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Background: Noise-induced cochlear synaptopathy has recently emerged as a focus in hearing research. Purpose: This study aimed to examine the impact of repeated noise exposure on the quantification and mRNA expression levels of cochlear synapses. Methods: Measurements were conducted at baseline, 1 day, and 14 days post-exposure to 88 or 97 dB SPL noise (2 h/day for 7 days, frequency range 2-20 kHz). Auditory brainstem responses (ABRs), immunofluorescence and quantitative real-time PCR (qRT-PCR) were used to examine the results. Results: 1. Exposure to 88 dB SPL caused minimal changes in ABRs, ribbon morphology and medial olivocochlear (MOC) efferent synapses; elevation of synaptophysin(SYP) and α9α10 nAchR mRNA levels were observed. 2. Exposure to 97 dB SPL caused threshold shift and synaptopathy of ribbon and MOC; downregulation of α10nAchR, SYP and ctbp2 mRNA levels were observed. Conclusion: Noise-induced cochlear synaptic degeneration involves both afferent and efferent synaptopathy. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the cochlea, medial olivocochlear system, and brainstem function in autistic children using evoked otoacoustic emissions (OAEs) and a noninvasive contralateral suppression (CLS) test. In total, we included 21 autistic children with normal hearing (study group) and 11 healthy children (control group). Transient-evoked OAEs (TEOAEs) and CLS of TEOAE were evaluated in the left and right ears of all patients. In a silent room, spontaneous, transient, and dP ILO292 were evaluated. The mean age of the study and control group was 9.1 years (range: 6-13 and 6-12 years, respectively). For the study group, there was no statistically significant difference between the OAE and CLS values of the right ear (P >.05). However, for the left ears, OAE values were statistically significantly higher than the CLS values (P <.05). In the control group, the OAE values of both ears were statistically significantly higher than the CLS values (P <.05). In autistic children with normal hearing, the medial olivocochlear system functions more effectively in the right ear than the left ear. Asymmetry between the ears is likely responsible for the peripheral auditory lateralization and independence in auditory function between the left and right ears. [ABSTRACT FROM AUTHOR]

Purpose: The auditory brainstem response (ABR) can be elicited by broadband stimuli such as the click and chirp. Differences in the click- and chirp-evoked ABR have been extensively described using subjective analyses. The aim of the current research is to determine if subjectively observed differences between the click- and chirp-evoked ABR are also represented in objective signal-tonoise ratio (SNR) measurements obtained from these responses at different stimulus intensities and sweep counts. Method: ABRs were collected using click and chirp stimuli on nine adults with normal hearing sensitivity. Three SNR methods (split-sweep average--based SNR [SSA-SNR], F ratio--based single-point [Fsp], and multipoint [Fmp]) were used for the objective analysis of the waveforms at four stimulus intensities (20, 40, 60, and 80 dB nHL) and five sweep counts (100, 200, 300, 400, and 500 sweeps). Results: SSA-SNR measurements were statistically stronger for chirp- as compared to click-evoked ABRs. Additionally, chirp/click SSA-SNR, Fsp, and Fmp ratio measurements were consistently greater than 1. The advantage associated with the chirp was most noticeable at moderate stimulus intensities for all three measurements. Discussion: The advantages for the chirp observed here could have implications for threshold estimation and screening ABR tests. Furthermore, when stimulus intensity and sweep count were varied, general response trends suggest that the three SNR-based methods performed similarly to each other, as well as to traditionally used subjective measures, suggesting that these techniques have the potential to be used effectively in clinic. [ABSTRACT FROM AUTHOR]

Background: Migraine and insomnia are prevalent conditions that often co-occur, each exacerbating the other and substantially impacting the quality of life. The locus coeruleus (LC), a brainstem region responsible for norepinephrine synthesis, participates in pain modulation, sleep/wake cycles, and emotional regulation, rendering it a potential nexus in the comorbidity of migraine and insomnia. Disruptions in the LC-noradrenergic system have been hypothesized to contribute to the comorbidities of migraine and insomnia, although neuroimaging evidence in humans remains scarce. In this study, we aimed to investigate the intrinsic functional connectivity (FC) network of the LC in patients with comorbid migraine and subjective chronic insomnia and patients with migraine with no insomnia (MnI) using resting-state functional magnetic resonance imaging (rs-fMRI) and seed-based FC analyses. Methods: In this cross-sectional study, 30 patients with comorbid migraine and chronic insomnia (MI), 30 patients with MnI, and 30 healthy controls (HCs) were enrolled. Participants underwent neuropsychological testing and rs-fMRI. The LC-FC network was constructed using seed-based voxel-wise FC analysis. To identify group differences in LC-FC networks, voxel-wise covariance analysis was conducted with sex and age as covariates. Subsequently, a partial correlation analysis was conducted to probe the clinical relevance of aberrant LC-FC in patients with MI and MnI. Results: Except for the insomnia score, no other significant difference was detected in demographic characteristics and behavioral performance between the MI and MnI groups. Compared with HCs, patients with MI exhibited altered LC-FC in several brain regions, including the dorsomedial prefrontal cortex (DMPFC), anterior cerebellum, dorsolateral prefrontal cortex (DLPFC), thalamus, and parahippocampal gyrus (PHG). Lower FC between the LC and DLPFC was associated with greater insomnia severity, whereas higher FC between the LC and DMPFC was linked to longer migraine attack duration in the MI group. Conclusion: Our findings reveal the presence of aberrant LC-FC networks in patients with MI, providing neuroimaging evidence of the interplay between these conditions. The identified LC-FC alterations may serve as potential targets for therapeutic interventions and highlight the importance of considering the LC-noradrenergic system in the management of MI. [ABSTRACT FROM AUTHOR]

Introduction: Some electrophysiological changes can occur in the auditory system in response to noise exposure with or without any permanent auditory threshold shift. The purpose of this study was to identify and measure cochlear function after noise exposure in individuals with normal hearing according to standard audiometric thresholds. Material and methods: Pure tone audiometry (PTA) over the standard 0.250--8 kHz range and at 12 kHz, as well as distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) testing, were performed on 42 soldiers who had participated in combat. A control group of 40 participants underwent the same tests. Results: In the noise-exposed group, significantly poorer PTA thresholds were recorded at 12 kHz. DPOAE levels were significantly low only at 4 kHz. On ABR testing, both wave I and wave V demonstrated a significant decrease in amplitude and a significant increase in latency for the noise-exposed group. Conclusions: Our findings reveal that high levels of noise can not only damage outer hair cells but also cause changes at the level of the synapses (synaptopathy) which are not evident using standard PTA tests. However, electrophysiological methods can detect some changes in cochlear function. [ABSTRACT FROM AUTHOR]

