Dataset Information

Opposite effects of visual and auditory word-likeness on activity in the visual word form area.

ABSTRACT: The present fMRI study investigated the effects of word-likeness of visual and auditory stimuli on activity along the ventral visual stream. In the context of a one-back task, we presented visual and auditory words, pseudowords, and artificial stimuli (i.e., false-fonts and reversed-speech, respectively). Main findings were regionally specific effects of word-likeness on activation in a left ventral occipitotemporal region corresponding to the classic localization of the Visual Word Form Area (VWFA). Specifically, we found an inverse word-likeness effect for the visual stimuli in the form of decreased activation for words compared to pseudowords which, in turn, elicited decreased activation compared to the artificial stimuli. For the auditory stimuli, we found positive word-likeness effects as both words and pseudowords elicited more activation than the artificial stimuli. This resulted from a marked deactivation in response to the artificial stimuli and no such deactivation for words and pseudowords. We suggest that the opposite effects of visual and auditory word-likeness on VWFA activation can be explained by assuming the involvement of visual orthographic memory representations. For the visual stimuli, these representations reduce the coding effort as a function of word-likeness. This results in highest activation to the artificial stimuli and least activation to words for which corresponding representations exist. The positive auditory word-likeness effects may result from activation of orthographic information associated with the auditory words and pseudowords. The view that the VWFA has a primarily visual function is supported by our findings of high activation to the visual artificial stimuli (which have no phonological or semantic associations) and deactivation to the auditory artificial stimuli. According to the phenomenon of cross-modal sensory suppression such deactivations during demanding auditory processing are expected in visual regions.

SUBMITTER: Ludersdorfer P

PROVIDER: S-EPMC3756304 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Opposite effects of visual and auditory word-likeness on activity in the visual word form area.

Ludersdorfer Philipp P Schurz Matthias M Richlan Fabio F Kronbichler Martin M Wimmer Heinz H

Frontiers in human neuroscience 20130829

The present fMRI study investigated the effects of word-likeness of visual and auditory stimuli on activity along the ventral visual stream. In the context of a one-back task, we presented visual and auditory words, pseudowords, and artificial stimuli (i.e., false-fonts and reversed-speech, respectively). Main findings were regionally specific effects of word-likeness on activation in a left ventral occipitotemporal region corresponding to the classic localization of the Visual Word Form Area (V ...[more]

PMID: 24009569

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Project description:The visual word form area (VWFA) is a region in the left occipitotemporal sulcus of literate individuals that is purportedly specialized for visual word recognition. However, there is considerable controversy about its functional specificity and connectivity, with some arguing that it serves as a domain-general, rather than word-specific, visual processor. The VWFA is a critical region for testing hypotheses about the nature of cortical organization, because it is known to develop only through experience (i.e., reading acquisition), and widespread literacy is too recent to have influenced genetic determinants of brain organization. Using a combination of advanced fMRI analysis techniques, including individual functional localization, multivoxel pattern analysis, and high-resolution resting-state functional connectivity (RSFC) analyses, with data from 33 healthy adult human participants, we demonstrate that (1) the VWFA can discriminate words from nonword letter strings (pseudowords); (2) the VWFA has preferential RSFC with Wernicke's area and other core regions of the language system; and (3) the strength of the RSFC between the VWFA and Wernicke's area predicts performance on a semantic classification task with words but not other categories of visual stimuli. Our results are consistent with the hypothesis that the VWFA is specialized for lexical processing of real words because of its functional connectivity with Wernicke's area.SIGNIFICANCE STATEMENT The visual word form area (VWFA) is critical for determining the nature of category-related organization of the ventral visual system. However, its functional specificity and connectivity are fiercely debated. Recent work concluded that the VWFA is a domain-general, rather than word-specific, visual processor with no preferential functional connectivity with the language system. Using more advanced techniques, our results stand in stark contrast to these earlier findings. We demonstrate that the VWFA is highly specialized for lexical processing of real words, and that a fundamental factor driving this specialization is its preferential intrinsic functional connectivity with core regions of the language system. Our results support the hypothesis that intrinsic functional connectivity contributes to category-related specialization within the human ventral visual system.

Dataset Information

Opposite effects of visual and auditory word-likeness on activity in the visual word form area.

Publications

Opposite effects of visual and auditory word-likeness on activity in the visual word form area.

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