Frontiers in Integrative Neuroscience最新文献

Background: Altered patterns of eye-movements during scene exploration, and atypical gaze preferences in social settings, have long been noted as features of the Autism phenotype. While these are typically attributed to differences in social engagement and interests (e.g., preferences for inanimate objects over face stimuli), there are also reports of differential saccade measures to non-social stimuli, raising the possibility that fundamental differences in visuo-sensorimotor processing may be at play. Here, we tested the plasticity of the eye-movement system using a classic saccade-adaptation paradigm to assess whether individuals with ASD make typical adjustments to their eye-movements in response to experimentally introduced errors. Saccade adaptation can be measured in infants as young as 10 months, raising the possibility that such measures could be useful as early neuro-markers of ASD risk.

Methods: Saccade amplitudes were measured while children and adults with ASD (N = 41) and age-matched typically developing (TD) individuals (N = 68) made rapid eye-movements to peripherally presented targets. During adaptation trials, the target was relocated from 20-degrees to 15-degrees from fixation once a saccade to the original target location was initiated, a manipulation that leads to systematic reduction in saccade amplitudes in typical observers.

Results: Neither children nor adults with ASD showed any differences relative to TD peers in their abilities to appropriately adapt saccades in the face of persistently introduced errors.

Conclusion: Of the three studies to date of saccade adaptation in ASD, none have shown deficits in saccade adaptation that are sufficient to generalize to the whole or a subgroup of the ASD population. Unlike prior studies, we found no evidence for a slower adaptation rate during the early adaptation phase, and no of evidence greater variance of saccade amplitudes in ASD. In post hoc analysis, there was evidence for larger primary saccades to non-adapted targets, a finding requiring replication in future work.

Introduction: Occupational workers are increasingly aware of the risk of noise overexposure to the auditory system but lack awareness about potential risks to the vestibular system. The purpose of this study was to investigate changes in vestibular end organ function in a known at-risk noise-exposed population, firefighters compared to age- and sex-matched controls using electrophysiologic measures of cervical vestibular evoked myogenic potentials (cVEMP).

Methods: A cross-sectional observational study compared cVEMP response characteristics in 38 noise-exposed firefighters. Firefighters were grouped by years of exposure in the fire service. The cVEMP responses were compared within firefighter groups and between firefighters and age- and sex-matched controls. Dependent variables included the response characteristics of amplitude, latency and threshold.

Results: cVEMP response amplitudes were significantly decreased in firefighters compared to their age- and sex-matched controls. Threshold of the cVEMP responses were significantly higher in firefighters compared to controls and firefighters had a higher incidence of absent cVEMP responses compared to controls. Response amplitudes decreased with increasing years in the fire-service at an increased rate compared to their age- and sex-matched controls. Latency of the cVEMP response was not significantly different in firefighters compared to controls. These findings are consistent with both animal and human studies suggesting noise-induced changes in the sacculocollic pathway.

Discussion: In the absence of any reported vestibular symptoms or auditory indicators of noise-induced hearing loss, these early effects on the vestibular system point to a potential hidden vestibular loss.

Cerebral metabolites are associated with different physiological and pathological processes in brain tissue. Among them, the concentrations of N-acetylaspartate (NAA) and choline-containing compounds (Cho) in the thalamic region are recognized and analyzed as important predictive markers of brain impairment. The relationship among hypertension, modulation of brain metabolite levels and cerebral diseases is of recent investigation, leaving many unanswered questions regarding the origin and consequences of the metabolic damage caused in grey and white matter during hypertension. Here we provide evidence for the influence of hypertension on NAA and Cho ratios in hypertensive rat thalamus and how the use of natural occurring compounds ameliorates the balance of thalamic metabolites.

Introduction: Cervical vestibular evoked myogenic potentials (cVEMPs) provide an objective measure of the integrity of the sacculo-collic pathway leading to their widespread use as a clinical tool in the diagnostic vestibular test battery. Though the application of cVEMPs in preclinical models to assess vestibular function, as performed in relevant clinical populations, remains limited. The present study aimed to establish a rodent model of cVEMP with standardized methods and protocols, examine the neural basis of the responses, and characterize and validate important features for interpretation and assessment of vestibular function.

