However, the absence of saccade occurrences during


However, the absence of saccade occurrences during

MOT might point toward the employment of saccade inhibition processes (e.g., Culham et al. 1998). The significance of the FEF for the inhibition of exogenous, visually guided saccades has been a matter of debate. While there have been studies suggesting the FEF to be crucially involved in oculomotor-related inhibitory processes Inhibitors,research,lifescience,medical (Connolly et al. 2000; Kimmig et al. 2001; Pierrot-Deseilligny et al. 2004), it is noteworthy that the inhibition of exogenous saccades is usually measured by means of the “antisaccade paradigm.” This paradigm requires the performance of saccades toward the direction opposite to the locus of appearance of a 3-Methyladenine in vitro visual object. Thus, result interpretation regarding the neural substrates of saccade inhibition based on this paradigm, where saccade suppression (toward the target), computation of the target’s mirror position, and saccade execution (toward said mirror position) are confounded, is Inhibitors,research,lifescience,medical problematic. In line with this

reasoning, there have been clinical findings painting a less clear picture of FEF involvement in inhibitory oculomotor control (Gaymard et al. 1999). A paradigm allowing for a Inhibitors,research,lifescience,medical more valid comparison with assumed eye movement inhibition in our MOT task would be saccade suppression during fixation with concurrently appearing peripheral visual stimuli. Neggers et al. (2012) tested this paradigm, the contrast of [Fixation with Peripheral Stimuli > Fixation without Peripheral Stimuli] revealing the following activation maxima (MNI, x/y/z): −38/−6/52, −52/0/38, 44/−2/52. As Inhibitors,research,lifescience,medical these activations are at the most tangentially overlapping

with the activations found in the DLFC in our MC (maxima: −15/−10/67, 21/−10/61), we are confident that our allegedly found PMd activation did not originate from oculomotor suppression during visual fixation. Spatial attention and the DLFC Aside from oculomotor control, prior fMRI studies on MOT attributed activation in the DLFC to spatial attention during visual search (Culham et al. 1998, 2001; Jovicich et al. 2001; Howe et Inhibitors,research,lifescience,medical al. 2009). Indeed, brain activation related to spatial attention has been previously ascribed to the FEF (Corbetta 1998; Zacks et al. 2001), suggesting a strong link between the government of spatial attention and oculomotor control (“premotor theory of attention,” Rizzolatti et al. 1987). Other studies that found PD184352 (CI-1040) activation in the DLFC during the performance of spatial attention tasks have implicated the PMd as the region of origin. Boussaoud (2001), for instance, suggested that there are two subdivisions of the PMd, a rostral and a caudal part, that are rather distinct in regard to their functionality. While the caudal part appeared to be primarily involved in movement planning, the rostral part seemed to be mainly associated with the maintenance of spatial stimulus representations (Simon et al. 2002).

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