de.mpg.escidoc.pubman.appbase.FacesBean
English
 
Help Guide Disclaimer Contact us Login
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Multisensory integration for orienting responses in humans requires the activation of the superior colliculus

MPS-Authors
http://pubman.mpdl.mpg.de/cone/persons/resource/persons84049

Leo,  F
Research Group Cognitive Neuroimaging, Max Planck Institute for Biological Cybernetics, Max Planck Society;

Locator
There are no locators available
Fulltext (public)
There are no public fulltexts available
Supplementary Material (public)
There is no public supplementary material available
Citation

Leo, F., Bertini C, di Pellegrino, G., & Làdavas, E. (2008). Multisensory integration for orienting responses in humans requires the activation of the superior colliculus. Experimental Brain Research, 186(1), 67-77. doi:10.1007/s00221-007-1204-9.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0013-CA1D-6
Abstract
Animal studies have shown that the superior colliculus (SC) is important for synthesising information from multiple senses into a unified map of space. Here, we tested whether the SC is a critical neural substrate for multisensory spatial integration in humans. To do so, we took advantage of neurophysiological findings revealing that the SC does not receive direct projections from short-wavelength-sensitive S cones. In a simple reaction-time task, participants responded more quickly to concurrent peripheral (extra-foveal) audiovisual (AV) stimuli than to an auditory or visual stimulus alone, a phenomenon known as the redundant target effect (RTE). We show that the nature of this RTE was dependent on the colour of the visual stimulus. When using purple short-wavelength stimuli, to which the SC is blind, RTE was simply explained by probability summation, indicating that the redundant auditory and visual channels are independent. Conversely, with red long-wavelength stimuli, visible to the SC, the RTE was relate d to nonlinear neural summation, which constitutes evidence of integration of different sensory information. We also demonstrate that when AV stimuli were presented at fixation, so that the spatial orienting component of the task was reduced, neural summation was possible regardless of stimulus colour. Together, these findings provide support for a pivotal role of the SC in mediating multisensory spatial integration in humans, when behaviour involves spatial orienting responses.