Alpha frontal asymmetry underlies individual differences in reactivity to acute psychosocial stress in males.

People vary in their responses to stress. The present study aimed to investigate whether and how alpha frontal asymmetry (AFA) measured in the resting state underlies the individual differences in psychological responses to acute psychosocial stress (e.g., increases in heart rate and cortisol) induced by the Trier social stress test. Forty-three healthy male adults were enrolled in this study. The results showed that the AFA score negatively predicted both heart rate and cortisol responses, that is relatively higher right-frontal activity during the resting state was related to a stronger physiological stress response. These results indicated that higher withdrawal motivation or effortful control is associated with a higher physiological stress response, which suggested that AFA in the resting state can serve as a biological predictor of acute stress responses in men.

Interresidue carbonyl-carbonyl polarization transfer experiments in uniformly 13C,15N-labeled peptides and proteins.

In this work, we demonstrate that Homonuclear Rotary Resonance Recoupling (HORROR) can be used to reintroduce carbonyl-carbonyl interresidue dipolar interactions and to achieve efficient polarization transfer between carbonyl atoms in uniformly (13)C,(15)N-labeled peptides and proteins. We show that the HORROR condition is anisotropically broadened and overall shifted to higher radio frequency intensities because of the CSA effects. These effects are analyzed theoretically using Average Hamiltonian Theory. At spinning frequencies used in this study, 22kHz, this broadening is experimentally found to be on the order of a kilohertz at a proton field of 600MHz. To match HORROR condition over all powder orientations, variable amplitude radio frequency (RF) fields are required, and efficient direct transfers on the order of 20-30% can be straightforwardly established. Two- and three-dimensional chemical shift correlation experiments establishing long-range interresidue connectivities (e.g., (N[i]-CO[i-2])) are demonstrated on the model peptide N-acetyl-valine-leucine, and on the third immunoglobulin binding domain of protein G. Possible future developments are discussed.

Resolution enhancement by homonuclear J-decoupling: application to three-dimensional solid-state magic angle spinning NMR spectroscopy.

We describe a simple protocol to achieve homonuclear J-decoupling in the indirect dimensions of multidimensional experiments, and to enhance spectral resolution of the backbone Calpha carbons in the 3D NCACX experiment. In the proposed protocol, the refocusing of the Calpha-CO homonuclear J-couplings is achieved by applying an off-resonance selective pi pulse to the CO spectral region in the middle of Calpha chemical shift evolution. As is commonly used in solution NMR, a compensatory echo period is used to refocus the unwanted chemical shift evolution of Calpha spins, which takes place during the off-resonance selective pulse. The experiments were carried out on the beta1 immunoglobulin binding domain of protein G (GB1). In GB1, such implementation results in significantly reduced line widths, and leads to an overall sensitivity enhancement.

Dipolar chemical shift correlation spectroscopy for homonuclear carbon distance measurements in proteins in the solid state: application to structure determination and refinement.

High-resolution solid-state NMR spectroscopy has become a promising tool for protein structure determination. Here, we describe a new dipolar-chemical shift correlation experiment for the measurement of homonuclear 13C-13C distances in uniformly 13C,15N-labeled proteins and demonstrate its suitability for protein structure determination and refinement. The experiments were carried out on the beta1 immunoglobulin binding domain of protein G (GB1). Both intraresidue and interresidue distances between carbonyl atoms and atoms in the aliphatic side chains were collected using a three-dimensional chemical shift correlation spectroscopy experiment that uses homogeneously broadened rotational resonance recoupling for carbon mixing. A steady-state approximation for the polarization transfer function was employed in data analysis, and a total of 100 intramolecular distances were determined, all in the range 2.5-5.5 A. An additional 41 dipolar contacts were detected, but the corresponding distances could not be accurately quantified. Additional distance and torsional restraints were derived from the proton-driven spin diffusion measurements and from the chemical shift analysis, respectively. Using all these restraints, it was possible to refine the structure of GB1 to a root-mean square deviation of 0.8 A. The approach is of general applicability for peptides and small proteins and can be easily incorporated into a structure determination and refinement protocol.

