previously reported word learning task that implemented two distinct study formats (Warren and Duff, 2014 ): a contrastive fast mapping condition in which a picture of a novel item was displayed beside a picture of a familiar item while the novel item's name was presented aurally ("Click on the numbat."); and an explicit encoding (i.e., control) condition in which a picture of a novel item was displayed while its name was presented aurally ("This is a numbat."). After a delay, learning of the novel words was evaluated with memory tests including three-alternative forced-choice recognition, free recall, cued recall, and familiarity ratings. During the fast-mapping study condition both the left temporal lobectomy and healthy comparison groups performed well, but at test only the comparison group showed evidence of novel word learning. Our findings indicate that unilateral resection of the left temporal lobe including the hippocampus and temporal pole can severely impair word learning, and that fast-mapping study conditions do not promote subsequent word learning in temporal lobectomy populations. Highlights: The neural substrates of word learning may be located within the brain's left hemisphere. Word learning by left temporal lobectomy (TL) patients was tested in 2 conditions. TL patients did not learn words in explicit encoding or fast-mapping conditions. TL produced a word-learning deficit as severe as bilateral hippocampal damage. Structures of the left temporal lobe are necessary for normal word learning.