Methods: We compared air-conducted sound (ACS)-evoked VEMPs from the sternocleidomastoid muscles in naïve Brown Norway rats. A custom setup facilitated repeatable and reliable measurements which were carried out at multiple intensities with ACS between 1 and 16 kHz and over 7 days. The myogenic potentials were identified by the presence of a positive (P1)-negative (N1) waveform at 3-5 ms from the stimulus onset. Threshold, amplitude, and latency were compared with intensity- and frequency-matched responses within and between animals.

Results: cVEMP responses were repeatedly evoked with stimulus intensities between 50-100 dB SPL with excellent test-retest reliability and across multiple measurements over 7 days for all frequencies tested. Suprathreshold, cVEMP responses at 90 dB SPL for 6-10 kHz stimuli demonstrated significantly larger amplitudes (p < 0.01) and shorter latencies (p < 0.001) compared to cVEMP responses for 1-4 kHz stimuli. Latency of cVEMP showed sex-dependent variability, but no significant differences in threshold or amplitude between males and females was observed.

Discussion: The results provide a replicable and reliable setup, test protocol, and comprehensive characterization of cVEMP responses in a preclinical model which can be used in future studies to elucidate pathophysiological characteristics of vestibular dysfunctions or test efficacy of therapeutics.

Introduction: Visual disturbance is common symptom in Parkinson's disease (PD), and defective pupil light reflex (PLR) is an anticipated contributing factor that may be associated to the presence of autonomic dysfunction, which is a common non-motor feature of PD. Studies investigating the intercorrelation between PLR and dysautonomia in PD are limited.

Methods: The aim of this study was to investigate differences of PLR parameters, measured by eye-tracker, between patients with PD, with and without signs of dysautonomia, and healthy controls (HC). In total, 43 HC and 50 patients with PD were recruited and PLR parameters were measured with Tobii Pro Spectrum, during a long (1,000 ms) and a short (100 ms) light stimulus. Presence of orthostatic hypotension (OH) was used as proxy marker of dysautonomia. Linear mixed-effects model and non-parametric comparative statistics were applied to investigate differences among groups.

Results: Peak constriction velocity was slower in PD compared with HC, after adjustment for age and sex in the mixed model, and the difference was greater in the subgroup of PD with OH (unadjusted). Dilation amplitude and velocity were also gradually slower in HC vs. PD without OH vs. PD with OH (unadjusted for confounders). In the mixed model, age was significant predictor of dilation response.

Discussion: Our results support previous observations on defective PLR in PD, evaluated with eye-tracker, and show a possible association with autonomic dysfunction. Further studies with more patients and rigorous evaluation of autonomic dysfunction are needed to validate these findings.

Many techniques have attempted to provide physical support to ease the execution of a typing task by individuals with developmental disabilities (DD). These techniques have been controversial due to concerns that the support provider's touch can influence the typed content. The most common interpretation of assisted typing as an ideomotor phenomenon has been qualified recently by studies showing that users with DD make identifiable contributions to the process. This paper suggests a neurophysiological pathway by which touch could lower the cognitive load of seated typing by people with DD. The required sensorimotor processes (stabilizing posture and planning and executing manual reaching movements) and cognitive operations (generating and transcribing linguistic material) place concurrent demands on cognitive resources, particularly executive function (EF). A range of developmental disabilities are characterized by deficits in sensorimotor and EF capacity. As light touch has been shown to facilitate postural coordination, it is proposed that a facilitator's touch could assist the seated typist with sensorimotor and EF deficits by reducing their sensorimotor workload and thereby freeing up shared cognitive resources for the linguistic elements of the task. This is the first theoretical framework for understanding how a facilitator's touch may assist individuals with DD to contribute linguistic content during touch-assisted typing.