This exploratory study examined whether central auditory tests show differences between people living with HIV (PLWH) treated with two predominant antiretroviral drug therapy (ART) regimens. Cross-sectional. 253 PLWH (mean age 39.8 years) from the Shanghai Public Health Clinical Centre, China. The Hearing in Noise Test speech reception threshold (SRT) assessed central auditory function and the Montreal Cognitive Assessment (MoCA) assessed cognition. The relationship between ART regimen and SRT was evaluated with multivariable linear regression incorporating age, HIV duration, and peripheral hearing ability. Multivariable logistic regression was used to ascertain if SRT and ART regimen predicted MoCA impairment. The two predominant ART regimens differed by one drug (zidovudine or tenofovir). Participants taking the zidovudine-containing regimen had poorer SRT performance (p=.012) independent of age and hearing thresholds. MoCA scores did not differ between drug regimens, but a negative relationship was found between SRT and MoCA impairment (p=.048). ART regimens differed in their association with central auditory test performance likely reflecting neurocognitive changes in PLWH taking the zidovudine-containing regimen. Central auditory test performance also marginally predicted cognitive impairment, supporting further assessment of central auditory tests to detect neurocognitive deficits in PLWH. [ABSTRACT FROM AUTHOR]

The underlying mechanisms of bright light therapy (BLT) in the prevention of individuals with subthreshold depression symptoms are yet to be elucidated. The goal of the study was to assess the correlation between midbrain monoamine-producing nuclei treatment-related functional connectivity (FC) changes and depressive symptom improvements in subthreshold depression. This double-blind, randomized, placebo-controlled clinical trial was conducted betweenMarch 2020 and June 2022. A total of 74 young adults with subthreshold depression were randomly assigned to receive 8-week BLT (N = 38) or placebo (N = 36). Depression severity was measured using the Hamilton Depression Rating Scale (HDRS). The participants underwent resting-state functional magnetic resonance imaging at baseline and after treatment. The dorsal raphe nucleus (DRN), ventral tegmental area (VTA), and habenula seed-based whole-brain FC were analyzed. A multivariate regression model examined whether baseline brain FC was associated with changes in scores on HDRS during BLT treatment. BLT group displayed significantly decreased HDRS scores frompre- to posttreatment compared to the placebo group. BLT increased the FC between the DRN and medial prefrontal cortex (mPFC) and between the left VTA and right superior frontal gyrus (SFG). Altered VTA--SFG connectivity was associated with HDRS changes in the BLT group.Moreover, the baseline FC between DRN and mPFC could predict HDRS changes in BLT. These results suggested that BLT improves depressive symptoms and increases midbrain monoamine-producing nuclei and frontal cortex connectivity in subthreshold depression, which raises the possibility that pretreatment FC of DRN--mPFC could be used as a biomarker for improved BLT treatment in depression. [ABSTRACT FROM AUTHOR]

Objective: It has recently been discussed whether hearing screening and hearing threshold assessment can accurately be completed using automated ASSR methods for children with auditory neuropathy spectrum disorder (ANSD). Possible causes for the claimed potential failures were investigated here. Design: The study is based on the analysis of stored ASSR raw data. Study sample: This study reviewed raw ASSR data from 274 patients with a total of 5809 individual recordings. Results: Cochlear microphonics (CM) were found in 18 of the 274 patient records. Four of these 18 were obtained from patients with ANSD. One patient with ANSD without click auditory brainstem responses up to 100 dBnHL demonstrated clear ASSR responses from 65 dBnHL upwards. Where click stimulation suggests an auditory nerve defect, narrow-band chirps were shown to evoke ASSR in certain patients. CMs are elicited by narrow-band chirps in the same way as by broadband stimuli. CM residuals as well as a presumed enlarged wave I with absent neural responses, always accompanied by CM, were found as possible causes of misinterpretation at high stimulus levels. A CM detector was created. Conclusions: The CM detector, indicating the presence of CM, will prevent misinterpretation of clinical ASSR results. [ABSTRACT FROM AUTHOR]

Background: Insomnia is a well-recognized clinical sleep disorder in the adult population. It has been established that acupuncture has a clinical effects in the treatment of insomnia; however, research on the underlying neural circuits involved in these effects is limited. Methods: The modified multiple platform method (MMPM) was used to establish a rat model of chronic sleep deprivation (CSD). Forty rats were randomly divided into a control (Con) group, (untreated) CSD group, electroacupuncture-treated CSD group (CSD + EA) and estazolam-treated CSD group (CSD + Estazolam group) with n = 10 per group. In the CSD + EA group, EA was delivered at Yintang and unilateral HT7 (left and right treated every other day) with continuous waves (2 Hz frequency) for 30 min/day over 7 consecutive days. In the CSD + Estazolam groups, estazolam was administered by oral gavage (0.1 mg/kg) for 7 consecutive days. The open field test (OFT) was used to observe behavioral changes. Immunofluorescence assays and enzyme-linked immunosorbent assay (ELISA) were used to observe the effects of EA on the ventral tegmental area (VTA)-nucleus accumbens (NAc) dopamine (DA) pathway. We also assessed the effects of EA on the expression of dopamine D1 receptor (D1R) and dopamine D2 receptor (D2R) in the NAc, which are the downstream targets of the VTA-NAc DA pathway. Results: After CSD was established by MMPM, rats exhibited increased autonomous activity and increased excitability of the VTA-NAc DA pathway, with increased VTA and NAc DA content, increased D1R expression and decreased D2R expression in the NAc. EA appeared to reduce the autonomous ability of CSD rats, leading to lower DA content in the VTA and NAc, reduced expression of D1R in the NAc and increased expression of D2R. Most importantly, EA produced effects similar to estazolam with respect to the general condition of rats with CSD and regulation of the VTA-NAc DA pathway. Conclusions: The therapeutic effect of EA in chronic insomnia may be mediated by reduced excitability of the VTA-NAc DA pathway, with lower DA content in the VTA and NAc, downregulated expression of D1R in the NAc and increased expression of D2R. [ABSTRACT FROM AUTHOR]

