To this end we compared BOLD responses Roxadustat cost evoked by search in the same parts of the VF, while having the eyes in different orientations relative to the head; conversely, by keeping non-eye-centred locations during search constant, while varying the position of search items within the VF. Our results suggest that both the IPS and the right FEF contribute to visual search by using eye-centred coding. Fourteen right-handed and one left-handed subject (mean age 27.1 years; six female, nine male; with normal or corrected-to-normal visual acuity, using scanner-compatible
glasses) participated in this study, which was approved by the Ethics Review Board of the Medical Faculty of Tübingen University. Hence, this study fully conforms with the code of ethics of the World Medical Association [Declaration of Helsinki; see Br Med J (July 1964), 818]. Each subject provided her/his written informed consent and was compensated financially for her/his participation. The subjects had to perform a task of covert
visual search in a mixed-block/event-related fMRI setting. Visual stimuli were presented onto a screen positioned frontoparallel to the subjects lying supine in the scanner. Using a beamer (NEC GT 950 1024 × 768 pixel) the stimuli were back-projected from outside the scanner room onto a mirror directing the beam parallel to the bore and centred onto a semi-opaque (diameter 60 cm) screen in the darkened scanner. The subjects were able to view the screen using a mirror system attached to the Alpelisib cell line Pregnenolone head-coil at a viewing distance of 70 cm. Stimulus presentations and data recording were controlled by a program written in LabView. Each trial consisted
of three epochs, as shown in Fig. 1B. After a randomly varied fixation period of 500–2500 ms [the white fixation point (diameter 0.35°) was either projected straight ahead, 10° to the right or left on the black screen], subjects were exposed to a search array in either their right or left visual hemifield. The array had a width of 3° (height 8°) visual angle and was placed with its centre at 5° eccentricity to the left or right of the fixation point. The array consisted of six ‘L’-shaped items (each 1.2° × 1.2°). A singular ‘L’ of conventional orientation, present in 50% of the trials, served as the target. The other items in the field, serving as distractors, were ‘L’s of non-conventional orientation obtained by mirroring a normal ‘L’ at one of the cardinal axes. Subjects had 3000 ms to decide whether the target was present in the array or not, while keeping fixation. At the end of this search period, the fixation dot disappeared and, at the same time, two response targets appeared on the vertical meridian, 4° above and below the centre.