Experience Affects EEG Event-Related Synchronization in Dancers and Non-dancers While Listening to Preferred Music

EEGs were analyzed to investigate the effect of experiences in listening to preferred music in dancers and non-dancers. Participants passively listened to instrumental music of their preferred genre for 2 min (Argentine tango for dancers, classical, or jazz for non-dancers), alternate genres, and silence. Both groups showed increased activity for their preferred music compared to non-preferred music in the gamma, beta, and alpha frequency bands. The results suggest all participants' conscious recognition of and affective responses to their familiar music (gamma), appreciation of the tempo embedded in their preferred music and emotional arousal (beta), and enhanced attention mechanism for cognitive operations such as memory retrieval (alpha). The observed alpha activity is considered in the framework of the alpha functional inhibition hypothesis, in that years of experience listening to their favorite type of music may have honed the cerebral responses to achieve efficient cortical processes. Analyses of the electroencephalogram (EEG) activity over 100s-long music pieces revealed a difference between dancers and non-dancers in the magnitude of an initial alpha event-related desynchronization (ERD) and the later development of an alpha event-related synchronization (ERS) for their preferred music. Dancers exhibited augmented alpha ERD, as well as augmented and uninterrupted alpha ERS over the remaining 80s. This augmentation in dancers is hypothesized to be derived from creative cognition or motor imagery operations developed through their dance experiences.

EXPRESS: Distraction by auditory novelty during reading: Evidence for disruption in saccade planning, but not saccade execution

Novel or unexpected sounds that deviate from an otherwise repetitive sequence of the same sound cause behavioural distraction. Recent work has suggested that distraction also occurs during reading as fixation durations increased when a deviant sound was presented at the fixation onset of words. The present study tested the hypothesis that this increase in fixation durations occurs due to saccadic inhibition. This was done by manipulating the temporal onset of sounds relative to the fixation onset of words in the text. If novel sounds cause saccadic inhibition, they should be more distracting when presented during the second half of fixations when saccade programming usually takes place. Participants read single sentences and heard a 120 ms sound when they fixated five target words in the sentence. On most occasions (p= 0.9), the same sine wave tone was presented (“standard”), while on the remaining occasions (p= 0.1) a new sound was presented (“novel”). Critically, sounds were played either during the first half of the fixation (0 ms delay) or during the second half of the fixation (120 ms delay). Consistent with the saccadic inhibition hypothesis, novel sounds led to longer fixation durations in the 120 ms compared to the 0 ms delay condition. However, novel sounds did not generally influence the execution of the subsequent saccade. These results suggest that unexpected sounds have a rapid influence on saccade planning, but not saccade execution.

The Quiet Eye and Expertise: Sustained Fixations Do Not Transfer to Unpracticed Throws Among Expert Dart Players

The length of the last visual fixation before the critical final phase of a movement—the quiet eye (QE) fixation—is positively correlated with expertise and success. The present study tested the potential for intraskill transfer of QE durations in order to determine whether it is intrinsically linked to expertise development or is a separable skill that may be employed to improve performance under novel circumstances. The authors tracked highly skilled dart throwers’ gazes while they executed familiar (highly practiced) and familiar yet novel (distance/effector-modified) sport-specific actions. QE duration was significantly reduced when performing in unfamiliar conditions, suggesting that QE does not transfer to atypical conditions and may therefore be a result of—rather than a contributor to—expertise development. These results imply that intraskill transfer of QE is limited and, consistent with the inhibition hypothesis of QE development, argue against the value of teaching QE as an independent means of improving performance.

The role of the C2A domain of synaptotagmin 1 in asynchronous neurotransmitter release

Following nerve stimulation, there are two distinct phases of Ca2+-dependent neurotransmitter release: a fast, synchronous release phase, and a prolonged, asynchronous release phase. Each of these phases is tightly regulated and mediated by distinct mechanisms. Synaptotagmin 1 is the major Ca2+ sensor that triggers fast, synchronous neurotransmitter release upon Ca2+ binding by its C2A and C2B domains. It has also been implicated in the inhibition of asynchronous neurotransmitter release, as blocking Ca2+ binding by the C2A domain of synaptotagmin 1 results in increased asynchronous release. However, the mutation used to block Ca2+ binding in the previous experiments (aspartate to asparagine mutations, sytD-N) had the unintended side effect of mimicking Ca2+ binding, raising the possibility that the increase in asynchronous release was an artifact of ostensibly constitutive Ca2+ binding. To directly test this C2A inhibition hypothesis, we utilized an alternate C2A mutation that we designed to block Ca2+ binding without mimicking it (an aspartate to glutamate mutation, sytD-E). Analysis of both the original sytD-N mutation and our alternate sytD-E mutation at the Drosophila neuromuscular junction showed differential effects on asynchronous release, as well as on synchronous release and the frequency of spontaneous release. Importantly, we found that asynchronous release is not increased in the sytD-E mutant. Thus, our work provides new mechanistic insight into synaptotagmin 1 function during Ca2+-evoked synaptic transmission and demonstrates that Ca2+ binding by the C2A domain of synaptotagmin 1 does not inhibit asynchronous neurotransmitter release in vivo.Significance statementThis study provides mechanistic insights into synaptotagmin function during asynchronous neurotransmitter release and supports a dramatically different hypothesis regarding the mechanisms triggering asynchronous vesicle fusion. Using two distinct C2A mutations that block Ca2+ binding, we report opposing effects on synchronous, spontaneous, and asynchronous neurotransmitter release. Importantly, our data demonstrate that Ca2+ binding by the C2A domain of synaptotagmin does not regulate asynchronous release and thus disprove the current inhibition hypothesis. We propose a spatial competition hypothesis to explain these seemingly discordant results of the differing C2A Ca2+ binding mutations.