Background and Objective: It is documented that low protein and amino-acid dietary intake is related to poorer cognitive health and increased risk of dementia. Degradation of the neuromodulatory pathways, (comprising the cholinergic, dopaminergic, serotoninergic and noradrenergic systems) is observed in neurodegenerative diseases and impairs the proper biosynthesis of key neuromodulators from micro-nutrients and amino acids. How these micro-nutrients are linked to neuromodulatory pathways in healthy adults is less studied. The Locus Coeruleus–Noradrenergic System (LC-NA) is the earliest subcortical structure affected in Alzheimer's disease, showing marked neurodegeneration, but is also sensitive for age-related changes. The LC-NA system is critical for supporting attention and cognitive control, functions that are enhanced both by tyrosine administration and chronic tyrosine intake. The purpose of this study was to 1) investigate whether the dietary intake of tyrosine, the key precursor for noradrenaline (NA), is related to LC signal intensity 2) whether LC mediates the reported association between tyrosine intake and higher cognitive performance (measured with Trail Making Test–TMT), and 3) whether LC signal intensity relates to an objective measure of brain maintenance (BrainPAD). Methods: The analyses included 398 3T MRIs of healthy participants from the Berlin Aging Study II to investigate the relationship between LC signal intensity and habitual dietary tyrosine intake-daily average (HD-Tyr-IDA - measured with Food Frequency Questionnaire - FFQ). As a control procedure, the same analyses were repeated on other main seeds of the neuromodulators' subcortical system (Dorsal and Medial Raphe, Ventral Tegmental Area and Nucleus Basalis of Meynert). In the same way, the relationships between the five nuclei and BrainPAD were tested. Results: Results show that HD-Tyr-IDA is positively associated with LC signal intensity. Similarly, LC disproportionally relates to better brain maintenance (BrainPAD). Mediation analyses reveal that only LC, relative to the other nuclei tested, mediates the relationship between HD-Tyr-IDA I and performance in the TMT and between HD-Tyr-IDA and BrainPAD. Conclusions: These findings provide the first evidence linking tyrosine intake with LC-NA system signal intensity and its correlation with neuropsychological performance. This study strengthens the role of diet for maintaining brain and cognitive health and supports the noradrenergic theory of cognitive reserve. Within this framework, adequate tyrosine intake might increase the resilience of LC-NA system functioning, by preventing degeneration and supporting noradrenergic metabolism required for LC function and neuropsychological performance. [ABSTRACT FROM AUTHOR]

Background: To explore the altered functional connectivity (FC) of the nucleus tractus solitarii (NTS) in patients with chronic cough after lung surgery using resting‐state functional magnetic resonance imaging (rs‐fMRI), and the association between abnormal FC and clinical scale scores. Methods: A total of 22 patients with chronic cough after lung surgery and 22 healthy controls were included. Visual analog scale (VAS), Mandarin Chinese version of the Leicester Cough Questionnaire (LCQ‐MC), and Hamilton anxiety rating scale (HAMA) scores were assessed, and rs‐fMRI data were collected. The FC analysis was performed using the NTS as the seed point, and FC values with all voxels in the whole brain were calculated. A two‐sample t‐test was used to compare FC differences between the two groups. The FC values of brain regions with differences were extracted and correlated with clinical scale scores. Results: In comparison to healthy controls, FC values in the NTS and anterior cingulate cortex(ACC) were reduced in patients with chronic cough after lung surgery (GRF correction, p‐voxel < 0.005, p‐cluster < 0.05) which were positively correlated with LCQ‐MC scores (r = 0.534, p = 0.011), but with VAS (r = −0.500, p = 0.018), HAMA (r = −0.713, p < 0.001) scores were negatively correlated. Conclusions: Reduced FC of the NTS with ACC may be associated with cough hypersensitivity and may contribute to anxiety in patients with chronic cough after lung surgery. [ABSTRACT FROM AUTHOR]

Expectations can profoundly modulate pain experience, during which the periaqueductal gray (PAG) plays a pivotal role. In this article, we focus on motivationally evoked neural activations in cortical and brainstem regions both before and during stimulus administration, as has been demonstrated by experimental studies on pain-modulatory effects of expectations, in the hope of unraveling how the PAG is involved in descending and ascending nociceptive processes. This motivational perspective on expectancy effects on the perception of noxious stimuli sheds new light on psychological and neuronal substrates of pain and its modulation, thus having important research and clinical implications. [ABSTRACT FROM AUTHOR]

While the mechanism of general anesthesia has been extensively studied, the underlying neural circuitry has yet to be fully understood. The parabrachial nucleus (PBN) plays a crucial role in modulating wakefulness and promoting arousal from general anesthesia. However, the specific role of PBN projections in the process of general anesthesia remains unclear. In this study, we bilaterally injected AAV-associated viruses encoding excitatory or inhibitory optogenetic probes into the PBN and implanted optical fibers in the LH or BF area. After four weeks, we optogenetically activated or inhibited the PBN-LH and PBN-BF pathways under 1.5 vol% isoflurane. We calculated the time it took for anesthesia induction and emergence, simultaneously monitoring changes in the burst-suppression ratio using electroencephalogram recording. Our findings indicate that optogenetic activation of the PBN-LH and PBN-BF projections plays a significant role in promoting both cortical and behavioral emergence from isoflurane inhalation, without significantly affecting the induction time. Conversely, photoinhibition of these pathways prolonged the recovery time, with no notable difference observed during the induction phase. In summary, our results demonstrate that the PBN-LH and PBN-BF pathways are crucial for promoting arousal from isoflurane general anesthesia, but do not have a pronounced impact on the induction phase. [ABSTRACT FROM AUTHOR]

The conditions of stress contagion are induced in bystanders without direct experiences of stressful events. This study determined the effects of stress contagion on masseter muscle nociception in mice. Stress contagion was developed in the bystanders after cohabitating with a conspecific mouse subjected to social defeat stress for 10 days. On Day 11, stress contagion increased anxiety‐ and orofacial inflammatory pain‐like behaviors. The c‐Fos and FosB immunoreactivities evoked by masseter muscle stimulation were increased in the upper cervical spinal cord, while c‐Fos expressions were increased in the rostral ventromedial medulla, including the lateral paragigantocellular reticular nucleus and nucleus raphe magnus in stress contagion mice. The level of serotonin in the rostral ventromedial medulla was increased under stress contagion, while the number of serotonin positive cells was increased in the lateral paragigantocellular reticular nucleus. Stress contagion increased c‐Fos and FosB expressions in the anterior cingulate cortex and insular cortex, both of which were positively correlated with orofacial inflammatory pain‐like behaviors. The level of brain‐derived neurotrophic factor was increased in the insular cortex under stress contagion. These results indicate that stress contagion can cause neural changes in the brain, resulting in increased masseter muscle nociception, as seen in social defeat stress mice. [ABSTRACT FROM AUTHOR]

The article presents the discussion on effect of greater occipital nerve block (GONB) in migraine. Topics include Prepulse inhibition (PPI) of the BR is a decrease in BR excitability due to the conditioning stimulus and representing sensory gating at the brainstem; and analyzing the electrophysiological findings in patients with the clinical response after GONB.

