Presentations

Abstract

Voices in the auditory modality, like faces in the visual modality, are the keys to person recognition. This fMRI experiment investigated the neural organisation of voice categories using a voice-training paradigm. Voice-morph continua were created between two female Hungarian speakers' voices saying six monosyllabic Hungarian words, one continuum per word. Listeners were trained to categorize the middle part of the continua as one voice. This trained voice category was associated with a face. Twenty-five listeners were tested twice with a one-week delay. To induce shifts in the trained category, listeners received feedback on their judgments such that the trained category was associated with different voice-morph intervals each week, allowing within-subject manipulation of whether stimuli corresponded to a trained voice-category centre, to a category boundary or to another voice. FMRI tests each week were preceded by eighty minutes training distributed over two consecutive days. The tests included implicit and explicit categorization tasks. Voice and face selective areas were defined in separate localizer runs. Group-averaged local maxima from these runs were used for small-volume correction analyses. During implicit categorization, stimuli corresponding to trained voice-category centres elicited lower activity than other stimuli in voice-selective regions of the right STS. During explicit categorization, stimuli corresponding to trained voice-category boundaries elicited higher activity than other stimuli in voice-selective regions of the right VLPFC. Furthermore, the unimodal presentation of voices that are more associated with a face may elicit higher activity in visual areas. These results map out the way voice categories are neurally represented.

Abstract

Syntactic priming has been frequently used to study syntactic processes in language production in monolinguals [1][2] and bilinguals [3]. In a previous study in language comprehension [4] we showed that passive sentences in English (the participant’s L2) can be primed by passive sentences in German (L1) and English (L2). This was manifested in faster reading times for target sentences and repetition suppression effects in left inferior frontal, left precentral and left middle temporal regions of interest in an fMRI study. However, syntactic priming in comprehension is complicated by the influence of verb repetition between prime and target [5][6]. Therefore, we conducted a reading time and fMRI study looking at the influence of verb repetition on syntactic priming. In this study of monolingual comprehension in Dutch we primed passive sentences as well as sentences with crossed-dependency structures. The reading time results revealed a syntactic priming effect for passive sentences, while the effect for crossed-dependency structure sentences interacted with the factor verb repetition. The preliminary fMRI results suggest that the repetition of passive structures leads to reductions in neural activity. The repetition of crossed dependency structures causes repetition enhancement, an increase in the BOLD response, an effect that interacts with the factor verb repetition. In conclusion, the influence of verb repetition on syntactic priming in comprehension is complex and seems to depend on the type of syntactic structure investigated. References [1] Bock K. (1986). Syntactic persistence in language production. Cognitive Psychology, 18(3), 355-387. [2] Pickering M, & Branigan H. (1999). Syntactic priming in language production. Trends in Cognitive Sciences, 3(4), 136-141. [3] Schoonbaert S, Hartsuiker RJ, & Pickering MJ. (2007). The representation of lexical and syntactic information in bilinguals: Evidence from syntactic priming. Journal of Memory and Language, 56(2), 153-171. [4] Weber K, & Indefrey P. (in press). Syntactic priming in German-English bilinguals during sentence comprehension. NeuroImage. [5] Arai M, van Gompel R, & Scheepers C. (2007). Priming ditransitive structures in comprehension. Cognitive Psychology, 54, 218-250. [6] Thothathiri M, & Snedeker J. (2008). Give and take: Syntactic priming during spoken language comprehension. Cognition, 108(1), 51-68.

Abstract

In an event-related fMRI study, we investigated to what extent semantic and
referential aspects of language comprehension recruit common or dis-
tinct neural ensembles. We compared BOLD responses to sentences containing semantically anomalous or coherent words, and to sentences containing referentially ambiguous pronouns (e.g., “Ronald told Frank that he...”), referentially failing pronouns (e.g., “Rose told Emily that he...”) or coherent pronouns. Semantic anomaly elicited activation increases in lateral prefrontal brain regions associated with semantic pro-
cessing. Referential failure elicited
activation increases in brain regions
associated with morphosyntactic processing, and additional activations
associated with elaborative inferenc
ing if readers took failing pronouns
to refer to unmentioned entities. Referential ambiguity selectively
recruited medial prefrontal regions,
suggesting that readers engaged in
problem-solving to select a unique
referent from the discourse model.
Furthermore, our results showed that semantic anomaly and referential
ambiguity recruit overlapping neural ensembles in opposite directions,
possibly reflecting the dynamic re
cruitment of semantic and episodic
processing to resolve semantically or referentially problematic situations.
These findings suggest that neurocogni
tive accounts of language compre-
hension will have to address not just how we parse a sentence and com-
bine individual word meanings, bu
t also how we determine who’s who
and what’s what during sentence and discourse comprehension