Parallel transmit (pTx) with online pulse design for task-based fMRI at 7 T.

Purpose: Parallel transmission (pTx) is an approach to improve image uniformity for ultra-high field imaging. In this study, we modified an echo planar imaging (EPI) sequence to design subject-specific pTx pulses online. We compared its performance against EPI with conventional circularly polarised (CP) pulses.

Correcting for Superficial Bias in 7T Gradient Echo fMRI.

The arrival of submillimeter ultra high-field fMRI makes it possible to compare activation profiles across cortical layers. However, the blood oxygenation level dependent (BOLD) signal measured by gradient echo (GE) fMRI is biased toward superficial layers of the cortex, which is a serious confound for laminar analysis. Several univariate and multivariate analysis methods have been proposed to correct this bias.

Improved motion correction of submillimetre 7T fMRI time series with Boundary-Based Registration (BBR).

Ultra-high field functional magnetic resonance imaging (fMRI) has allowed us to acquire images with submillimetre voxels. However, in order to interpret the data clearly, we need to accurately correct head motion and the resultant distortions. Here, we present a novel application of Boundary Based Registration (BBR) to realign functional Magnetic Resonance Imaging (fMRI) data and evaluate its effectiveness on a set of 7T submillimetre data, as well as millimetre 3T data for comparison.

Prospective motion correction improves the sensitivity of fMRI pattern decoding.

We evaluated the effectiveness of prospective motion correction (PMC) on a simple visual task when no deliberate subject motion was present. The PMC system utilizes an in-bore optical camera to track an external marker attached to the participant via a custom-molded mouthpiece. The study was conducted at two resolutions (1.

Adjudicating between face-coding models with individual-face fMRI responses.

The perceptual representation of individual faces is often explained with reference to a norm-based face space. In such spaces, individuals are encoded as vectors where identity is primarily conveyed by direction and distinctiveness by eccentricity. Here we measured human fMRI responses and psychophysical similarity judgments of individual face exemplars, which were generated as realistic 3D animations using a computer-graphics model.

Choosing the rules: distinct and overlapping frontoparietal representations of task rules for perceptual decisions.

Behavior is governed by rules that associate stimuli with responses and outcomes. Human and monkey studies have shown that rule-specific information is widely represented in the frontoparietal cortex. However, it is not known how establishing a rule under different contexts affects its neural representation.

The neural basis of eye gaze processing.

Humans are highly sensitive to another's gaze direction, and use this information to support a range of social cognitive functions. Here we review recent studies that have begun to delineate a neural system for gaze perception. We focus in particular on a set of core gaze processes: perceptual coding of another's eye gaze direction, which may involve anterior superior temporal sulcus (STS); gaze-cued attentional orienting, which may be mediated by lateral parietal regions; and the experience of joint attention with another individual, which recruits medial prefrontal cortex.

Strength of retinotopic representation of visual memories is modulated by strategy.

Human visual cortex shows retinotopic organization during both perception and attention, but whether this remains true for visual short-term memory (VSTM) is uncertain. In 2 functional magnetic resonance imaging experiments, we separated retinotopic activation during perception, attention, and VSTM maintenance. The 2 experiments differed in whether spatial encoding of the VSTM stimuli and prospective attention to the locations of the remembered items was encouraged or discouraged.

A head view-invariant representation of gaze direction in anterior superior temporal sulcus.

Humans show a remarkable ability to discriminate others' gaze direction, even though a given direction can be conveyed by many physically dissimilar configurations of different eye positions and head views. For example, eye contact can be signaled by a rightward glance in a left-turned head or by direct gaze in a front-facing head. Such acute gaze discrimination implies considerable perceptual invariance.

Direction-sensitive codes for observed head turns in human superior temporal sulcus.

Humans and other primates are adept at using the direction of another's gaze or head turn to infer where that individual is attending. Research in macaque neurophysiology suggests that anterior superior temporal sulcus (STS) contains a direction-sensitive code for such social attention cues. By contrast, most human functional Magnetic resonance imaging (fMRI) studies report that posterior STS is responsive to social attention cues.