One challenge in extracting the scalp-recorded frequency-following response (FFR) is related to its inherently small amplitude, which means that the response cannot be identified with confidence when only a relatively small number of recording sweeps are included in the averaging procedure. This study examined how the non-negative matrix factorisation (NMF) algorithm with a source separation constraint could be applied to improve the efficiency of FFR recordings. Conventional FFRs elicited by an English vowel/i/with a rising frequency contour were collected. Study sample: Fifteen normal-hearing adults and 15 normal-hearing neonates were recruited. The improvements of FFR recordings, defined as the correlation coefficient and root-mean-square differences across a sweep series of amplitude spectrograms before and after the application of the source separation NMF (SSNMF) algorithm, were characterised through an exponential curve fitting model. Statistical analysis of variance indicated that the SSNMF algorithm was able to enhance the FFRs recorded in both groups of participants. Such improvements enabled FFR extractions in a relatively small number of recording sweeps, and opened a new window to better understand how speech sounds are processed in the human brain. [ABSTRACT FROM AUTHOR]

Repeat mild traumatic brain injuries (RmTBI) result in substantial burden to the public health system given their association with chronic post-injury pathologies, such as chronic pain and post-traumatic headache. Although this may relate to dysfunctional descending pain modulation (DPM), it is uncertain what mechanisms drive changes within this pathway. One possibility is altered orexinergic system functioning, as orexin is a potent anti-nociceptive neuromodulator. Orexin is exclusively produced by the lateral hypothalamus (LH) and receives excitatory innervation from the lateral parabrachial nucleus (lPBN). Therefore, we used neuronal tract-tracing to investigate the relationship between RmTBI and connectivity between lPBN and the LH, as well as orexinergic projections to a key site within the DPM, the periaqueductal gray (PAG). Prior to injury induction, retrograde and anterograde tract-tracing surgery was performed on 70 young-adult male Sprague Dawley rats, targeting the lPBN and PAG. Rodents were then randomly assigned to receive RmTBIs or sham injuries before undergoing testing for anxiety-like behaviour and nociceptive sensitivity. Immunohistochemical analysis identified distinct and co-localized orexin and tract-tracing cell bodies and projections within the LH. The RmTBI group exhibited altered nociception and reduced anxiety as well as a loss of orexin cell bodies and a reduction of hypothalamic projections to the ventrolateral nucleus of the PAG. However, there was no significant effect of injury on neuronal connectivity between the lPBN and orexinergic cell bodies within the LH. Our identification of structural losses and the resulting physiological changes in the orexinergic system following RmTBI begins to clarify acute post-injury mechanistic changes that drive may drive the development of post-traumatic headache and the chronification of pain. [ABSTRACT FROM AUTHOR]

Aims: Chronic migraine (CM) is a common neurological disorder with complex pathogenesis. Evidence suggests that pituitary adenylate cyclase-activating peptide (PACAP) induces migraine-like attacks and may be potential a new target for migraine treatment, but the therapeutic results of targeting PACAP and its receptors are not uniform. Therefore, the aim of this study was to investigate the regulatory effect of PACAP type I receptor (PAC1R) antagonist, PACAP6-38, on nitroglycerin (NTG)-induced central sensitization in a CM model. Methods: Sprague–Dawley (SD) rats received repeated injections of NTG to construct a CM model. Mechanical and thermal thresholds were measured using Von Frey filaments and hot plate tests. C-Fos expression was measured by western blotting and immunofluorescence staining to assess the central sensitization. PACAP6-38 was intracerebrally injected into the trigeminal nucleus caudalis (TNC), and then the changes in c-Fos, the synaptic-associated proteins, phospho-ERK1/2 (p-ERK1/2), phosphorylation of cyclic adenosine monophosphate response element-binding protein (p-CREB) and brain-derived neurotrophic factor (BDNF) were detected. Transmission electron microscopy (TEM) and Golgi-Cox staining were used to observe the ultrastructure of synapses and dendritic structures of TNC neurons. Results: The results showed that PACAP and PAC1R expression were significantly raised in the TNC after repeated NTG injections. Additionally, PACAP6-38 treatment alleviated nociceptive sensitization, inhibited NTG-induced overexpression of c-Fos and synaptic-associated proteins in the TNC of CM rat, restored aberrant synaptic structures. Furthermore, the expression of ERK/CREB/BDNF pathway was depressed by PACAP6-38. Conclusions: Our results demonstrated that abnormal synaptic structure in the TNC of CM, which could be reversed by inhibition of PAC1R via down-regulating the ERK/CREB/BDNF signaling pathway. PACAP6-38 improves NTG-induced central sensitization by regulating synaptic plasticity in the TNC of CM rat, which may provide new insights into the treatments targeting PACAP/PAC1R in migraine. [ABSTRACT FROM AUTHOR]

Maintaining airway patency during anaesthesia is the primary responsibility of the anaesthesiologist. Apart from anaesthetic agents, there are many factors which influence the pharyngeal patency. Understanding the pharyngeal collapsibility and behaviour of the upper airway during sleep would help in increasing the safety of patients under anaesthesia. The mechanism of pharyngeal collapse, the role of pharyngeal dilators, negative intra-thoracic pressure and multiple other factors involved to maintain pharyngeal patency are described in the article. Clinical and radiological tools to predict upper airway collapsibility have also been explained with supportive evidence. This article should be considered a resource for concepts of pharyngeal dynamics and mechanics to improve airway patency and to predict pharyngeal collapsibility and thereby safety during anaesthesia. [ABSTRACT FROM AUTHOR]

