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A neural network model can explain ventriloquism aftereffect and its generalization across sound frequencies.

Magosso E, Cona F, Ursino M - Biomed Res Int (2013)

Bottom Line: Exposure to synchronous but spatially disparate auditory and visual stimuli produces a perceptual shift of sound location towards the visual stimulus (ventriloquism effect).The model provides a coherent theoretical framework to explain the apparently contradictory results found in the literature.Model mechanisms and hypotheses are discussed in relation to neurophysiological and psychophysical data.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi", University of Bologna, Via Venezia 52, 47521 Cesena, Italy.

ABSTRACT
Exposure to synchronous but spatially disparate auditory and visual stimuli produces a perceptual shift of sound location towards the visual stimulus (ventriloquism effect). After adaptation to a ventriloquism situation, enduring sound shift is observed in the absence of the visual stimulus (ventriloquism aftereffect). Experimental studies report opposing results as to aftereffect generalization across sound frequencies varying from aftereffect being confined to the frequency used during adaptation to aftereffect generalizing across some octaves. Here, we present an extension of a model of visual-auditory interaction we previously developed. The new model is able to simulate the ventriloquism effect and, via Hebbian learning rules, the ventriloquism aftereffect and can be used to investigate aftereffect generalization across frequencies. The model includes auditory neurons coding both for the spatial and spectral features of the auditory stimuli and mimicking properties of biological auditory neurons. The model suggests that different extent of aftereffect generalization across frequencies can be obtained by changing the intensity of the auditory stimulus that induces different amounts of activation in the auditory layer. The model provides a coherent theoretical framework to explain the apparently contradictory results found in the literature. Model mechanisms and hypotheses are discussed in relation to neurophysiological and psychophysical data.

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Effects of network training with E0aadapt = 17 and of network testing (after adaptation) with E0atest = 17. The adaptation position was 80° and the adaptation frequency was 1.1 kHz. The panels show the same quantities as respective panels in Figure 8.
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fig9: Effects of network training with E0aadapt = 17 and of network testing (after adaptation) with E0atest = 17. The adaptation position was 80° and the adaptation frequency was 1.1 kHz. The panels show the same quantities as respective panels in Figure 8.

Mentions: Figure 8 shows the results of the network training with E0aadapt = 20 and network testing with E0atest = 20; Figure 9 displays the results of the network training with E0aadapt = 17 and network testing with E0atest = 17. In both figures, the first two columns represent the synapses before adaptation (first column) and after adaptation (second column) targeting five different auditory neurons, all located at 100° (the position of the visual stimulus during adaptation) and at five different frequencies (1.1 kHz, 2.2 kHz, 4.4 kHz, 8.8 kHz, and 11.6 kHz). The third column displays the response of the trained network to the test stimulus applied at the adaptation position (80°) and at the five different frequencies.


A neural network model can explain ventriloquism aftereffect and its generalization across sound frequencies.

Magosso E, Cona F, Ursino M - Biomed Res Int (2013)

Effects of network training with E0aadapt = 17 and of network testing (after adaptation) with E0atest = 17. The adaptation position was 80° and the adaptation frequency was 1.1 kHz. The panels show the same quantities as respective panels in Figure 8.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3818813&req=5

fig9: Effects of network training with E0aadapt = 17 and of network testing (after adaptation) with E0atest = 17. The adaptation position was 80° and the adaptation frequency was 1.1 kHz. The panels show the same quantities as respective panels in Figure 8.
Mentions: Figure 8 shows the results of the network training with E0aadapt = 20 and network testing with E0atest = 20; Figure 9 displays the results of the network training with E0aadapt = 17 and network testing with E0atest = 17. In both figures, the first two columns represent the synapses before adaptation (first column) and after adaptation (second column) targeting five different auditory neurons, all located at 100° (the position of the visual stimulus during adaptation) and at five different frequencies (1.1 kHz, 2.2 kHz, 4.4 kHz, 8.8 kHz, and 11.6 kHz). The third column displays the response of the trained network to the test stimulus applied at the adaptation position (80°) and at the five different frequencies.

Bottom Line: Exposure to synchronous but spatially disparate auditory and visual stimuli produces a perceptual shift of sound location towards the visual stimulus (ventriloquism effect).The model provides a coherent theoretical framework to explain the apparently contradictory results found in the literature.Model mechanisms and hypotheses are discussed in relation to neurophysiological and psychophysical data.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical, Electronic, and Information Engineering "Guglielmo Marconi", University of Bologna, Via Venezia 52, 47521 Cesena, Italy.

ABSTRACT
Exposure to synchronous but spatially disparate auditory and visual stimuli produces a perceptual shift of sound location towards the visual stimulus (ventriloquism effect). After adaptation to a ventriloquism situation, enduring sound shift is observed in the absence of the visual stimulus (ventriloquism aftereffect). Experimental studies report opposing results as to aftereffect generalization across sound frequencies varying from aftereffect being confined to the frequency used during adaptation to aftereffect generalizing across some octaves. Here, we present an extension of a model of visual-auditory interaction we previously developed. The new model is able to simulate the ventriloquism effect and, via Hebbian learning rules, the ventriloquism aftereffect and can be used to investigate aftereffect generalization across frequencies. The model includes auditory neurons coding both for the spatial and spectral features of the auditory stimuli and mimicking properties of biological auditory neurons. The model suggests that different extent of aftereffect generalization across frequencies can be obtained by changing the intensity of the auditory stimulus that induces different amounts of activation in the auditory layer. The model provides a coherent theoretical framework to explain the apparently contradictory results found in the literature. Model mechanisms and hypotheses are discussed in relation to neurophysiological and psychophysical data.

Show MeSH
Related in: MedlinePlus