(13)C-(13)C distance measurements in U-(13)C, (15)N-labeled peptides using rotational resonance width experiment with a homogeneously broadened matching condition.

In this publication, we introduce a version of the rotational resonance width experiment with a homogeneously broadened matching condition. The increase in the bandwidth is achieved by the reduction of the proton decoupling power during mixing, which results in the reduction of zero-quantum relaxation, and broadens the rotational resonance condition. We show that one can achieve recoupling of the carbonyl-aliphatic side chain dipolar interactions band selectively, while avoiding the recoupling of strongly interacting C'-Calpha and C'-Cbeta spin pairs. The attenuation of the multi-spin effects in the presence of short zero-quantum relaxation enables a two-spin approximation to be employed for the analysis of the experimental data. The systematic error introduced by this approximation is estimated by comparing the results with a three-spin simulation. The experiment is demonstrated in [U-(13)C,(15)N]N-acetyl-L-Val-L-Leu dipeptide, where 11 distances, ranging from 2.5 to 6 A, were measured.

[Differential visual attention scales directed by location versus semantic cue].

OBJECTIVE: To compare the cortical mechanisms associated with visual spatial attention directed by location cues and Chinese character cues. METHOD: Eleven healthy adults (mean age=19) with normal vision served as the subjects. In experiment I, the cue was a circle with black solid line. There were three cue sizes: small, medium and large. In experiment II, three black concentric circles were presented as background, their diameters were the same as the three cues used in experiment I. The cue was one of three Chinese characters small, medium or large respectively. The task of the subjects was to discriminate the target's orientation. RESULT: RT in experiment II was longer with short ISI. The anterosuperior N1 amplitude elicited by the cue in experiment II was larger than that in experiment I. The inferoposterior P1 latency in experiment II was longer than that in experiment I. Comparing the target evoked ERP, the inferoposterior P1 and N1, latency of experiment II was longer than that in experiment I, the inferoposterior P2 amplitude in experiment II was larger than that in experiment I. CONCLUSION: The processing of Chinese cue takes place at higher level functional brain regions compared to processing of location cue. The later requires more resource in the earlier stage of cue process and less in the subsequent stage of the task.

[Brain processing component during face cognition--N170 revealed by event-related potentials].

Objective. To observe features of early component N170 during face recognition. Method. Scalp distribution, amplitude, and latency of N170 was recorded during face recognition tasks in 16 normal subjects. Result. N170 was elicited by the face stimuli in only half of the subjects and the amplitude was modulated by cognitive tasks. Conclusion. N170 reflects not only face structure encoding unit but also direct visual processing unit. Whether N170 reflects the specialty in face recognition needs further study. The latency of N170 showed left hemisphere dominance and the amplitude showed right hemisphere dominance, indicating that it is not pure right hemisphere dominance in face recognition.

[The mechanism of gain in scale of visual attention].

Objective. To compare the cortical mechanisms associated with the visual spatial attention directed by fixed location cues. Method. The subjects were 12 healthy right-handed young volunteers. The visual stimuli were presented with the sequence as: background-cue-target. The cue was a black circle varied in three different sizes randomly. The foci of the circles were always at the center of the screen. The task of the subjects was to search the target within the cue circle and discriminate its orientation. Electroencephalogram (EEG) was recorded from 128 scalp sites. Result. The reaction time (RT) to the targets in the same location shortened when the cue size enlarged. The target evoked P1 and N1 components were not affected by the attentive region size, while the amplitudes of the inferoposterior P2 and anterosuperior N2 enlarged when the attentive region size enlarged. Conclusion. 1) The P1 and N1 components under visual attention were related to the spatial location processes mainly. 2) Cue-evoked P2 and N2 components were related to the size of attentive region. 3) The processes of spatial location information were earlier than attentive scale information, which supported the theory that spatial selection is a prerequisite for correct processes of visual object information.