Background: This pilot study examined the relationship between the Coma Recovery Scale-Revised (CRS-R) and the five subparts of the thalamocortical tract in chronic patients with hypoxic–ischemic brain injury by diffusion tensor tractography (DTT). Methods: Seventeen consecutive chronic patients with hypoxic–ischemic brain injury were recruited. The consciousness state was evaluated using CRS-R. The five subparts of the thalamocortical tract (the prefrontal cortex, the premotor cortex, the primary motor cortex, the primary somatosensory cortex, and the posterior parietal cortex) were reconstructed using DTT. Fractional anisotropy and the tract volume of each subpart of the thalamocortical tract were estimated. Results: The CRS-R score showed a moderate positive correlation with the tract volume of the prefrontal cortex part of the thalamocortical tract (p < 0.05). In addition, the tract volume of the prefrontal cortex component of the thalamocortical tract could explain the variability in the CRS-R score (p < 0.05). Conclusion: The prefrontal cortex part was closely related to the CRS-R score in chronic patients with hypoxic–ischemic brain injury. In addition, the change in the remaining number of neural fibers of the prefrontal cortex part appeared to be related to the change in conscious state. [ABSTRACT FROM AUTHOR]

Background: The study was designed to explore the correlation of the asymmetric regulation between periaqueductal gray (PAG) and bilateral trigeminal nucleus caudalis (TNC) in migraine rats through studying the changes of metabolites in pain regulatory pathway of acute migraine attack. Methods: Thirty male Sprague–Dawley (SD) rats were randomly divided into three groups: blank, control, model groups. Then, blank group was intraperitoneally injected with ultrapure water, while control group injected with saline and model group injected with Glyceryl Trinitrate (GTN). Two hours later, PAG and bilateral TNC were removed respectively, and metabolite concentrations of PAG, Left-TNC, Right-TNC were obtained. Lastly, the differences of metabolite among three brain tissues were compared. Results: The relative concentrations of rNAA, rGlu, rGln, rTau, rMI in PAG or bilateral TNC had interaction effects between groups and sites. The concentration of rLac of three brain tissues increased in migraine rats, however, the rLac of LTNC and RTNC increased more than that of PAG. Besides, the concentrations of rNAA and rGln increased in RTNC, while rGABA decreased in RTNC. Conclusions: There is correlation between PAG, LTNC and RTNC in regulation of pain during acute migraine attack, and the regulation of LTNC and RTNC on pain is asymmetric. [ABSTRACT FROM AUTHOR]

Spinal cord stimulation is an increasingly used treatment for a number of chronic pain states. Dorsal column stimulation is historically and currently the anatomical target of choice for most chronic pain conditions, including postlaminectomy syndrome and radicular pain. However, early studies suggested that stimulation of an alternative target, the ventral columns that carry pain fibers in the anterior and lateral spinothalamic tracts, may offer comparable or superior pain relief. A patient undergoing standard-of-care spinal cord stimulation trial had an additional lead placed on the right ventrolateral aspect of the spinal cord. After the usual 7-day trial of dorsal column stimulation, the dorsal leads were removed and ventrolateral column stimulation was applied through the retained ventral lead for a period of 3 days. The Brief Pain Index Short Form and Numeric Rating Scale were recorded for both dorsal and ventral stimulation. Ventrolateral spinal cord stimulation provided comparable outcomes compared with dorsal column stimulation using nonparesthesia-based stimulation. The results suggest further investigation into spinal cord stimulation anatomical placement and mechanism of action is warranted. [ABSTRACT FROM AUTHOR]

Purpose : Neuromelanin MRI (NM-MRI) is applied as a proxy measurement of dopaminergic functioning of the substantia nigra pars compacta (SN). To increase its clinical applicability, a fast and easily applicable NM-MRI sequence is needed. This study therefore compared accelerated NM-MRI sequences using standard available MRI options with a validated 2D gradient recalled echo NM-MRI sequence with off-resonance magnetization transfer (MT) pulse (2D-MToffRes). Methods: We used different combinations of compressed sense (CS) acceleration, repetition times (TR), and MT pulse to accelerate the validated 2D-MToffRes. In addition, we compared a recently introduced 3D sequence with the 2D-MToffRes. Results: Our results show that the 2D sequences perform best with good to excellent reliability. Only excellent intraclass correlation coefficients were found for the CS factor 2 sequences. Conclusion: We conclude that there are several reliable approaches to accelerate NM-MRI, in particular by using CS. [ABSTRACT FROM AUTHOR]

Aim; Autism is a pervasive developmental disorder Deficit; in sensory functions is one of the characteristics of people with autism, and usually these people show abnormality in processing and correct interpretation of auditory information. Also people with Autism show problems in communicating with others. This review article deals with the accurate understanding of Auditory processing skills of autistic children compared to normal children is done to clarify the auditory processing disorder in this group. Information & Methods This systematic review was conducted in articles published from 2002 to 2022 in the field of electrophysiological evaluations of auditory brainstem in autism spectrum disorder by searching Scopus, PubMed, Google Scholar, and Science Direct databases. Finding: Disorders were observed in the brainstem electrophysiological responses of patients with ASD compared to the normal group. The results of studies of auditory brainstem evoked responses with click stimuli showed an increase in wave V latency and I-V interpeak latency in ASD subjects compared to normal groups. Studies of brainstem evoked responses with speech stimuli also showed a decrease in amplitude and an increase in latency. Conclusion Auditory processing disorders in verbal and non-verbal stimuli in people with autism spectrum have been reported. Most studies show disorders in speech stimuli, which play a very important role in communicating. department [ABSTRACT FROM AUTHOR]

Background and Aim: Recreational and occupational noise can cause permanent damage to the inner ear. Cochlear synaptopathy can be “hidden” because this synaptic reduction can occur without permanent hearing threshold changes. Our study aimed to assess synaptopathy in people with and without a history of occupational noise exposure by use of latency shift of wave V with masking. Methods:In this study, 38 males were involved. All participants had normal hearing thresholds. Of 38 males, 20-male identified with exposure to occupational noise and 18 identified without occupational noise exposure. Auditory brainstem response and masked were performed. Results: The main effect of the between-group factor was not significant in the right and left ears. But the main effect of the within-group factor in the right and left ears were significant (p<0.001 and p<0.001). Auditory brainstem response latencies at different levels in each group were significant. These results showed that there were no significant differences between latency changes in both groups. Conclusion: In order to diagnose cochlear synaptopathy in humans it is important to use audiological test batteries in the future. There is currently no effective way to diagnose noise-induced cochlear synaptopathy in human subjects. [ABSTRACT FROM AUTHOR]

