Experimental Brain Research最新文献

Aging leads to various changes in nervous system functions. Older humans and animals exhibit altered movement patterns and experience alterations in memory and motor functions. Rodent models, particularly aged C57BL/6 mice, have been instrumental in studying behavioral and neurophysiological changes associated with aging. This study aimed to characterize age-related cognitive and motor decline and examine its association with molecular changes in a physiologically aged murine model. For this purpose, female C57BL/6Cenp mice aged 2, 20, and 26 months were used. Several behavioral tests were conducted to evaluate motor and cognitive functions. Additionally, gene expression levels were analyzed in prefrontal cortex and hippocampus samples. Twenty-month-old mice exhibited reduced muscle strength, altered gait patterns, impaired balance on the rotarod test, and deficits in spatial reference memory as assessed by the Barnes maze. Motor function further deteriorated in senescent mice (26-month-old), accompanied by spatial memory impairment as assessed using forced Y-maze test. Moreover, significant changes were observed in the expression of genes associated with synaptic plasticity (ARC, CREB1), neuronal activity (FOS), myelination (OLIG1, MAL), and oxidative stress (CYBA, CYBB, NCF1). These findings confirm that aging is a complex phenomenon marked by progressive cognitive and motor impairments, driven by molecular changes in brain regions involved in critical functions such as motor processes and cognition.

The vestibulospinal and reticulospinal tracts play a crucial role in controlling lumbar erector spinae (LES). Electrical vestibular stimulation (EVS) can be used to investigate the contribution of the vestibular system in the control of a muscle during a motor task. A recent study observed a minimal contribution of the corticospinal projection to LES in a voluntary spine extension. We thus hypothesised a greater involvement of alternative pathways originating in the brainstem such as vestibulo- and reticulospinal tracts in the control of LES for this task. This study investigates the impact of EVS on the activation of LES during postural and voluntary tasks. Fifteen participants performed two motor tasks: a bilateral shoulder flexion (postural task) and a lumbar spine extension (voluntary task) during a simple precued reaction time (RT) paradigm. During the RT tasks, EVS was applied at three different timings (early, middle and late) within a pre-defined time window. Outcomes were (1) LES onset latencies elicited by the motor tasks and conditioned by EVS and (2) the central processing duration (CPD). EVS significantly reduced the onset latency of LES activation in both postural and voluntary tasks. The CPD was shorter for the postural compared to the voluntary task for the early and middle conditions. EVS shortens LES onset, suggesting a contribution of brainstem networks/tracts in both tasks. The shorter CPD for the postural task at early and middle timings compared to the voluntary task suggests an earlier contribution of the brainstem networks/tracts during the postural task. Further research is needed to elucidate the mechanisms and validate this paradigm.im.

Children born very preterm (VPT, ≥ 28 to < 32 gestational weeks) and extremely preterm (EPT, < 28 weeks) are at higher risk for autistic traits and biological motion (BM) processing deficits. Thus, we aimed to examine links between autistic traits and a condensed BM interpretation assessment, as well as potential group differences in performance in 12-year-old children born preterm and full-term. Four short BM stimuli (point-light-walkers) in two noise levels were presented to 25 EPT, 53 VPT and 48 full-term 12-year-old children. Accuracy in BM interpretation was compared across groups and analyzed with parental ratings on the Social Responsiveness Scale 2, adjusting for neonatal characteristics and intelligence. Interactions between preterm status and BM interpretation accuracy with autistic traits were explored. Results showed that the children born EPT had poorer accuracy interpreting BM than the other groups, and children born VPT showed poorer accuracy BM interpretation in high noise compared with the full-term group. BM interpretation accuracy was linked to autistic traits in the EPT and VPT groups. Children born preterm with the poorest BM interpretation accuracy also exhibited the most autistic traits. We concluded that the condensed assessment found prematurity-related deficits in BM interpretation. Performance was strongly linked to autistic traits in the preterm groups, highlighting the relevance of BM interpretation for social reciprocity in children born VPT and EPT.

