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L Shams

Publications and source records attributed to L Shams.

4 recordsLinked to original sources
PubMed2006

Sound alters activity in human V1 in association with illusory visual perception.

When a single brief visual flash is accompanied by two auditory bleeps, it is frequently perceived incorrectly as two flashes. Here, we used high field functional MRI in humans to examine the neural basis of this multisensory perceptual illusion. We show that activity in retinotopic visual cortex is increased by the presence of concurrent auditory stimulation, irrespective of any illusory perception. However, when concurrent auditory stimulation gave rise to illusory visual perception, activity in V1 was enhanced, despite auditory and visual stimulation being unchanged. These findings confirm that responses in human V1 can be altered by sound and show that they reflect subjective perception rather than the physically present visual stimulus. Moreover, as the right superior temporal sulcus and superior colliculus were also activated by illusory visual perception, together with V1, they provide a potential neural substrate for the generation of this multisensory illusion.

Acoustic Stimulation↗
PubMed2001

Sound alters visual evoked potentials in humans.

When a single flash is accompanied by two auditory beeps, the single flash is perceived as two flashes. We investigated whether this crossmodal influence on visual perception occurs at the level of the modality-specific visual pathway or later. We compared the visual evoked potentials (VEPs) in the presence and absence of sound. Activity was modulated extensively and with short latency in trials in which an illusory flash was perceived. In addition, the brain potentials for the illusory flash were qualitatively very similar to those for a physical flash, suggesting that the same mechanism underlies the percept of both illusory and physical flashes. These results suggest that the activity in the visual cortex can be modulated by sound. This implication challenges the general belief that the visual cortical processing is independent of other modalities.

Acoustic Stimulation↗
PubMed2001

Sensory modalities are not separate modalities: plasticity and interactions.

Historically, perception has been viewed as a modular function, with the different sensory modalities operating independently of each other. Recent behavioral and brain imaging studies challenge this view, by suggesting that cross-modal interactions are the rule and not the exception in perception, and that the cortical pathways previously thought to be sensory-specific are modulated by signals from other modalities.

Animals↗