Picking an apple from a tree: Response-selection demands, inhibition requirements, and the functionality of the Quiet Eye in a far-aiming task

In the study of the mutual coupling between perception and action, the performance-enhancing effect of the last fixation before movement initiation, the Quiet Eye (QE), has been repeatedly shown. To the explanation of this phenomenon, among others, an inhibition hypothesis was formulated which suggests that the parametrisation of the optimal task solution is shielded against non-optimal task solutions. In this study, a prediction of this hypothesis was tested by manipulating response-selection demands over movement preparation in a targeting task which required to throw balls as accurate as possible at virtual target discs. Participants in the group with high response-selection demands always had to select one out of four targets, whereas the selection for the participants in the group with low response-selection demands was yoked to the selection of the other group. The results showed the predicted longer QE durations for the high response-selection demands group that, particularly, emanated from earlier QE onsets. Because of similar throwing demands, these differences cannot merely be explained by differences in the fine-tuning of the motor response but provide evidence for the suggested inhibition function. Particularly, with high response-selection demands, the parametrisation of the non-selected targets over movement preparation had to be inhibited. Descriptively, differences in the QE offset suggest that these shielding requirements persisted over movement control. This study extends earlier work on the theoretical foundation of the QE phenomenon and provides fruitful insights into its underlying mechanisms.

Acid induced reduction of the glycaemic response to starch-rich foods: the salivary α-amylase inhibition hypothesis

Acid-inhibition of salivary α-amylase resulted in the interruption of starch release by 50% and interruption of amylolysis into oligosaccharides.

Sensitivity analysis of six soil organic matter models applied to the decomposition of animal manures and crop residues

Two features distinguishing soil organic matter simulation models are the type of kinetics used to calculate pool decomposition rates, and the algorithm used to handle the effects of N shortage on C decomposition. Compared to widely used first-order kinetics, Monod kinetics more realistically represent organic matter decomposition, because they relate decomposition to both substrate and decomposer size. Most models impose a fixed C to N ratio for microbial biomass. When N required by microbial biomass to decompose a given amount of substrate- C is larger than soil available N, carbon decomposition rates are limited proportionally to N deficit (N inhibition hypothesis). Alternatively, C-overflow was proposed as a way of getting rid of excess C, by allocating it to a storage pool of polysaccharides. We built six models to compare the combinations of three decomposition kinetics (first-order, Monod, and reverse Monod), and two ways to simulate the effect of N shortage on C decomposition (N inhibition and C-overflow). We conducted sensitivity analysis to identify model parameters that mostly affected CO₂ emissions and soil mineral N during a simulated 189-day laboratory incubation assuming constant water content and temperature. We evaluated model outputs sensitivity at different stages of organic matter decomposition in a soil amended with three inputs of increasing C to N ratio: liquid manure, solid manure, and low-N crop residue. Only few model parameters and their interactions were responsible for consistent variations of CO₂ and soil mineral N. These parameters were mostly related to microbial biomass and to the partitioning of applied C among input pools, as well as their decomposition constants. In addition, in models with Monod kinetics, CO₂ was also sensitive to a variation of the halfsaturation constants. C-overflow enhanced pool decomposition compared to N inhibition hypothesis when N shortage occurred. Accumulated C in the polysaccharides pool decomposed slowly; therefore model outputs were not sensitive to a variation of its decay constant. Six-month organic matter decomposition was generally higher for models implementing classical Monod kinetics, followed by models with first-order and reverse Monod kinetics, due to the effect of soil microbial biomass growth on decomposition rates. Moreover, models implementing Monod kinetics predicted positive priming effects of native organic matter after soil amendment, according to co-metabolism theory. Thus, priming was proportional to the increase of the microbial biomass and in turn to the decomposability of applied organic matter. We conclude that model calibration should focus only on the few important parameters.