While each place on the cochlea is most sensitive to a specific frequency, it will generally respond to a sufficiently high-level stimulus over a wide range of frequencies. This spread of excitation can introduce errors in clinical threshold estimation during a diagnostic auditory brainstem response (ABR) exam. Off-frequency cochlear excitation can be mitigated through the addition of masking noise to the test stimuli, but introducing a masker increases the already long test times of the typical ABR exam. Our lab has recently developed the parallel ABR (pABR) paradigm to speed up test times by utilizing randomized stimulus timing to estimate the thresholds for multiple frequencies simultaneously. There is reason to believe parallel presentation of multiple frequencies provides masking effects and improves place specificity while decreasing test times. Here, we use two computational models of the auditory periphery to characterize the predicted effect of parallel presentation on place specificity in the auditory nerve. We additionally examine the effect of stimulus rate and level. Both models show the pABR is at least as place specific as standard methods, with an improvement in place specificity for parallel presentation (vs. serial) at high levels, especially at high stimulus rates. When simulating hearing impairment in one of the models, place specificity was also improved near threshold. Rather than a tradeoff, this improved place specificity would represent a secondary benefit to the pABR's faster test times. [ABSTRACT FROM AUTHOR]

Older people often show auditory temporal processing deficits and speech-in-noise intelligibility difficulties even when their audiogram is clinically normal. The causes of such problems remain unclear. Some studies have suggested that for people with normal audiograms, age-related hearing impairments may be due to a cognitive decline, while others have suggested that they may be caused by cochlear synaptopathy. Here, we explore an alternative hypothesis, namely that age-related hearing deficits are associated with decreased inhibition. For human adults (N =30) selected to cover a reasonably wide age range (25-59 years), with normal audiograms and normal cognitive function, we measured speech reception thresholds in noise (SRTNs) for disyllabic words, gap detection thresholds (GDTs), and frequency modulation detection thresholds (FMDTs). We also measured the rate of growth (slope) of auditory brainstem response wave-I amplitude with increasing level as an indirect indicator of cochlear synaptopathy, and the interference inhibition score in the Stroop color and word test (SCWT) as a proxy for inhibition. As expected, performance in the auditory tasks worsened (SRTNs, GDTs, and FMDTs increased), and wave-I slope and SCWT inhibition scores decreased with ageing. Importantly, SRTNs, GDTs, and FMDTs were not related to wave-I slope but worsened with decreasing SCWT inhibition. Furthermore, after partialling out the effect of SCWT inhibition, age was no longer related to SRTNs or GDTs and became less strongly related to FMDTs. Altogether, results suggest that for people with normal audiograms, age-related deficits in auditory temporal processing and speech-innoise intelligibility are mediated by decreased inhibition rather than cochlear synaptopathy. [ABSTRACT FROM AUTHOR]

Copyright of Minas Gerais Medical Journal / Revista Médica de Minas Gerais is the property of Associacao Medica de Minas Gerais and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Our previous studies found that electroacupuncture at the right Zhongzhu acupoint (TE3) can enhance auditory recovery in rats with noise-induced hearing loss. Here, we investigated the changes in auditory brainstem response (ABR) and long late latency (LLR) evoked potential to explain the mechanisms of electroacupuncture at TE3. The auditory evoked potentials were recorded, including ABR and LLR, at baseline and on day 3 (D3), D5, and D8 after baseline. The 2-Hz electroacupuncture at the right TE3 was applied on D3, D4, and D5 in the electroacupuncture group but not in the control group. In ABR, compared with the control group, the latency shift of waves I (0.298 ± 0.033 vs −0.045 ± 0.057 ms), III (0.718 ± 0.038 vs −0.163 ± 0.130 ms), and V (1.160 ± 0.082 vs −0.207 ± 0.138 ms) on D3 (all p < 0.01) and of wave V (0.616 ± 0.433 vs −0.352 ± 0.209 ms, p < 0.05) on D5 was greater in the electroacupuncture group than that in the control group. Moreover, the interpeak latency shift of I–III (0.420 ± 0.041 vs −0.118 ± 0.177 ms) and I–V (0.863 ± 0.088 vs −0.162 ± 0.156 ms) on D3 (both p < 0.05) and of III–V (0.342 ± 0.193 vs −0.190 ± 0.110 ms) and I–V (0.540 ± 0.352 vs −0.343 ± 0.184 ms) on D5 (both p < 0.05) was greater in the electroacupuncture group than that in the control group. In LLR, the latency shift of P0 was greater in the electroacupuncture group than in the control group on D3 (3.956 ± 2.975 vs −1.178 ± 1.358 ms, p < 0.01) and D5 (2.200 ± 1.889 vs −0.311 ± 1.078 ms, p < 0.05). These findings indicate that electroacupuncture at the right TE3 can modulate the neuroplasticity of the central auditory pathway, including the brain stem and the primary and secondary auditory cortex. [ABSTRACT FROM AUTHOR]

Background: Neural circuits produce reliable activity patterns despite disturbances in the environment. For this to occur, neurons elicit synaptic plasticity during perturbations. However, recent work suggests that plasticity not only regulates circuit activity during disturbances, but these modifications may also linger to stabilize circuits during future perturbations. The implementation of such a regulation scheme for real-life environmental challenges of animals remains unclear. Amphibians provide insight into this problem in a rather extreme way, as circuits that generate breathing are inactive for several months during underwater hibernation and use compensatory plasticity to promote ventilation upon emergence., Results: Using ex vivo brainstem preparations and electrophysiology, we find that hibernation in American bullfrogs reduces GABA A receptor (GABA A R) inhibition in respiratory rhythm generating circuits and motor neurons, consistent with a compensatory response to chronic inactivity. Although GABA A Rs are normally critical for breathing, baseline network output at warm temperatures was not affected. However, when assessed across a range of temperatures, hibernators with reduced GABA A R signaling had greater activity at cooler temperatures, enhancing respiratory motor output under conditions that otherwise strongly depress breathing., Conclusions: Hibernation reduces GABA A R signaling to promote robust respiratory output only at cooler temperatures. Although frogs do not ventilate lungs during underwater hibernation, we suggest this would be beneficial for stabilizing breathing when the animal passes through a large temperature range during emergence in the spring. More broadly, these results demonstrate that compensatory synaptic plasticity can increase the operating range of circuits in harsh environments, thereby promoting adaptive behavior in conditions that suppress activity., (© 2024. The Author(s).)

