Impaired acquisition of new words after left temporal lobectomy despite normal fast-mapping behavior

Abstract

Word learning under different conditions has been proposed to rely on different 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 learning formats. Previous research has shown that word learning in contrastive fast mapping conditions may rely on different neural substrates than explicit encoding conditions (Sharon, Moscovitch, & Gilboa, 2011). In the current investigation, we used a previously reported word learning task that implemented two distinct study formats (Warren & 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.

Small Sets of Novel Words Are Fully Retained After 1-Week in Typically Developing Children and Down Syndrome: A Fast Mapping Study

“…Inconsistent with findings from Sharon et al (2011) and contrary to our hypothesis, our results showed no significant benefit in the FM condition for the DS group. This result is consistent with other recent work failing to measure a FM benefit in healthy older adults, memory-impaired patients (damage to the hippocampus), patients with amnesia (damage to the hippocampus), and patients with left temporal lobectomies (Greve et al, 2014; Smith et al., 2014; Warren & Duff, 2014; Warren et al, 2016). Therefore, given these recent findings, there is mixed evidence regarding the benefit of FM for the retention of arbitrary labels in individuals that do not have amnesia.…”

“…Much work has been conducted regarding the role of sleep in this process (Diekelmann & Born, 2010). However, a few studies investigating a learning mechanism called fast mapping (FM), have provided some evidence suggesting that the rapid acquisition of novel arbitrary associations can be achieved independently of the hippocampus when words are learned under certain conditions (Sharon, Moscovitch, & Gilboa, 2011, but also see Greve, Cooper, & Henson, 2014; Smith, Urgolites, Hopkins, & Squire, 2014; Warren & Duff, 2014; Warren, Tranel, & Duff, 2016). …”

Cross-Situational Statistical Learning of New Words Despite Bilateral Hippocampal Damage and Severe Amnesia

“…We speculate that non-hippocampal brain regions or structures that contribute to statistical learning may include medial temporal lobe neocortex (McClelland et al, 1995;Norman and O'Reilly, 2003) and basal ganglia (Poldrack et al, 2001;Poldrack and Packard, 2003;Poldrack and Rodriguez, 2004) among others (Bischoff-Grethe et al, 2000;McNealy et al, 2006;Turk-Browne et al, 2009;Karuza et al, 2013). CSSL may also benefit more specifically from contributions by a network of language-related brain regions including anterior and lateral temporal lobes (McNealy et al, 2006;Davis et al, 2009;Karuza et al, 2013;Warren et al, 2016). Additional functional neuroimaging and neuropsychological investigations might address this hypothesis.…”

High feature overlap reveals the importance of anterior and medial temporal lobe structures for learning by means of fast mapping

“…The role of anterior and medial temporal lobe structures in learning by means of fast mapping 4 Despite evidence that FM can enable direct integration of arbitrary associations, other studies revealed contradictory findings (cf. Cooper, Greve, & Henson, 2019;Greve, Cooper, & Henson, 2014;Smith, Urgolites, Hopkins, & Squire, 2014;Warren & Duff, 2014;Warren, Tranel, & Duff, 2016). However, the experimental designs and procedures of some of these studies deviated from the original paradigm, such that learning was intentional (e.g., Warren & Duff, 2014) or the associations had been repeatedly recalled before the recognition memory test (e.g., Warren & Duff, 2014;Warren et al, 2016).…”

“…Cooper, Greve, & Henson, 2019;Greve, Cooper, & Henson, 2014;Smith, Urgolites, Hopkins, & Squire, 2014;Warren & Duff, 2014;Warren, Tranel, & Duff, 2016). However, the experimental designs and procedures of some of these studies deviated from the original paradigm, such that learning was intentional (e.g., Warren & Duff, 2014) or the associations had been repeatedly recalled before the recognition memory test (e.g., Warren & Duff, 2014;Warren et al, 2016). Moreover, rapid cortical integration through FM was not always investigated in patients with lesions confined to the hippocampus but also in patients with extended lesions to extra-hippocampal structures or with complete left-temporal lobectomies (Warren et al, 2016).…”