May 2008
Volume 8, Issue 6
Free
Vision Sciences Society Annual Meeting Abstract  |   May 2008
Superior colliculus inactivation biases target selection for smooth pursuit, saccades, and manual responses
Author Affiliations
  • Richard Krauzlis
    Salk Institute for Biological Studies
  • Samuel Nummela
    Salk Institute for Biological Studies
Journal of Vision May 2008, Vol.8, 666. doi:10.1167/8.6.666
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      Richard Krauzlis, Samuel Nummela; Superior colliculus inactivation biases target selection for smooth pursuit, saccades, and manual responses. Journal of Vision 2008;8(6):666. doi: 10.1167/8.6.666.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Recent evidence implicates the superior colliculus (SC) in the selection of targets for saccades and pursuit, and also the control of covert visual attention. These findings raise the possibility that the SC supports target selection for any kind of response. We have now tested whether the SC supports target selection for manual responses as well as eye movements by reversibly inactivating the SC.

We evaluated target selection using a 2-alternative delayed match-to-sample task, with the target identified by a color cue presented at central fixation. On saccade trials, the target and distracter were presented in opposite hemifields at an eccentricity of 3.5°, slightly above or below the horizontal meridian. On pursuit trials, the stimuli initially appeared at similar locations but moved horizontally towards and across the center of the display. On manual response trials, the monkey viewed stimuli like those on saccade trials, but was required to maintain fixation and respond by button press. Blocks of saccade, pursuit, and manual response trials were interleaved before and after focal inactivation of SC by injection of muscimol (0.5 µl per injection, 5µg/µl).

Focal inactivation of the SC affected manual responses, though somewhat differently than eye movements. When the target was located in the region affected by the inactivation, the percentage of correct responses decreased for manual responses, as well as for saccades and pursuit. However, when the target was located out of the affected region, there was no change for manual responses, although performance improved for both pursuit and saccades.

These results show that SC inactivation causes a selection bias in favor of stimuli located outside of the affected region of retinotopic space, even when it results in an orienting movement towards the affected region (smooth pursuit) or a response that has nothing to do with orienting gaze (button press).

Krauzlis, R. Nummela, S. (2008). Superior colliculus inactivation biases target selection for smooth pursuit, saccades, and manual responses [Abstract]. Journal of Vision, 8(6):666, 666a, http://journalofvision.org/8/6/666/, doi:10.1167/8.6.666. [CrossRef]
Footnotes
 Supported by NIH EY012212.
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