Healthy adults (OA) achieve rapid isometric force production with a brief, high amplitude burst of neural excitation. In some people with Parkinson's disease (PwPD), transient reductions in neural excitation (motor segmentation) reduce rates of force development (RFD) and prolong contractions. Segmentation has strong relationships with time and rate-based measures of slowing in rapid contractions and is reliably measured from the second derivative of force (F"(t)). We sought more information about how segmentation affects neuromuscular control in PwPD. Aim 1 was to determine the prevalence of PwPD with segmentation (PD_Seg). Aim 2 was to determine how force performance differs in PD_Seg, PwPD without segmentation (PD_NoSeg), and OA. Aim 3 was to quantify force segment durations. Fifty-seven PwPD ON medication and 22 OA performed rapid isometric finger abduction contractions to 20-60% of maximal voluntary contraction force. The median number of force segments to 90% of peak force were measured from F"(t) zero crossings. Additional outcomes included median times to peak force (tPF) and peak RFD (tRFD), and peak RFD (RFDpk). 68% of PwPD had segmentation (median segments ≥ 2, 95% CI [0.55 0.80]). PD_Seg had slower tPF, tRFD and RFDpk than PD_NoSeg and OA (all p ≤ 0.012, 0.38 ≤ r ≤ 0.85). PD_NoSeg and OA did not have statistically different tPF, tRFD, or RFDpk (p > 0.05). PD_Seg had consistent segment durations (coefficient of variation ≤ 25.5%) and shorter first segment durations compared to PD_NoSeg and OA (p < 0.001, r ≥ 0.68), indicating PD_Seg had reduced neuromuscular excitation prior to peak force. Segmentation identifies specific pathophysiology in neuromuscular control that exacerbates slowing in isometric force production.

This is a randomized crossover study design. We examined the acute effects of prolonged social media use (SMU) vs. computerized Modified Stroop Task (MST) on electroencephalogram (EEG) spectral power and physical performance in taekwondo (TKD) athletes. Fifteen athletes underwent cognitive manipulations (SMU, MST, documentary [DOC]), followed by mental tiredness checks (Visual Analogue Scale [VAS]), EEG measurements, an intermittent TKD task, and psychobiological variables (heart rate [HR], rating perceived exertion [RPE]). Only MST significantly increased the VAS (p < 0.05). Theta power decreased in the parietal cortex after cognitive manipulations across conditions (p < 0.001). MST presented a time effect for theta, alpha 1, and alpha 2 in parietal cortex during the task at 15 min (ps < 0.004), diminishing over time. Physical performance declined throughout rounds (p < 0.001), more under MST vs. DOC (p = 0.03). RPE increased (p < 0.001); no significant difference in HR was found (ps > 0.07). High cognitive demand tasks may impair the performance of TKD athletes.

Interhemispheric inhibition (IHI) acts between hemispheres to decrease motor cortical excitability. IHI changes during movement preparation, but it is unknown whether altering IHI, independent of other factors, alters movement initiation. For the index finger abductor muscle (first dorsal interosseous; FDI), IHI is weaker during contralateral index abduction than adduction. Thus, this study aimed to modulate IHI through contralateral contraction and measure resultant changes in reaction time. Fifteen healthy participants (age 19-39 years) completed a reaction-time task requiring brief left index finger abduction. Prior to reactions, participants started either a sustained isometric abduction or adduction contraction of the right index finger. Single- or paired-pulse transcranial magnetic stimulation (TMS) elicited motor evoked potentials (MEPs) from left FDI in the late pre-movement phase. For each contralateral contraction direction, unconditioned and conditioned MEPs (preceded by suprathreshold TMS over the other hemisphere at 10 or 40 ms) were recorded. Conditioned MEPs, expressed relative to unconditioned MEPs, provided measures of short-interval IHI (SIHI) and long-interval IHI (LIHI). Left index finger reaction time was also measured. Linear mixed models showed that reaction time was 9 ± 9 ms (6%) slower during right adduction than abduction (F_1,1875 = 30.7, p < 0.001). Unconditioned MEPs in left FDI were 1.1 ± 2.0 mV (37%) smaller (F_1,270 = 8.82, p = 0.003) and SIHI 11 ± 16% stronger during right adduction (F_1,279 = 15.15, p < 0.001). However, LIHI was not different between right contraction conditions (F_1,272 = 0.410, p = 0.522). These results suggest that IHI can alter reaction time by influencing corticospinal excitability. Stronger SIHI during right adduction likely delayed pre-movement increases in corticospinal excitability, slowing reaction time.

