In order to avoid a discussion of whether brain activation related to spatial attention originated in the PMd or the FEF, we are going to focus on functionality and use the term “areas in DLFC associated with spatial attention” (ADSA) in
the following sections. Aiming to address the issue of brain activation in the ADSA during MOT, we implemented a control condition (LUM). Inhibitors,research,lifescience,medical LUM required paying attention to the moving objects while disregarding their trajectories, as opposed to previous fMRI studies on MOT that used passive viewing control conditions (Culham et al. 1998, 2001; Jovicich et al. 2001; Howe et al. 2009). That is, in both conditions, participants had to attend to peripherally presented visual stimuli, and both conditions featured the same amount of objects that moved around in the same visual field (the motion area, roughly 7° of visual angle). As a consequence, we can assume that processes of spatial attention are considerably Inhibitors,research,lifescience,medical involved in both tasks. Thus, by contrasting MOT against LUM, we should have accounted for respective activation in the ADSA. It is possible, though, that the two conditions differed in regard to spatial attentional load. While behavioral performance did Inhibitors,research,lifescience,medical not statistically differ, we cannot rule out this possibility. Rather, it appears to be intuitive to assume that MOT required more spatial attentional resources than LUM. However, Jovicich et al. (2001),
who explicitly used the MOT paradigm in order to manipulate attentional Inhibitors,research,lifescience,medical load, did not find any load-related activations
in the DLFC. That is, while possible differences in attentional load may have been manifest in other parts of the brain, we claim that it is unlikely that they can account for the activations in our target area. A more specific component of spatial attention that might have elicited different amounts of ADSA activation in MOT compared to LUM is shifts in spatial attention. Just as eye movement control, attention shifts can be categorized as endogenous, goal directed and exogenous, sensory guided. The extent to which the ADSA are involved in both categories Histone demethylase of spatial Inhibitors,research,lifescience,medical attention shifts is still under debate. For instance, Ptak and Schnider (2011) suggested that the ADSA are involved in both exogenous and endogenous attention shifts, whereas Corbetta and Shulman (2002) and Corbetta et al. (2005) claimed that the ADSA are rather responsible for endogenous, goal-directed attention shifts. In any case, remember that in the FEF-L task, upcoming target locations were visually guided (noncued), thus evoking exogenous shifts of attention. That is, after applying the this website exclusive FEF-L mask, any remaining attention-related activation in the MC can be ascribed to endogenous, goal-directed shifts in spatial attention. This interpretation would be in accordance with Yantis (1992), who proposed that maintenance of target identities is managed through top-down attention processes.