Context-dependent interpretation of words: Evidence for interactive neural processes

Abstract

The meaning of a word usually depends on the context in which it occurs. This study investigated the neural mechanisms involved in computing word meanings that change as a function of syntactic context. Current semantic processing theories suggest that word meanings are retrieved from diverse cortical regions storing sensory-motor and other types of semantic information, and are further integrated with context in left inferior frontal gyrus (LIFG). Our fMRI data indicate that brain activity in an area sensitive to motion and action semantics -the posterior middle temporal gyrus (PMTG) -is modulated by a word's syntactic context. Ambiguous words such as bowl were presented in minimal disambiguating contexts indicating object (the bowl) or action (to bowl) meanings, and were compared to low-ambiguity controls. Ambiguous words elicited more activity than low-ambiguity controls in LIFG and various meaning-related areas such as PMTG. Critically, ambiguous words also elicited more activity in to-contexts than the-contexts in PMTG and LIFG, suggesting that contextual integration strengthened the action meaning in both areas. The pattern of results suggests that the activation of lexical information in PMTG was sensitive to contextual disambiguating information and that processing context-dependent meanings may involve interactions between frontal and posterior areas.

Going beyond Inferior Prefrontal Involvement in Semantic Control: Evidence for the Additional Contribution of Dorsal Angular Gyrus and Posterior Middle Temporal Cortex

“…In these studies, it has been shown that the specificity of the judgment (decisions based on global semantic vs. feature-specific similarity) as well as the strength of the semantic association between probe and target (relative to probe and distracter) modulate left ventral pFC activation (Badre, Poldrack, Pare-Blagoev, Insler, & Wagner, 2005;Wagner, Pare-Blagoev, Clark, & Poldrack, 2001;Thompson-Schill, DʼEsposito, Aguirre, & Farah, 1997)-that is, a weaker association between probe and target requires a greater degree of on-line exploration of the semantic database. In addition, a number of studies that look at the processing of semantically ambiguous materials-for example, metaphors and homonymshave shown that stimuli that are inherently multifaceted (in terms of their relationship to underlying meaning) also give rise to greater processing demands with the executive semantic system (Hoenig & Scheef, 2009;Mashal, Faust, Hendler, & Jung-Beeman, 2009;Chen, Widick, & Chatterjee, 2008;Gennari, MacDonald, Postle, & Seidenberg, 2007;Shibata, Abe, Terao, & Miyamoto, 2007;Stringaris, Medford, Giampietro, Brammer, & David, 2007;Zempleni, Renken, Hoeks, Hoogduin, & Stowe, 2007;Lee & Dapretto, 2006;Rodd, Davis, & Johnsrude, 2005;Rapp, Leube, Erb, Grodd, & Kircher, 2004). These findings are unsurprising given that left ventral pFC has been implicated in a wide range of different executive processes, including task switching, resolution of proactive interference and strategic priming (Gold et al, 2006;Brass, Derrfuss, Forstmann, & Cramon, 2005).…”

Differential age effects on lexical ambiguity resolution mechanisms

“…This interpretation is bolstered by the fact that the temporal lobe, shown to be an important part of the N400's distributed neural source (Elger et al, 1997;Halgren, Baudena, Heit, Clarke, Marinkovic, Chauvel et al, 1994;McCarthy, Nobre, Bentin, & Spencer, 1995;Nobre & McCarthy, 1994;Van Petten & Luka, 2006), has been viewed as the storage site for long-term semantic knowledge accessed during the bottom-up processing of meaningful stimuli (Badre, Poldrack, PareBlagoev, Insler, & Wagner, 2005;Thompson-Schill, D'Esposito, & Kan, 1999). Enhanced temporal lobe activation has also been found to lexically ambiguous stimuli in some imaging studies, and has been interpreted as reflecting lexico-semantic processing or semantic integration (Gennari, MacDonald, Postle, & Seidenberg, 2007;Rodd, Davis, & Johnsrude, 2005) or consequences of semantic mismatch (Zempleni, Renken, Hoeks, Hoogduin, & Stowe, 2007).…”

“…However, our prior work (Lee & Federmeier, 2009), buttressed by neuroimaging findings (Gennari, MacDonald, Postle, & Seidenberg, 2007;Ihara, Hayakawa, Wei, Munetsuna, & Fujimaki, 2007;Rodd, Davis, & Johnsrude, 2005;Zempleni, Renken, Hoeks, Hoogduin, & Stowe, 2007), indicates that multiple neural mechanisms are involved in ambiguity resolution, and that the nature of the information provided by different types of context is important for determining when and how these mechanisms are recruited. The current study was designed to examine whether normal aging imposes differential effects on these subsystems, and, more specifically, to test the hypothesis that the more controlled, topdown, frontal mechanisms important for resolving ambiguity under difficult selection conditions would be more affected by advancing age than the mechanisms used to resolve ambiguity in the presence of biasing semantic supports.…”

Things to think with: words and objects as material symbols

“…The problem is that the meaning of any particular word is highly confined and constrained by the context of the other words (Gennari et al 2007).…”