Background: Alcohol and tobacco are known teratogens. Historically, more severe prenatal alcohol exposure (PAE) and prenatal tobacco exposure (PTE) have been examined as the principal predictor of neurodevelopmental alterations, with little incorporation of lower doses or ecological contextual factors that can also impact neurodevelopment, such as socioeconomic resources (SER) or adverse childhood experiences (ACEs). Here, a novel analytical approach informed by a socio-ecological perspective was used to examine the associations between SER, PAE and/or PTE, and ACEs, and their effects on neurodevelopment.

Methods: N = 313 mother-child dyads were recruited from a prospective birth cohort with maternal report of PAE and PTE, and cross-sectional structural brain neuroimaging of child acquired via 3T scanner at ages 8-11 years. In utero SER was measured by maternal education, household income, and home utility availability. The child's ACEs were measured by self-report assisted by the researcher. PAE was grouped into early exposure (<12 weeks), continued exposure (>=12 weeks), and no exposure controls. PTE was grouped into exposed and non-exposed controls.

Results: Greater access to SER during pregnancy was associated with fewer ACEs (maternal education: β = -0.293,p = 0.01; phone access: β = -0.968,p = 0.05). PTE partially mediated the association between SER and ACEs, where greater SER reduced the likelihood of PTE, which was positively associated with ACEs (β = 1.110,p = 0.01). SER was associated with alterations in superior frontal (β = -1336.036, q = 0.046), lateral orbitofrontal (β = -513.865, q = 0.046), caudal anterior cingulate volumes (β = -222.982, q = 0.046), with access to phone negatively associated with all three brain volumes. Access to water was positively associated with superior frontal volume (β=1569.527, q = 0.013). PTE was associated with smaller volumes of lateral orbitofrontal (β = -331.000, q = 0.033) and nucleus accumbens regions (β = -34.800, q = 0.033).

Conclusion: Research on neurodevelopment following community-levels of PAE and PTE should more regularly consider the ecological context to accelerate understanding of teratogenic outcomes. Further research is needed to replicate this novel conceptual approach with varying PAE and PTE patterns, to disentangle the interplay between dose, community-level and individual-level risk factors on neurodevelopment.

Introduction: The vestibular system integrates signals related to vision, head position, gravity, motion, and body position to provide stability during motion through the environment. Disruption in any of these systems can reduce agility and lead to changes in ability to safely navigate one's environment. Causes of vestibular decline are diverse; however, excessive noise exposure can lead to otolith organ dysfunction. Specifically, 120 decibel (dB) sound pressure level (SPL) 1.5 kHz-centered 3-octave band noise (1.5 kHz 3OBN) causes peripheral vestibular dysfunction in rats, measured by vestibular short-latency evoked potential (VsEP) and reduced calretinin-immunolabeling of calyx-only afferent terminals in the striolar region of the saccule. The present study examined the functional impact of this noise exposure condition, examining changes in motor performance after noise exposure with a balance beam crossing task.

Methods: Balance beam crossing time in rats was assessed for 19 weeks before and 5 weeks after noise exposure. Balance beam crossings were scored to assess proficiency in the task. When animals were proficient, they received a single exposure to 120 dB SPL 3-octave band noise.

Results: During the initial training phase slower crossing times and higher scores, including multiple failures were observed. This was followed by a period of significant improvement leading to proficiency, characterized by fast and stable crossing times and consistently low scores. After noise exposure, crossing times were significantly elevated from baseline for 4-weeks. A total of 5 weeks after noise exposure, crossing times improved, and though still trending higher than baseline, they were no longer significantly different from baseline.

Discussion: These findings show that the noise-induced peripheral vestibular changes we previously observed at cellular and electro-physiological levels also have an impact at a functional level. It has been previously shown that imbalance is associated with slower walking speed in older adults and aged rats. These findings in noise-exposed rats may have implications for people who experience noisy environments and for seniors with a history of noise exposure who also experience balance disorders and may be at increased fall risk.