Experimental Brain Research最新文献

We examined the impact of auditory stimuli and their methods on a dynamic balance task performance. Twenty-four young adults wore an HTC Vive headset and dodged a virtual ball to the right or left based on its color (blue to the left, red to the right, and vice versa). We manipulated the environment by introducing congruent (auditory stimuli from the correct direction) or incongruent (auditory stimuli played randomly from either side) and comparing a multimodal (visual and congruent auditory stimuli) to unimodal (visual or auditory stimuli) presentation. We tested four apparatuses: loudspeakers, headphones, passthrough, (wearing headphones while auditory stimuli come from loudspeakers) and room simulation (externalization via headphones). We quantified reaction time (RT) and accuracy (choosing the correct direction to dodge) from the head movement. We hypothesized that the weight of the headset will slow RT, and that externalization of the auditory stimuli will make it more usable when no visual cues are provided. Interestingly, both hypotheses were refuted. In silent conditions, RT was faster with headphones compared to loudspeakers, but this difference disappeared when auditory stimuli were introduced. Participants used congruent auditory stimuli to improve accuracy but disregarded incongruent auditory stimuli across all apparatuses except for room simulation. In conclusion, this study confirmed that healthy young adults can use congruent auditory stimuli to enhance accuracy and disregard incongruent auditory stimuli such that accuracy is not harmed. RT was either faster or the same with headphones compared to loudspeakers. Notably, this specific room simulation did not enhance performance.

Imperceptible noisy galvanic vestibular stimulation (nGVS) improves standing balance due to the presence of stochastic resonance (SR). There is, however, a lack of consensus regarding the optimal levels and type of noise used to elicit SR like dynamics. We aimed to confirm the presence of SR behavior in the vestibular system of young healthy adults by examining postural responses to increasing amplitudes of white and pink noise stimulation scaled to individual cutaneous perceptual threshold. Forty (40) healthy young participants (19 males, 25.1 ± 5.6 years) were randomly divided into a group that received nGVS with white (WHITE group) or pink noise (PINK group). Participants performed a cutaneous perceptual threshold detection task followed by 8 trials of quiet standing and eyes closure (60s) with nGVS applied during the last 30s. Balance stabilization was quantified in the ratio of the stimulus versus pre-stimulus Centre of Pressure (CoP) 90% ellipse area, Root Mean Square (RMS) and mean velocity. Cutaneous perceptual threshold was similar across groups. Group analysis confirmed that the mean CoP velocity increased across nGVS intensities, particularly for the PINK group while the other two variables remained unchanged. Single subject analysis indicated that 55% of WHITE and 30% of PINK group participants showed an SR-like response judged by three experts. Results are puzzling with respect to the presence of SR-like response dynamics in young healthy adults and highlight the need for further research using individual calibrated stimulus intensities. White noise seems more effective than pink noise in revealing an SR-like response to nGVS.

Current clinical assessment tools don't fully capture the genuine neural deficits experienced by chronic stroke survivors and, consequently, they don't fully explain motor function throughout everyday life. Towards addressing this problem, here we aimed to characterise post-stroke alterations in upper-limb control from a novel perspective to the muscle synergy by applying, for the first time, a computational approach that quantifies diverse types of functional muscle interactions (i.e. functionally-similar (redundant), -complementary (synergistic) and -independent (unique)). From single-trials of a simple forward pointing movement, we extracted networks of functionally diverse muscle interactions from chronic stroke survivors and unimpaired controls, identifying shared and group-specific modules across each interaction type (i.e. redundant, synergistic and unique). Reconciling previous studies, we found evidence for both the concurrent preservation of healthy functional modules post-stroke and muscle network structure alterations underpinned by systemic muscle interaction re-weighting and functional reorganisation across all interaction types. Cluster analysis of stroke survivors revealed two distinct patient subgroups from each interaction type that all distinguished less impaired individuals who were able to adopt novel motor patterns different to unimpaired controls from more severely impaired individuals who did not. Our work here provides a nuanced account of post-stroke functional impairment and, in doing so, paves new avenues towards progressing the clinical use case of muscle synergy analysis.