Bupivacaine is a commonly used local anesthetic in both human and equine medicine. This study aimed to explore the molecular mechanism of bupivacaine-induced postoperative cognitive dysfunction (POCD). Bioinformatics analysis identified YES proto-oncogene 1 (YES1) as a key player. A POCD mouse model was developed using bupivacaine and surgery, followed by assessment of cognitive function and DNA damage. SH-SY5Y cells were exposed to bupivacaine, and DNA damage was analyzed. Verteporfin, a Yes-associated protein 1 (YAP1) inhibitor, was used in both mice and cells to study its effects. Bupivacaine increased escape latency and decreased the number of platform crossings in the Morris water maze test, and reduced total distance traveled in the open field test and discrimination index in the novel object recognition test, which was associated with the suppression of YES1 expression in the hippocampal tissue of mice. YES1 overexpression alleviated POCD and neuronal DNA damage induced by bupivacaine in mice by promoting YAP1 phosphorylation. Treatment with verteporfin reversed the alleviating effects of YES1 overexpression on neuronal DNA damage and exacerbated POCD in mice. In conclusion, bupivacaine induces POCD by suppressing YES1 expression and YAP1 phosphorylation, leading to DNA damage.

Gulf War Illness (GWI) affects approximately 30% of veterans who served in the 1991 Persian Gulf War and is characterized by chronic pain and fatigue, as well as cognitive, mood, gastrointestinal, and respiratory symptoms. Animal research has suggested that GWI is caused by a combination of neurotoxicants such as nerve gas, anti-nerve agent pills, and pesticides, though a definitive pathophysiological model has not been established. In this human observational study, 20 veterans with GWI and 20 healthy Gulf War veterans (HV) underwent whole-brain magnetic resonance spectroscopy to non-invasively measure several metabolites associated with neuroinflammation. Veterans also completed an arterial spin labeling scan to assess cerebral perfusion. Compared to HV, veterans with GWI demonstrated widespread decreases in brain choline, N-acetylaspartate, and creatine, and regional elevations in lactate and brain temperature. No group difference was observed in cerebral perfusion. Exploratory analyses revealed brain metabolites were associated with self-reported neurotoxicant exposures in theater. These findings support a role of cholinergic alterations and neuroinflammatory processes in GWI. Trial registration: The study was registered in ClinicalTrials.gov, ID NCT04638998. Registered November 16, 2020, https://clinicaltrials.gov/study/NCT04638998 .

The control of reaches to targets that vary in distance involves a combination of anticipatory planning and feedback-based adjustments. However, it is not known if their contributions to the control of reach extent change with repetitive practice. This study investigated the effect of three days of practice on the control of reach extent. Right-hand dominant participants reached with either the non-dominant left arm or dominant right arm to six targets presented in two directions and three distances in a virtual environment. The effect of practice on planning and feedback-based adjustments to control reach extent was examined by determining how well peak acceleration and time to peak velocity predicted the eventual distance moved, respectively. Both arm groups demonstrated improvements in reach performance (decreased endpoint error and movement time). The Left Arm group demonstrated an increased use of anticipatory planning and feedback-based adjustments to control reach extent with practice while the Right Arm group did not show a change. Changes in the control of reach extent seen in the Left Arm group may reflect experience-dependent creation of a more robust internal model of the arm and/or increased weighting of control mechanisms from the dominant left-brain hemisphere. The potential to modify the use of anticipatory planning and feedback-based adjustments to control reach movements may be relevant for rehabilitation approaches in clinical populations such as stroke who have altered control of reach extent.

Anticipatory postural adjustments (APAs) are generally understood to be cortically driven, however there is some evidence to suggest subcortical regulation and contribution. We tested the hypothesis that subcortical pathways, if contributing, would be evidenced in increased late portions of the motor evoked potential (MEP) elicited by transcranial magnetic stimulation during different time intervals before and during the APA. Recordings from both the tibialis anterior and soleus muscles showed little evidence for this throughout the course of the APA, pointing instead to a generally cortical source for the APA. Despite this, the brainstem did not appear inactive, with MEPs elicited during voluntary contraction of the soleus being significantly smaller than those elicited prior to executing an APA- specifically during the later portion of the MEP, thought reflective of subcortical contribution. Further work to isolate specific brainstem upregulation and contribution is needed.