For blood oxygenation level-dependent (BOLD) functional MRI experiments, contrast-to-noise ratio (CNR) increases with increasing field strength for both gradient echo (GE) and spin echo (SE) BOLD techniques. However, susceptibility artifacts and non-uniform coil sensitivity profiles complicate large field-of-view fMRI experiments (e.g., experiments covering multiple visual areas instead of focusing on a single cortical region). Here, we use SE BOLD to acquire retinotopic mapping data in early visual areas, testing the feasibility of SE BOLD experiments spanning multiple cortical areas at 7 Tesla. We also use a recently developed method for normalizing signal intensity in T 1 -weighted anatomical images to enable automated segmentation of the cortical gray matter for scans acquired at 7T with either surface or volume coils. We find that the CNR of the 7T GE data (average singlevoxel, single-scan stimulus coherence: 0.41) is almost twice that of the 3T GE BOLD data (average coherence: 0.25), with the CNR of the SE BOLD data (average coherence: 0.23) comparable to that of the 3T GE data. Repeated measurements in individual subjects find that maps acquired with 1.8 mm resolution at 3T and 7T with GE BOLD and at 7T with SE BOLD show no systematic differences in either the area or the boundary locations for V1, V2 and V3, demonstrating the feasibility of highresolution SE BOLD experiments with good sensitivity throughout multiple visual areas.

The current study demonstrated that hearing aid wearers can be trained on their front/back localization skills using either laboratory-based or home-based training program. The effectiveness of the training was generalized to other acoustic stimuli and the unaided conditions when the stimulus levels were fixed.

This study demonstrated that the use of the TNR algorithm would not negatively affect speech identification. The results also suggested that this algorithm may improve listening comfort in the presence of transient noise sounds and ensure consistent use of prescribed gain. Such an algorithm may ensure more consistent audibility across listening environments.

Contour detection is a crucial component of visual processing; however, performance on contour detection tasks can vary depending on the context of the visual scene. S. C. Dakin and N. J. Baruch (2009) showed that detection of a contour in an array of distracting elements depends on the orientation of flanking elements. Here, using a line of five collinear Gabor elements (“target contour”) in a field of distractor Gabor elements, we systematically measured the effects of eccentricity, spacing, and spatial frequency on contour detection performance in three different contexts: randomly oriented distractors (control condition), flanking distractors (on either side of the collinear Gabors) aligned approximately parallel to the target contour, and flanking distractors aligned approximately orthogonal to the target contour. In the control condition, contour detection performance was best for larger Gabors (2 cpd) spaced farther apart (1.2°). Parallel flankers reduced performance for intermediate and large spacings and sizes compared to the control condition, while orthogonal flankers increased performance for the smallest spacing and size compared to the control condition. The results are fit by a model in which collinear facilitation, which is size-dependent but can persist for several degrees of visual angle, competes with orientation-dependent suppression from the flanking context when elements are separated by less than a degree of visual angle.

The blood oxygenation level-dependent (BOLD) functional MRI response to suppressive neural activity has not been tested on a fine spatial scale. Using Gabor patches placed in the near periphery, we precisely localized individual regions of interest in primary visual cortex and measured the response at a range of contrasts in two different contexts: with parallel and with orthogonal flanking Gabor patches. Psychophysical measurements confirmed strong suppression of the target Gabor response when flanked by parallel Gabors. However, the BOLD response to the target with parallel flankers decreased as the target contrast increased, which contradicts psychophysical estimates of local neural activity.