Mind wandering can cause workers to overlook safety hazards and delay making accurate operational decisions, ultimately raising the potential for accidents. However, there is relatively little research on the physiological characteristics of drilling workers during mind wandering. The aim of this investigation was to tackle the constraints of previous studies and to establish a more comprehensive theoretical framework and practical guidance for safety management. To this end, the phenomenon of workload on mind wandering among drillers during the drilling process was investigated in depth. It focused on drilling site workers, using SART paradigm tasks and EEG devices to track cognitive states under various loads, exploring how they affect mind wandering and EEG mechanisms. Fifty workers participated, observing drilling images to judge accidents. Results showed workload influenced cognitive processes such as mind wandering occurrence, reaction time, accuracy, and brain connectivity. High workload increased reaction time, decreased accuracy, raised mind wandering frequency, altered theta, beta, and gamma waves, and reduced cerebral synchronisation and engagement. Workload affected employees' mind wandering, sensations, focus, and work status, with a positive correlation between workload and mind wandering, potentially harming work performance and safety. Analyzing EEG data helps identify mind wandering and develop intervention measures. In depth research on these features not only helps identify employee mind wandering, but also promotes the development of more precise and personalized intervention measures.

The current work aimed to understand the behavioral manifestations that result from disruptions to the selective facilitation of task-relevant sensory information at early cortical processing stages in those with a history of concussion. A total of 40 participants were recruited to participate in this study, with 25 in the concussion history group (Hx) and 15 in the control group (No-Hx). Somatosensory-evoked potentials (SEPs) were elicited via median nerve stimulation while subjects performed a task that manipulated their focus of attention toward or away from proprioceptive cues. Participants also completed an implicit motor sequence learning task relying solely on proprioceptive cues, as well as a visual attentional blink (AB) task to understand the effect of concussion on rapid shifts in attention. The Hx SEP data replicated past work showing an absence of relevancy-based facilitation at early cortical processing stages (N20-P27) that emerged at later processing stages. Our Hx showed evidence of relevancy-based facilitation at either the P50-N70 or the N70-P100. Performance on the learning task was not significantly different between the Hx and No-Hx. Performance on the AB task revealed greater AB magnitude in the Hx compared to the No-Hx. Collectively, these results suggest a compensatory strategy in the Hx that enables them to learn to the same degree as controls. However, when the attentional system is taxed with high temporal demands there are decrements in performance. These results are of particular importance given that these individuals are at an increased risk of sustaining subsequent concussions, and musculoskeletal injuries.

In recent years, the influence of dietary-related factors on neurodegenerative diseases has received considerable attention in the academic community, notably involving the food additive sodium nitrite (NaNO₂) and intermittent fasting behavior. However, the effects of NaNO₂ and intermittent fasting on spatial learning and memory have not been thoroughly investigated. This study conducted a controlled experiment to explore the impact of NaNO₂ and intermittent fasting on the hyperphosphorylation of hippocampal neurofilament (NF) and tau proteins, as well as spatial learning and memory in rats. Through Morris water maze experiments, the spatial learning and memory abilities of rats were assessed, while immunoblotting and immunohistochemistry techniques were employed to evaluate the phosphorylation levels and distribution of NF and tau proteins in the rat hippocampus. NaNO₂ was found to induce hyperphosphorylation of hippocampal NF and tau proteins at the Ser396/404 sites, which was accompanied by a decline in spatial learning and memory abilities. Conversely, intermittent fasting ameliorated the NaNO₂-induced hyperphosphorylation of hippocampal neurofilaments and the decline in learning and memory abilities, with no discernible effect on hippocampal tau protein hyperphosphorylation.

Exogenous spatial attention attenuates audiovisual integration (AVI). Previous studies on the effects of exogenous spatial attention on AVI have focused on the inhibition of return (IOR) effect induced by visual cues and the facilitation effect induced by auditory cues, but the differences between the effects of exogenous spatial attention (induced by visual and auditory cues) on AVI remain unclear. The present study used the exogenous spatial cue-target paradigm and manipulated cue stimulus modality (visual cue, auditory cue) in two experiments (Experiment 1: facilitation effect; Experiment 2: IOR effect) to examine the effects of exogenous spatial attention (evoked by cues in different modalities) on AVI. The results of Experiment 1 showed that the AVI effect at valid cue locations was significantly lower than that at invalid cue locations in both visual and auditory cue conditions, suggesting that the exogenous spatial facilitation effect evoked by both visual and auditory cues attenuated AVI. Further analysis showed that the facilitation effect induced by visual cues attenuated AVI to a greater extent than that induced by auditory cues. In Experiment 2, the AVI effect was significantly lower at valid cue locations than at invalid cue locations in the visual cue condition, whereas there was no significant difference in AVI effect between valid and invalid cue locations in the auditory cue condition, suggesting that the exogenous spatial IOR effect evoked by visual cues attenuated AVI, while the IOR effect evoked by auditory cues had no significant effect on AVI. Taken together, these results may suggest that exogenous spatial attention induced by visual cues has a greater effect on AVI than that induced by auditory cues.

