Ard sweep of processing (Hopf et al., 2009). By measuring the magnitude: Unterschied zwischen den Versionen

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The authors hypothesize that the variations with prior studies, in which attention's impact enhanced in higher cortical places, might be due to the reality that they tested a wide variety of stimulus contrasts whereas preceding studies (e.g., Kastner et al., 1999; Maunsell Cook, 2002) had tested only a single, intermediate contrast. The authors remain agnostic concerning whether or not feed-forward or feedback activity underlies the comparable modulation across regions. Less is recognized concerning the neural mechanism for exogenous focus and its effects on stimulus processing. Psychophysical findings demonstrating that exogenous focus increases contrast ONX 0912 sensitivity suggest that it need to also enhance neural activity in early stages of visual processing. This hypothesis was tested by measuring brain activity in early visual regions working with speedy event-related fMRI in conjunction with a peripheral cueing paradigm to manipulate exogenous focus (Liu et al., 2005). Participants discriminated the orientation of one of two gratings preceded or followed by a non-predictive peripheral cue. Precueing the target place enhanced overall performance and created a bigger fMRI response in corresponding retinotopic regions. This enhancement progressively improved from striate to extrastriate regions. Thus, exogenous attention increases each perceptual efficiency along with the concomitant stimulus-evoked activity in early visual regions. These benefits deliver evidence concerning the retinotopically certain neural correlate for title= fpsyg.2016.01152 the effects of exogenous attention on early vision. Larger attentional effects in greater visual places have also been located in research of endogenous focus (e.g., Kastner et al., 1999; Maunsell Cook, 2002). Such a pattern is consistent with title= 2016/5789232 top-down modulation from frontal and parietal locations feeding back to the visual cortex, with diminishing effects in earlier visual regions. Even so, the attentional gradient could also be resulting from a feed-forward mechanism in which attentional modulation accumulates across sequential levels of processing. Whereas it has been established that endogenous (conceptually-driven) attention is mediated by a feedback mechanism (CorbettaNIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptVision Res. Author manuscript; offered in PMC 2012 July 05.CarrascoPageShulman, 2002; Desimone Duncan, 1995; Kanwisher Wojciulik, 2000; Kastner Ungerleider, 2000; Schroeder, Mehta, Foxe, 2001), a feed-forward mechanism appears extra probably within the case of transient (stimulus-driven) consideration. The attentional effect increases along the hierarchy of visual locations, from V1 to V4. For the reason that attention can boost the signal, its impact would be additional pronounced in extrastriate than striate areas.Ard sweep of processing (Hopf et al., 2009). By measuring the magnitude with the impact of interest more than title= srep30523 a wider variety of stimulus contrasts, in both event-related and mixed styles, two separate effects of focus have been identified in places V1 to V4: A rise in baseline activity, that is unlikely to improve functional discrimination, plus a contrast acquire effect that could serve a functional part in stimulus processing (Li et al., 2008). Escalating the contrast gain with the visual program shifts by far the most sensitive operating range with the technique toward reduced contrasts, hence improving the visual system's ability to determine these stimuli. The outcomes indicated that the magnitude in the attentional modulations was related for all locations tested. The authors hypothesize that the variations with previous research, in which attention's impact improved in larger cortical regions, might be due to the fact that they tested a wide range of stimulus contrasts whereas prior research (e.g., Kastner et al., 1999; Maunsell Cook, 2002) had tested only a single, intermediate contrast.