Neural correlates of partial lexical activation

Abstract

As a spoken word unfolds over time, it is temporarily consistent with the acoustic forms of multiple words. Previous behavioral research has shown that, in the face of temporary ambiguity about how a word will end, multiple candidate words are briefly activated. Here, we provide neural imaging evidence that lexical candidates only temporarily consistent with the input activate perceptually based semantic representations. An artificial lexicon and novel visual environment were used to target human MT/V5 and an area anterior to it which have been shown to be recruited during the reading of motion words. Participants learned words that referred to novel objects and to motion or color/texture changes that the objects underwent. The lexical items corresponding to the change events were organized into phonologically similar pairs differing only in the final syllable. Upon hearing spoken scene descriptions in a posttraining verification task, participants showed greater activation in the left hemisphere anterior extent of MT/V5 when motion words were heard than when nonmotion words were heard. Importantly, when a nonmotion word was heard, the level of activation in the anterior extent of MT/V5 was modulated by whether there was a phonologically related competitor that was a motion word rather than another nonmotion word. These results provide evidence of activation of a perceptual brain region in response to the semantics of a word while lexical competition is in process and before the word is fully recognized.fMRI ͉ MT/V5 ͉ semantic representations ͉ spoken word recognition S poken words unfold over time as a series of rapidly changing acoustic events. To comprehend spoken language, the listener must map this speech signal onto representations of meaning. Behavioral (1-3) and neuroimaging (4) evidence suggests that multiple words that are temporarily consistent with the unfolding acoustic input compete for recognition. Although experiments using a variety of behavioral paradigms have shown that syntactic, semantic, and nonlinguistic features of the words in the active competitor set are available before word recognition is complete (5-9), there is no neural evidence indicating whether semantic representations are involved in this competition. However, other behavioral tasks have shown interactions between perceptual processing and language processing (10-13), and recent neuroimaging evidence suggests that the concepts that are activated by written or spoken words are distributed across cortical regions intrinsically involved in perception and action (7,(14)(15)(16)(17)(18)(19)(20)(21)(22). Nevertheless, there is debate about whether the recruitment of these semantically induced activations in perceptual brain areas is automatic or strategic (23). In this article, we demonstrate that even lexical candidates that are only temporarily consistent with the unfolding word activate brain regions involved in perceptual processing, thus providing clear evidence that lexical processing automatically activates perceptually based...

Arguments about the nature of concepts: Symbols, embodiment, and beyond

“…Similar phenomena have been observed in the context of visual motion processing (e.g., Pirog et al, 2008; Dils and Boroditsky, 2010; but see Pavan and Baggio, 2010), color processing (e.g., Simmons et al, 2007), visual form processing (e.g. Zwaan et al, 2002; but see Rommers, Meyer, and Huettig 2013), gustatory processing (Simmons et al, 2013), and auditory processing (Kiefer et al, 2008)—and similar considerations apply as to whether the phenomena reflect the format of conceptual representations or rather the processing dynamics that obtain between amodal symbolic representations and input/output systems.…”

Behavioral patterns and lesion sites associated with impaired processing of lexical and conceptual knowledge of actions

“…A number of fMRI studies have reported significant engagement of this region during the processing of action verbs and sentences, compared to various baseline conditions (verbs: Damasio et al, 2001; Grossman et al, 2002; Kable et al, 2002, 2005; Noppeney et al, 2005; Tranel et al, 2005; Bedny et al, 2008; Kemmerer et al, 2008; Pirog Revill et al, 2008; Pulvermüller et al, 2009; sentences: Tettamanti et al, 2005; Wallentin et al, 2005; Chen et al, 2008; Tyler et al, 2008; Deen & McCarthy, 2010; Saygin et al, in press). These findings are often interpreted as evidence that the left pMTG—together with the left posterior superior temporal sulcus (pSTS), which was also included in our lesion maps—subserves the visual manner-of-motion features of action concepts.…”

The Two-Level Theory of verb meaning: An approach to integrating the semantics of action with the mirror neuron system

“…Finally, semantic conditions involving automatic processing might draw upon paradigms like lexical decision (e.g., “Is trudge a real word of English?”) and masked repetition priming (i.e., a technique that probes semantic access in a way that is completely subliminal yet also detectable with both fMRI and ERPs; see Naccache & Dehaene [2001]). For other novel approaches to distinguishing between automatic semantic processing and strategic imagery generation, see Hauk et al (2008a) and Pirog Revill et al (2008).…”

“…While investigating possible relations between mirror neurons and verb meanings in the left parietal cortex is beyond the purview of this paper, it is clearly an important direction for future research (e.g., see Glenberg & Gallese, submitted, for a new theoretical proposal about the role of action-related frontoparietal circuits in sentence processing). In addition, our hypotheses do not encompass the posterolateral temporal cortex, despite the fact that this region plays a major role, albeit predominantly in the right hemisphere, in biological motion perception (for a review see Blake & Shiffrar, 2007) and has also been implicated, albeit predominantly in the left hemisphere, in the semantic processing of action verbs (e.g., Kable et al, 2002, 2005; Noppeney et al, 2005; Kemmerer et al, 2008; Tranel et al, 2008; Pirog Revill et al, 2008; see also relevant data on thematic roles and event structure provided by, e.g., Wu et al, 2007; Grewe et al, 2007; Bedny et al, in press). We would like to emphasize, however, that even though we do not discuss the posterolateral temporal cortex in detail, we nevertheless refer, at several points in our presentation, to findings about this region that are especially pertinent to our arguments (see in particular sections 3.2.2.1 and 4.2.2.2).…”