This study investigated how the judgment of proximal joint position can be affected by touch alone, focused attention on the distal body part, or touch spatial localization. Participants completed a two-arm elbow joint position-matching task, in which they indicated the location of one forearm by the placement of the other. In four test conditions, matching was performed during (1) detection of touch (tactile stimulation of index finger pads), (2) spatial localization of fingers (attention focused on the position of index finger pads), (3) spatial localization of touch on fingers (attention focused on tactile stimulation of index finger pads), and (4) detection of touch but localization of fingers (tactile stimulation of index finger pads, but attention focusing on the spatial position of the pads). In the first experiment (n = 23), the sensitivity of muscle spindle receptors in both reference and indicator arms was reduced and equalized by both-slack conditioning. In the second experiment (n = 20), the illusion of excessive elbow flexion in the reference arm and excessive extension in the indicator arm was generated through extension-flexion conditioning. In the first experiment, the accuracy and precision of matching were unaffected in any test condition. In the second experiment, participants made amplified undershooting errors under attention-focused conditions. In conclusion, focused attention on the location of a distal body part and touch affects both the spatial localization of the limb and tactile remapping only when the perceived forearm position is misinterpreted due to imbalanced proprioceptive input from antagonistic arm muscles.

Peripersonal space (PPS), the space immediately surrounding one's body, contributes to interactions with the external environment. Previous studies have demonstrated that PPS expands during whole-body self-motion. Furthermore, motor and proprioceptive information contributes to this phenomenon. However, no study has disentangled the role of motor commands. Therefore, this study investigated the role of motor commands via a bike pedaling situation in a virtual reality environment. We compared three self-motion conditions: active condition where participants actively pedaled at a constant speed, passive condition where they were forced to pedal by the pedaling (exercise) device, and no-pedaling condition where they did not pedal at all. Participants observed large-field optic flow that simulated forward self-motion in all the conditions. For PPS measurements, we asked participants to quickly respond to the tactile stimulus on their chests when they observed an approaching visual probe. The PPS range was defined as the maximum distance at which the visual probe facilitated tactile detection (visual-facilitation effect). Results showed that the visual-facilitation effects were larger in the active pedaling condition than in the no-pedaling condition. Furthermore, the effects were attenuated as the probe distances from the body increased. These results suggest that motor command information can strongly contribute to PPS expansion.

Heroin addiction is one of the neuropsychiatric burdens that affects many genetic and epigenetic systems. While it is known that heroin may change the expressions of some genes in the brain during dependence, there is no detailed study related to which gene are mostly affected. Therefore, in the current study, we aimed to determine alterations in the miRNA profiles of rats' brains for providing a detailed analysis of molecular mechanisms in heroin addiction-related toxicology. Next generation global miRNA sequencing was used to predict potential miRNAs in prefrontal cortex (PC), hippocampus, ventral tegmental area (VTA), striatum, and Nucleus accumbens (NA) of rats that exposed to heroin by intravenous injections. The total daily dose was started with 2 mg/kg and ended with 10 mg/kg on the 10^th day. In the striatum, miR-18a, miR-17-5p, miR-20a-5p, miR-106a, miR-301a-3p, miR872-5p, miR-15a-5p, miR-500-3p, and miR-339-5p expressions were upregulated by nearly 2-to-4 times with heroin. The expressions of hippocampal miR-153-3p, miR-130a-3p, miR-204-5p, miR-15b-5p, and miR-137-3p and the expressions of miR-872, miR-183-5p, miR-20a-5p, miR-325-5p, miR-379-5p, and miR-340-5p in the VTA were 2-times higher in the heroin-addicted rats. While there was nearly 2-times increase in the miR-129-1-3p and miR-3068-3p expressions in the NA, no change was noted in the PC due to heroin. The only heroin-dependent downregulation was observed in the expressions of striatal miR-450b-3p and miR-103-1-5p of VTA. These results suggested that heroin addiction might give harm to brain by altering cytokine balance and increasing neuroinflammation and apoptosis. In addition, neurons also try to compensate these abnormalities by enhancing neurogenesis and angiogenesis through several miRNAs in the different brain regions. In conclusion, the present study may provide a more integrated view of the molecular mechanism and a potential biomarker that will aid in clinical diagnosis and treatment of heroin-dependence.