Distinct neural mechanisms support inner speaking and inner hearing.

Humans have the ability to mentally examine speech. This covert form of speech production is often accompanied by sensory (e.g.

Phoneme Representation and Articulatory Impairment: Insights from Adults with Comorbid Motor Coordination Disorder and Dyslexia.

Phonemic processing skills are impaired both in children and adults with dyslexia. Since phoneme representation development is based on articulatory gestures, it is likely that these gestures influence oral reading-related skills as assessed through phonemic awareness tasks. In our study, fifty-two young dyslexic adults, with and without motor impairment, and fifty-nine skilled readers performed reading, phonemic awareness, and articulatory tasks.

Stronger impulse capture and impaired inhibition of prepotent action in children with ADHD performing a Simon task: An electromyographic study.

Objective: A deficit in interference control is commonly reported in children with attention deficit hyperactivity disorder (ADHD). This has mainly been interpreted as a difficulty in inhibiting inappropriate responses. However, it could be due to at least two distinct and independent processes, which are often confounded: The activation or suppression of impulsive responses.

Centroparietal activity mirrors the decision variable when tracking biased and time-varying sensory evidence.

Decision-making is a fundamental human activity requiring explanation at the neurocognitive level. Current theoretical frameworks assume that, during sensory-based decision-making, the stimulus is sampled sequentially. The resulting evidence is accumulated over time as a decision variable until a threshold is reached and a response is initiated.

The Neurodynamic Decision Variable in Human Multi-alternative Perceptual Choice.

The neural dynamics underpinning binary perceptual decisions and their transformation into actions are well studied, but real-world decisions typically offer more than two response alternatives. How does decision-related evidence accumulation dynamically influence multiple action representations in humans? The heightened conservatism required in multiple compared with binary choice scenarios suggests a mechanism that compensates for increased uncertainty when multiple choices are present by suppressing baseline activity. Here, we tracked action representations using corticospinal excitability during four- and two-choice perceptual decisions and modeled them using a sequential sampling framework.

Neurodynamic Evidence Supports a Forced-Excursion Model of Decision-Making under Speed/Accuracy Instructions.

Evolutionary pressures suggest that choices should be optimized to maximize rewards, by appropriately trading speed for accuracy. This speed-accuracy tradeoff (SAT) is commonly explained by variation in just the baseline-to-boundary distance, i.e.

An independent, landmark-dominated head-direction signal in dysgranular retrosplenial cortex.

We investigated how landmarks influence the brain's computation of head direction and found that in a bidirectionally symmetrical environment, some neurons in dysgranular retrosplenial cortex showed bidirectional firing patterns. This indicates dominance of neural activity by local environmental cues even when these conflicted with the global head direction signal. It suggests a mechanism for associating landmarks to or dissociating them from the head direction signal, according to their directional stability and/or utility.

Beyond decision! Motor contribution to speed-accuracy trade-off in decision-making.

Both in real life and experimental settings, increasing response speed typically leads to more error-prone actions. Processes underlying such a "speed-accuracy trade-off" (SAT) are usually assumed to be purely decisional: cautiousness would be determined only by the amount of sensory evidence required to select a response. The present data challenges this largely accepted view, by directly showing that motor processes are speeded up under time pressure.

Preventing (impulsive) errors: Electrophysiological evidence for online inhibitory control over incorrect responses.

In a rich environment, with multiple action affordances, selective action inhibition is critical in preventing the execution of inappropriate responses. Here, we studied the origin and the dynamics of incorrect response inhibition and how it can be modulated by task demands. We used EEG in a conflict task where the probability of compatible and incompatible trials was varied.

Spatial and temporal resolutions of EEG: Is it really black and white? A scalp current density view.

Among the different brain imaging techniques, electroencephalography (EEG) is classically considered as having an excellent temporal resolution, but a poor spatial one. Here, we argue that the actual temporal resolution of conventional (scalp potentials) EEG is overestimated, and that volume conduction, the main cause of the poor spatial resolution of EEG, also distorts the recovered time course of the underlying sources at scalp level, and hence degrades the actual temporal resolution of EEG. While Current Source Density (CSD) estimates, through the Surface Laplacian (SL) computation, are well known to dramatically reduce volume conduction effects and hence improve EEG spatial resolution, its positive impact on EEG temporal resolution is much less recognized.

Linking EEG signals, brain functions and mental operations: Advantages of the Laplacian transformation.

Electroencephalography (EEG) is a very popular technique for investigating brain functions and/or mental processes. To this aim, EEG activities must be interpreted in terms of brain and/or mental processes. EEG signals being a direct manifestation of neuronal activity it is often assumed that such interpretations are quite obvious or, at least, straightforward.

Controlling your impulses: electrical stimulation of the human supplementary motor complex prevents impulsive errors.

To err is human. However, an inappropriate urge does not always result in error. Impulsive errors thus entail both a motor system capture by an urge to act and a failed inhibition of that impulse.

Distributional reaction time properties in the Eriksen task: marked differences or hidden similarities with the Simon task?

In conflict tasks, the irrelevant stimulus attribute needs to be suppressed for the correct response to be produced. In the Simon task, earlier researchers have proposed that this suppression is the reason that, after an initial increase, the interference effect decreases for longer RTs, as reflected by late, negative-going delta plots. This view has been challenged by observations of positive-going delta plots, even for long RTs, in other conflict tasks, despite a similar necessity for suppression.

Corticospinal control of wrist muscles during expectation of a motor perturbation: a transcranial magnetic stimulation study.

Voluntary movement is often perturbed by the external forces in the environment. Because corticospinal (CS) control of wrist muscles during preparation of voluntary movement has been extensively studied without variation in the external forces, very little is known about the way CS control adapts when subjects expect motor perturbations. Here, we studied the CS control of wrist muscles during expectation of an imposed wrist extension.