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

Ludersdorfer P, Schurz M, Richlan F, Kronbichler M, Wimmer H - Front Hum Neurosci (2013)

Bottom Line: 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.The positive auditory word-likeness effects may result from activation of orthographic information associated with the auditory words and pseudowords.

View Article: PubMed Central - PubMed

Affiliation: Centre for Neurocognitive Research and Department of Psychology, University of Salzburg Salzburg, Austria.

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.

No MeSH data available.


Related in: MedlinePlus

Conjunction analysis: overlap between the auditory words/pseudowords > artificial effect and the visual words < pseudowords (p < 0.001 voxel-wise threshold with a cluster extent threshold of p < 0.05, FWE corrected). The activation cluster is superimposed on the ventral surface of a standard brain template.
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Figure 3: Conjunction analysis: overlap between the auditory words/pseudowords > artificial effect and the visual words < pseudowords (p < 0.001 voxel-wise threshold with a cluster extent threshold of p < 0.05, FWE corrected). The activation cluster is superimposed on the ventral surface of a standard brain template.

Mentions: Next, we investigated the hypothesis that the found positive word-likeness effects for the auditory stimuli (i.e., words and pseudowords > artificial) reflect activation of visual orthographic information associated with the auditory words and pseudowords. Therefore, we tested whether the auditory effects coincide with the visual words < pseudowords effect. Since there was no activation difference between auditory words and pseudowords in the previous analyses, we collapsed the data and computed an auditory words/pseudowords > artificial contrast. The resulting activation cluster had a peak at MNI coordinates [−45 −58 −11] (t = 4.78; cluster extent = 105 voxels). A conjunction analysis (Friston et al., 2005; Nichols et al., 2005) showed a substantial overlap between the auditory words/pseudowords > artificial and the visual words < pseudowords cluster with a peak at [−45 −58 −11] (t = 4.53) and a cluster extent of 44 voxels (see Figure 3).


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

Ludersdorfer P, Schurz M, Richlan F, Kronbichler M, Wimmer H - Front Hum Neurosci (2013)

Conjunction analysis: overlap between the auditory words/pseudowords > artificial effect and the visual words < pseudowords (p < 0.001 voxel-wise threshold with a cluster extent threshold of p < 0.05, FWE corrected). The activation cluster is superimposed on the ventral surface of a standard brain template.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3756304&req=5

Figure 3: Conjunction analysis: overlap between the auditory words/pseudowords > artificial effect and the visual words < pseudowords (p < 0.001 voxel-wise threshold with a cluster extent threshold of p < 0.05, FWE corrected). The activation cluster is superimposed on the ventral surface of a standard brain template.
Mentions: Next, we investigated the hypothesis that the found positive word-likeness effects for the auditory stimuli (i.e., words and pseudowords > artificial) reflect activation of visual orthographic information associated with the auditory words and pseudowords. Therefore, we tested whether the auditory effects coincide with the visual words < pseudowords effect. Since there was no activation difference between auditory words and pseudowords in the previous analyses, we collapsed the data and computed an auditory words/pseudowords > artificial contrast. The resulting activation cluster had a peak at MNI coordinates [−45 −58 −11] (t = 4.78; cluster extent = 105 voxels). A conjunction analysis (Friston et al., 2005; Nichols et al., 2005) showed a substantial overlap between the auditory words/pseudowords > artificial and the visual words < pseudowords cluster with a peak at [−45 −58 −11] (t = 4.53) and a cluster extent of 44 voxels (see Figure 3).

Bottom Line: 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.The positive auditory word-likeness effects may result from activation of orthographic information associated with the auditory words and pseudowords.

View Article: PubMed Central - PubMed

Affiliation: Centre for Neurocognitive Research and Department of Psychology, University of Salzburg Salzburg, Austria.

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.

No MeSH data available.


Related in: MedlinePlus