Deriving human neural responses to natural speech is now possible, but the responses to male- and female-uttered speech have been shown to differ. These talker differences may complicate interpretations or restrict experimental designs geared toward more realistic communication scenarios. This study found that when a male talker and a female talker had the same fundamental frequency, auditory brainstem responses (ABRs) were very similar. Those responses became smaller and later with increasing fundamental frequency, as did click ABRs with increasing stimulus rates. Modeled responses suggested that the speech and click ABR differences were reasonably predicted by peripheral and brainstem processing of stimulus acoustics., (© 2024 Acoustical Society of America.)

Neuronal activity requires a large amount of ATP, leading to a rapid collapse of brain function when aerobic respiration fails. Here, we summarize how rhythmic motor circuits in the brain stem of adult frogs, which normally have high metabolic demands, transform to produce proper output during severe hypoxia associated with emergence from hibernation. We suggest that general principles underlying plasticity in brain bioenergetics may be uncovered by studying nonmammalian models that face extreme environments, yielding new insights to combat neurological disorders involving dysfunctional energy metabolism.

Background: The brainstem is a crucial component of the central autonomic nervous (CAN) system. Functional MRI (fMRI) of the brainstem remains challenging due to a range of factors, including diverse imaging protocols, analysis, and interpretation., Purpose: To develop an fMRI protocol for establishing a functional atlas in the brainstem., Study Type: Prospective cross-sectional study., Subjects: Ten healthy subjects (four males, six females)., Field Strength/sequence: Using a 3.0 Tesla MR scanner, we acquired T1-weighted images and three different fMRI scans using fMRI protocols of the optimized functional Imaging of Brainstem (FIBS), the Human Connectome Project (HCP), and the Adolescent Brain Cognitive Development (ABCD) project., Assessment: The temporal signal-to-noise-ratio (TSNR) of fMRI data was compared between the FIBS, HCP, and ABCD protocols. Additionally, the main normalization algorithms (i.e., FSL-FNIRT, SPM-DARTEL, and ANTS-SyN) were compared to identify the best approach to normalize brainstem data using root-mean-square (RMS) error computed based on manually defined reference points. Finally, a functional autonomic brainstem atlas that maps brainstem regions involved in the CAN system was defined using meta-analysis and data-driven approaches., Statistical Tests: ANOVA was used to compare the performance of different imaging and preprocessing pipelines with multiple comparison corrections (P ≤ 0.05). Dice coefficient estimated ROI overlap, with 50% overlap between ROIs identified in each approach considered significant., Results: The optimized FIBS protocol showed significantly higher brainstem TSNR than the HCP and ABCD protocols (P ≤ 0.05). Furthermore, FSL-FNIRT RMS error (2.1 ± 1.22 mm; P ≤ 0.001) exceeded SPM (1.5 ± 0.75 mm; P ≤ 0.01) and ANTs (1.1 ± 0.54 mm). Finally, a set of 12 final brainstem ROIs with dice coefficient ≥0.50, as a step toward the development of a functional brainstem atlas., Data Conclusion: The FIBS protocol yielded more robust brainstem CAN results and outperformed both the HCP and ABCD protocols., Evidence Level: 2 TECHNICAL EFFICACY: Stage 1., (© 2024 The Authors. Journal of Magnetic Resonance Imaging published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

tDCS is widely assumed to cause neuromodulation via the electric field in the cortex acting directly on cortical neurons. However, recent evidence suggests that tDCS may indirectly influence brain activity through cranial nerve pathways, notably the trigeminal nerve, but these neuromodulatory pathways remain unexplored. To investigate the first stages in this potential pathway we developed an animal model to study the effect of trigeminal nerve direct current stimulation (TN-DCS) on neuronal activity in the principal sensory nucleus (NVsnpr) and the mesencephalic nucleus of the trigeminal nerve (MeV). We conducted experiments on twenty-four male Sprague Dawley rats (n = 10 NVsnpr, n = 10 MeV during anodic stimulation, and n = 4 MeV during cathodic stimulation). DC stimulation, ranging from 0.5 to 3 mA, targeted the trigeminal nerve's marginal branch. Concurrently, single-unit electrophysiological recordings were obtained using a 32-channel silicon probe, encompassing three 1-min intervals: pre, during, and post-stimulation. Xylocaine trigeminal nerve blockage served as a control. TN-DCS increased neuronal spiking activity in both NVsnpr and MeV, returning to baseline during the post-stimulation phase. The 3 mA DC stimulation of the blocked trigeminal nerve failed to induce increased spiking activity in the trigeminal nuclei. These findings provide empirical support for trigeminal nuclei modulation via TN-DCS, suggesting the cranial nerve pathways could play a role in mediating the tDCS effects in humans., (© 2024. The Author(s).)

The brainstem is a hub for sensorimotor integration, which mediates crucial innate behaviors. This brain region is characterized by a rich population of GABAergic inhibitory neurons, required for the proper expression of these innate behaviors. However, what roles these inhibitory neurons play in innate behaviors and how they function are still not fully understood. Here, we show that inhibitory neurons in the nucleus of the optic tract and dorsal-terminal nuclei (NOT-DTN) of the mouse can modulate the innate eye movement optokinetic reflex (OKR) by shaping the tuning properties of excitatory NOT-DTN neurons. Specifically, we demonstrate that although these inhibitory neurons do not directly induce OKR, they enhance the visual feature selectivity of OKR behavior, which is mediated by the activity of excitatory NOT-DTN neurons. Moreover, consistent with the sharpening role of inhibitory neurons in OKR behavior, they have broader tuning relative to excitatory neurons. Last, we demonstrate that inhibitory NOT-DTN neurons directly provide synaptic inhibition to nearby excitatory neurons and sharpen their tuning in a sustained manner, accounting for the enhanced feature selectivity of OKR behavior. In summary, our findings uncover a fundamental principle underlying the computational role of inhibitory neurons in brainstem sensorimotor circuits., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Anesthesia modifies sensory representations in the thalamo-cortical circuit but is considered to have a milder impact on peripheral sensory processing. Here, tracking the same neurons across wakefulness and isoflurane or ketamine medetomidine anesthesia, we show that the amplitude and sign of single neuron responses to sounds are massively modified by anesthesia in the cochlear nucleus of the brainstem, the first relay of the auditory system. The reorganization of activity is so profound that decoding of sound representation under anesthesia is not possible based on awake activity. However, population-level parameters, such as average tuning strength and population decoding accuracy, are weakly affected by anesthesia, explaining why its effect has previously gone unnoticed when comparing independently sampled neurons. Together, our results indicate that the functional organization of the auditory brainstem largely depends on the network state and is ill-defined under anesthesia. This demonstrates a remarkable sensitivity of an early sensory stage to anesthesia, which is bound to disrupt downstream processing.

