Effects of unilateral dynamic handgrip on reaction time and error rate.

Quick and accurate reactions to environmental stimuli are often required. Researchers have investigated ways to improve these reactions, which are critical components of perceptual-motor abilities. To optimize individual performance, different techniques, such as embodied interventions and brain stimulation, have been examined. The evidence from EEG studies shows that upper limb muscle contractions lead to changes in brain oscillations associated with changes in mental states and behavioral outcomes. Much research has been conducted on whether muscle contractions of a particular hand have a greater effect on a perceptual-motor ability, as a trigger to facilitate cortical processes (a mediator) for skilled motor performance. While previous studies have shown that left- (vs. right-) hand contractions can lead to greater alpha activation, we hypothesized that left dynamic handgrips have different impacts on motor performance, reflected by simple RT (SRT) and choice RT (CRT). We recruited 64 right-handers, for a within/between-subjects experiment consisting of performance measurements in SRT and CRT tasks after the intervention (either right or left dynamic handgrip approximately twice a second for 30 s for each hand) or assignment to paired passive control groups. We did not find left-hand contractions improve response accuracy in neither SRT nor CRT tasks. Further, left-hand contractions did not affect RTs. The findings indicate that the effects of dynamic handgrips are smaller on behavioral outcomes such as RTs than what can be inferred from published studies. More research is needed to establish the effect of dynamic handgrips on optimizing performance.

The Impact of Skill Level on the Integration of Information and Post-Error Adjustment during Action Anticipation in Basketball.

The present study examined the impact of skill level on the integration of contextual prior information and kinematic information alongside post-error adjustment during action anticipation in basketball. Twenty-three collegiate basketball players and twenty-three control participants engaged in anticipating as quickly and accurately as possible the outcomes of free throws, utilizing video clips depicting basketball players' actions, both with and without contextual prior information. Anticipatory performance and the difference in anticipatory performance following errors and correct responses were analyzed based on skill level and the congruency of contextual prior information (none, congruent, and incongruent). The findings revealed that the congruency of contextual prior information significantly affects action anticipation, with skill level moderating this effect. Moreover, skill level influenced the congruency effect on accuracy discrepancies between post-error and post-correct trials during action anticipation, with controls showing greater sensitivity to previous trial performance compared to experts. These results provide further evidence for the notion that individuals employ Bayesian reliability-based strategies to integrate different information sources and underscore the role of skill level in adjusting anticipatory judgments following errors during action anticipation. These insights contribute to a deeper understanding of the cognitive and behavioral mechanisms that differentiate skill levels in action anticipation, potentially guiding the development of targeted training interventions.

Inter-individual, hemispheric and sex variability of brain activations during numerosity processing.

Numerosity perception is a fundamental and innate cognitive function shared by both humans and many animal species. Previous research has primarily focused on exploring the spatial and functional consistency of neural activations that were associated with the processing of numerosity information. However, the inter-individual variability of brain activations of numerosity perception remains unclear. In the present study, with a large-sample functional magnetic resonance imaging (fMRI) dataset (n = 460), we aimed to localize the functional regions related to numerosity perceptions and explore the inter-individual, hemispheric, and sex differences within these brain regions. Fifteen subject-specific activated regions, including the anterior intraparietal sulcus (aIPS), posterior intraparietal sulcus (pIPS), insula, inferior frontal gyrus (IFG), inferior temporal gyrus (ITG), premotor area (PM), middle occipital gyrus (MOG) and anterior cingulate cortex (ACC), were delineated in each individual and then used to create a functional probabilistic atlas to quantify individual variability in brain activations of numerosity processing. Though the activation percentages of most regions were higher than 60%, the intersections of most regions across individuals were considerably lower, falling below 50%, indicating substantial variations in brain activations related to numerosity processing among individuals. Furthermore, significant hemispheric and sex differences in activation location, extent, and magnitude were also found in these regions. Most activated regions in the right hemisphere had larger activation volumes and activation magnitudes, and were located more lateral and anterior than their counterparts in the left hemisphere. In addition, in most of these regions, males displayed stronger activations than females. Our findings demonstrate large inter-individual, hemispheric, and sex differences in brain activations related to numerosity processing, and our probabilistic atlas can serve as a robust functional and spatial reference for mapping the numerosity-related neural networks.

The Effect of Attentional Direction on Sub-Stages of Preparing for Motor Skill Execution Across Practice.

While several empirical studies using dual-task methodology have examined the effect of attentional direction on motor skill execution; few have studied the effect of attentional direction on just the preparation phase of motor practice. In this study, via a keying sequence paradigm, we explored processing stages of preparation for a motor skill and disentangled the effect of attentional direction on various stages across practice. First, participants learned two keying sequences (three versus six keys). Then, they practiced the keying sequences in response to corresponding sequence labels under two block-wise alternating dual-task conditions. To dissect the preparation phase into sequence selection and sequence initiation stages, participants received varying amounts of preparation time (0, 300, 900 ms) before a starting signal instructed them to begin sequence execution. In each trial, a tone was paired with one of the three or six keypresses, and participants indicated either the keypress with which the tone was presented (skill-focused dual task) or the tone's pitch (extraneous dual task) after the sequence execution. We found that attentional direction affected only the sequence selection stage, not the sequence initiation stage. During early practice, compared to drawing attention away from execution, directing attention toward execution led to faster sequence selection. This advantage decreased with practice and vanished during late blocks of trials. Moreover, for the execution phase, relative to directing attention toward execution, drawing attention away from execution led to better performance of keying sequence execution across practice. Thus, attentional direction alone does not fully explain the difference between performance patterns at different skill levels in the dual-task literature; rather, types of motor skills and dual task difficulty levels may also drive performance differences.

