Article

The Saccadic Re-Centering Bias is Associated with Activity Changes in the Human Superior Colliculus

Center for Cognitive Neuroscience, Duke University Durham, NC, USA.
Frontiers in Human Neuroscience (Impact Factor: 2.9). 11/2010; 4:193. DOI: 10.3389/fnhum.2010.00193
Source: PubMed

ABSTRACT Being able to effectively explore our visual world is of fundamental importance, and it has been suggested that the straight-ahead gaze (primary position) might play a special role in this context. We employed fMRI in humans to investigate how neural activity might be modulated for saccades relative to this putative default position. Using an endogenous cueing paradigm, saccade direction and orbital starting position were systematically manipulated, resulting in saccades toward primary position (centripetal) and away from primary position (centrifugal) that were matched in amplitude, directional predictability, as well as orbital starting position. In accord with earlier research, we found that fMRI activity in the superior colliculus (SC), as well as in the frontal eye fields and the intraparietal sulcus, was enhanced contralateral to saccade direction across all saccade conditions. Furthermore, the SC exhibited a relative activity decrease during re-centering relative to centrifugal saccades, a pattern that was paralleled by faster saccadic reaction times. In contrast, activity within the cortical eye fields was not significantly modulated during re-centering saccades as compared to other saccade types, suggesting that the re-centering bias is predominantly implemented at a subcortical rather than cortical processing stage. Such a modulation might reflect a special coding bias facilitating the return of gaze to a default position in the gaze space in which retinotopic and egocentric reference frames are aligned and from which the visual world can be effectively explored.

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Available from: Mircea Ariel Schoenfeld, Aug 22, 2015
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    • "Despite these difficulties, it has been possible to retinotopically map the human SC (DuBois and Cohen 2000; Katyal et al. 2010; Schneider and Kastner 2005), record visual responses to static and moving stimuli (Schneider and Kastner 2005; Sylvester et al. 2007), and demonstrate attentional modulations (Gitelman et al. 2002; Himmelbach et al. 2007; Katyal et al. 2010; Schneider and Kastner 2009), all with functional magnetic resonance imaging (fMRI). However, despite the critical role the SC plays in oculomotor control, very few studies have attempted to record oculomotor signals from the human SC (Anderson et al. 2008; Krebs et al. 2010a, 2010b; Petit and Beauchamp 2003). This may in part be due to the further technical challenges faced when attempting to record eye movement responses within a high magnetic field. "
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