title: Impaired acquisition of new words after left temporal lobectomy despite normal fast-mapping behavior.
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.
authors.affiliation: Department of Neurology, Carver College of Medicine, University of Iowa, 2155-H RCP, 200 Hawkins Drive, Iowa City, IA 52242, USA. Electronic address: david-e-warren@uiowa.edu.
authors.forename: David E
authors.initials: DE
authors.lastname: Warren
authors.affiliation: Department of Neurology, Carver College of Medicine, University of Iowa, 2155-H RCP, 200 Hawkins Drive, Iowa City, IA 52242, USA; Department of Psychology, College of Liberal Arts and Sciences, University of Iowa, 121 SHC, 250 Hawkins Drive, Iowa City, IA 52242, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Tranel
authors.affiliation: Department of Neurology, Carver College of Medicine, University of Iowa, 2155-H RCP, 200 Hawkins Drive, Iowa City, IA 52242, USA; Department of Communication Sciences and Disorders, College of Liberal Arts and Sciences, University of Iowa, 121 SHC, 250 Hawkins Drive, Iowa City, IA 52242, USA.
authors.forename: Melissa C
authors.initials: MC
authors.lastname: Duff
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001931:Brain Mapping; D003463:Cues; D004827:Epilepsy / Q000601:surgery; D005133:Eye Movements; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D020232:Kluver-Bucy Syndrome / Q000150:complications*; D008297:Male; D008569:Memory Disorders / Q000209:etiology*; D011939:Mental Recall / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D021641:Recognition, Psychology / Q000502:physiology; D012660:Semantics; D014706:Verbal Learning / Q000502:physiology*
keywords: Hippocampus; Language; Left temporal lobe; Memory; Unilateral temporal lobectomy; Word learning