The Varying Effects of Dual Tasks on the Performance of Motor Skills across Practice.

Numerous previous studies using the dual-task methodology have indicated that the effect of attentional direction on the performance of motor skill differs as a function of skill levels. Whereas previous studies relied mostly on inter-individual comparisons, this study focused on how the effects of different attentional conditions change within individuals with practice. Participants were instructed to learn a short and a long keying sequence (three versus six keys) and then practiced under two block-wise alternating dual-task conditions. In each trial, a tone, either low- or high-pitched, was presented at one of the three/six keys and participants had to indicate either the pitch of the tone (extraneous dual task) or the key with which the tone was presented (skill-focused dual task) after finishing the execution of the keying sequence. Motor task performance was assessed by reaction time (RT) and movement duration (MD), and the concurrent cognitive task performance was assessed by the error rate. RT was faster in the skill-focused dual-task condition at the beginning of practice, whereas a generally shorter MD was found in the extraneous dual-task condition. The error rate in the extraneous dual task decreased with practice, whereas in the skill-focused dual task, it increased with practice. These results show that the effects of attentional direction differ not only as a function of the amount of practice but also as a function of the stage of information processing. Furthermore, our results indicate that the direction of attention alone does not explain the different patterns of performance at different skill levels seen across dual-task studies; rather, the skill levels, the nature of cognitive demands, the difficulty level of dual tasks, and the complexity of the motor skill could all drive performance differences.

Multisensory action effects facilitate the performance of motor sequences.

Research has shown that contingent, distinct action effects have a beneficial influence on motor sequence performance. Previous studies showed the beneficial influence of task-irrelevant action effects from one modality (auditory) on motor sequence performance, compared with no task-irrelevant action effects. The present study investigated the influence of task-irrelevant action effects on motor sequence performance from a multiple-modality perspective. We compared motor sequence performances of participants who received different task-irrelevant action effects in an auditory, visual, or audiovisual condition. In the auditory condition, key presses produced tones of a C-major scale that mapped to keys from left to right in ascending order. In the visual condition, key presses produced rectangles in different locations on the screen that mapped to keys from left to right in ascending order. In the audiovisual condition, both tone and rectangle effects were produced simultaneously by key presses. There were advantages for the audiovisual group in motor sequence initiation and execution. The results implied that, compared with unimodal action effects, action effects from multiple sensory modalities can prime an action faster and strengthen associations between successive actions, leading to faster motor sequence performance.

Dealing with failure: Prefrontal asymmetry predicts affective recovery and cognitive performance.

Individuals differ in how they deal with their emotions after failure. While some stay in a negative mood for hours, others recover quickly. The present study investigates whether prefrontal alpha asymmetry (PFA) influences affective recovery and cognitive performance following failure. Forty-seven participants completed two mental rotation tasks separated by a short break and received negative feedback on their performance. Electroencephalographic (EEG) data was collected before the first task and affective and cognitive changes were tracked using visual analogue scales throughout the experiment. In participants that felt upset, higher right-hemispheric PFA was associated with a persistence of negative affect. These participants showed poor performance on the second task. The findings suggest that PFA is a vulnerability factor that prevents individuals from regaining their initial affective state and impairs their cognitive performance.

Neural correlates of semantic and phonological processing revealed by functional connectivity patterns in the language network.

Semantics and phonology are fundamental components of language. Neuroimaging studies have identified a language network (LN) that is distributed through multiple regions and exhibits preferential responses to semantic and phonological information. However, it is unclear how these regions work collaboratively to support the processing of these components. In the present study, we first defined the LN as voxels that responded more to sentences than to strings of Chinese pseudo-characters. We subsequently used a voxel-based global brain connectivity method based on resting-state functional connectivity (FC) to characterize the neural correlates of semantic and phonological processing. We specifically correlated the within-network connectivity (WNC) of each voxel in the LN with the participants' scores on the semantic and phonological components extracted from a battery of reading tests via principal component analysis. We found that individuals with stronger WNC in the left posterior superior temporal gyrus (lpSTG) and anterior superior temporal gyrus (laSTG) were better at semantic and phonological processing, respectively. Furthermore, the FC of the lpSTG with the laSTG and bilateral fusiform gyrus mainly contributed to semantic processing, whereas the FC of the laSTG with the left posterior middle temporal gyrus and inferior frontal gyrus largely contributed to phonological processing. Importantly, the semantic and phonological subnetworks overlapped in the laSTG, the WNC of which correlated with the participants' performances during semantic-phonological interactions. Our study revealed the hub and subnetwork for semantic and phonological processing, respectively, and highlighted the role of the laSTG in semantic-phonological interactions.