Determination of the proton environment of high stability Menasemiquinone intermediate in Escherichia coli nitrate reductase A by pulsed EPR.

Escherichia coli nitrate reductase A (NarGHI) is a membrane-bound enzyme that couples quinol oxidation at a periplasmically oriented Q-site (Q(D)) to proton release into the periplasm during anaerobic respiration. To elucidate the molecular mechanism underlying such a coupling, endogenous menasemiquinone-8 intermediates stabilized at the Q(D) site (MSQ(D)) of NarGHI have been studied by high-resolution pulsed EPR methods in combination with (1)H2O/2H2O exchange experiments. One of the two non-exchangeable proton hyperfine couplings resolved in hyperfine sublevel correlation (HYSCORE) spectra of the radical displays characteristics typical from quinone methyl protons.

Letter string processing and visual short-term memory.

The present study investigated whether expertise with letter string processing influences visual short-term memory capacity. Specifically, we examined whether performance in a change-detection task would vary as a function of stimulus type (letters vs. symbols) and type of display (horizontal, vertical, and circular).

Pitch-matching in poor singers: human model advantage.

Unlabelled: Previous studies on action imitation have shown an advantage for biological stimuli compared with nonbiological stimuli, possibly because of the role played by the mirror system. By contrast, little is known on whether such an advantage also takes place in the auditory domain, related to voice imitation.

Objectives/hypothesis: In this study, we wanted to test the hypothesis that auditory stimuli could be more accurately reproduced when the timbre is human than when the timbre is synthetic.

Age-related decline in sensory processing for locomotion and interception.

The ability to control locomotion through the environment and to intercept, or avoid objects is fundamental to the survival of all locomotor species. The extent to which this control relies upon optic flow, visual direction cues or non-visual sensory inputs has long been debated. Here we look at the use of sensory information in young and middle-aged participants using a locomotor-driven interceptive task.

Automatic detection and quantification of growth spurts.

Growth phenomena are often nonlinear and may contain spurts, characterized by a local increase in the rate of growth. Because measurement error and noise may produce apparent spurts, it is important to identify systematic and reliable spurts. We describe a system, automatic maxima detection (AMD), for statistically identifying significant spurts and computing (1) point of maximal velocity, when the spurt was most intense; (2) start, when the spurt started; (3) amplitude, the intensity of the spurt; and (4) duration, the length of the spurt.

Similar cerebral networks in language, music and song perception.

Two fMRI experiments were conducted using song to investigate the domain specificity of linguistic and musical processing. In Experiment 1, participants listened to pairs of spoken words, "vocalise" (i.e.

Insights into the control of arm movement during body motion as revealed by EMG analyses.

Recent studies have revealed that vestibulomotor transformations contribute to maintain the hand stationary in space during trunk rotation. Here we tested whether these vestibulomotor transformations have the same latencies and whether they are subject to similar cognitive control than the visuomotor transformations during manual tracking of a visual target. We recorded hand displacement and shoulder-muscle activity in two tasks: a stabilization task in which subjects stabilized their hand during passive 30 degrees body rotations, and a tracking task in which subjects tracked with their finger a visual target as it moved 30 degrees around them.

Watching the Word Go by: On the Time-course of Component Processes in Visual Word Recognition.

We describe a functional architecture for word recognition that focuses on how orthographic and phonological information cooperates in initial form-based processing of printed word stimuli prior to accessing semantic information. Component processes of orthographic processing and orthography-to-phonology translation are described, and the behavioral evidence in favor of such mechanisms is briefly summarized. Our theoretical framework is then used to interpret the results of a large number of recent experiments that have combined the masked priming paradigm with electrophysiological recordings.

Hydration and dispersion of C60 in aqueous systems: the nature of water-fullerene interactions.

The nature of fullerene-water interactions and the role that they play in the fate of C60 in aqueous systems is poorly understood. This work provides spectroscopic evidence for the surface hydroxylation of the initially hydrophobic C60 molecule when immersed in water. This mechanism appears to be the basis for stabilizing the hydrophilic nC60 aggregates in suspension.

Letter perception: from pixels to pandemonium.

In 1959, Oliver Selfridge proposed a model of letter perception, the Pandemonium model, in which the central hypothesis was that letters are identified via their component features. Although a consensus developed around this general approach over the years, key evidence in its favor remained lacking. Recent research has started to provide important evidence in favor of feature-based letter perception, describing the nature of the features, and the time-course of processes involved in mapping features onto abstract letter identities.

Effects of prime and target eccentricity on masked repetition priming.

Three experiments examined the influence of briefly presented, pattern-masked prime stimuli on target word recognition at varying eccentricities. The prime was either the same word as the targets or a different word, and prime position varied horizontally from a central fixation point. The targets were either in the same location as the primes (Experiment 1A) or always centrally located (Experiments 1B and 2).

I learned from what you did: Retrieving visuomotor associations learned by observation.

Observational learning allows individuals to acquire knowledge without incurring in the costs and risks of discovering and testing. The neural mechanisms mediating the retrieval of rules learned by observation are currently unknown. To explore this fundamental cognitive ability, we compared the brain responses when retrieving visuomotor associations learned either by observation or by individual learning.

Cancellation of a planned movement in monkey motor cortex.

Abruptly stopping a planned movement before it has even begun can be crucial to retarding a premature action. In the monkey motor cortex, we report herein that rapid cancellation of a prepared motor act involved the brief activation of neurons representing a movement in the opposite direction (anti-directional activity). When an expected GO signal failed to occur, this opposing anti-directional discharge appeared.