Silicon multielectrode-based recordings are increasingly popular for studying neuronal activity at the temporal resolution of action potentials in many brain regions. However, recording neuronal activity from deep caudal structures like the brainstem using multi-channel probes remains challenging. A significant concern is finding a trajectory for probe insertion that avoids large blood vessels, such as the superior sagittal venous sinus and the transverse venous sinus. Injuring these large veins can cause extensive bleeding, damage to the underlying brain tissue, and potentially death. This approach describes targeting brainstem structures by coupling anterior coordinates with an angled approach, allowing the recording probe to penetrate the brain below high-risk vascular structures. Compared to a strictly vertical approach, the angled approach maximizes the number of brain regions that can be targeted. Using this strategy, the ventrolateral periaqueductal gray (vlPAG), a brainstem region associated with REM sleep, can be reproducibly and reliably accessed to obtain single-unit, multi-electrode recordings in head-fixed mice before and during sevoflurane anesthesia. The ability to record neuronal activity in the vlPAG and surrounding nuclei with high temporal resolution is a step forward in advancing the understanding of the relationship between REM sleep and anesthesia.

Sleep behavior is present in nearly all animals, and is a vital part of growth, development, and overall health. Infant mammals cycle randomly between short bouts of sleep and wake, and the lengths of these bouts both follow an exponential distribution. As mammals mature into adulthood, the mean sleep and wake bout lengths increase, and we also observe a change in the distribution of wake bout lengths from exponential to power law. Focusing on three regions of the brainstem that are involved in sleep-wake regulation, we develop a novel integrate-and-fire neuronal network model to expand upon previous mathematical models of sleep-wake regulation in mammals, focusing on rats. This model allows fine control over neuronal connectivity while simultaneously increasing the size and complexity of the modeled system to make it more representative of reality. We establish a relationship between neuronal network structure and function that could explain the different sleep-wake behaviors observed in rats as they progress through development. We explore the relationship between three different neuronal populations as well as the overall network behavior of the system. We find that increasing synaptic connectivity strength between the wake-promoting region and the wake-active region accounts for the observed changes in mammalian sleep-wake patterns. This dynamic neuronal connectivity is a possible mechanism that accurately accounts for sleep-wake pattern changes observed during mammalian development., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Samberg, Schmidt. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The binaural interaction component (BIC) of the auditory evoked potential is the difference between the waveforms of the binaural response and the sum of left and right monaural responses. This investigation examined BICs of the auditory brainstem (ABR) and middle-latency (MLR) responses concerning three objectives: 1) the level of the auditory system at which low-frequency dominance in BIC amplitudes begins when the binaural temporal fine structure is more influential with lower- than higher-frequency content; 2) how BICs vary as a function of frequency and lateralization predictability, as could relate to the improved lateralization of high-frequency sounds; 3) how attention affects BICs. Sixteen right-handed participants were presented with either low-passed (< 1000 Hz) or high-passed (> 2000 Hz) clicks at 30 dB SL with a 38 dB (A) masking noise, at a stimulus onset asynchrony of 180 ms. Further, this repeated-measures design manipulated stimulus presentation (binaural, left monaural, right monaural), lateralization predictability (unpredictable, predictable), and attended modality (either auditory or visual). For the objectives, respectively, the results were: 1) whereas low-frequency dominance in BIC amplitudes began during, and continued after, the Na-BIC, binaural (center) as well as summed monaural (left and right) amplitudes revealed low-frequency dominance only after the Na wave; 2) with a predictable position that was fixed, no BIC exhibited equivalent amplitudes between low- and high-passed clicks; 3) whether clicks were low- or high-passed, selective attention affected the ABR-BIC yet not MLR-BICs. These findings indicate that low-frequency dominance in lateralization begins at the Na latency, being independent of the efferent cortico-collicular pathway's influence., Competing Interests: Declaration of competing interest None., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Resistance to stress is a key determinant for mammalian functioning. While many studies have revealed neural circuits and substrates responsible for initiating and mediating stress responses, little is known about how the brain resists to stress and prevents overreactions. Here, we identified a previously uncharacterized neuropeptide Y (NPY) neuronal population in the dorsal raphe nucleus and ventrolateral periaqueductal gray region (DRN/vlPAG) with anxiolytic effects in male mice. NPY DRN/vlPAG neurons are rapidly activated by various stressful stimuli. Inhibiting these neurons exacerbated hypophagic and anxiety responses during stress, while activation significantly ameliorates acute stress-induced hypophagia and anxiety levels and transmits positive valence. Furthermore, NPY DRN/vlPAG neurons exert differential but synergic anxiolytic effects via inhibitory projections to the paraventricular thalamic nucleus (PVT) and the lateral hypothalamic area (LH). Together, our findings reveal a feedforward inhibition neural mechanism underlying stress resistance and suggest NPY DRN/vlPAG neurons as a potential therapeutic target for stress-related disorders., (© 2024. The Author(s).)

Coughing is a respiratory behavior that plays a crucial role in protecting the respiratory system. Here we show that the nucleus of the solitary tract (NTS) in mice contains heterogenous neuronal populations that differentially control breathing. Within these subtypes, activation of tachykinin 1 (Tac1)-expressing neurons triggers specific respiratory behaviors that, as revealed by our detailed characterization, are cough-like behaviors. Chemogenetic silencing or genetic ablation of Tac1 neurons inhibits cough-like behaviors induced by tussive challenges. These Tac1 neurons receive synaptic inputs from the bronchopulmonary chemosensory and mechanosensory neurons in the vagal ganglion and coordinate medullary regions to control distinct aspects of cough-like defensive behaviors. We propose that these Tac1 neurons in the NTS are a key component of the airway-vagal-brain neural circuit that controls cough-like defensive behaviors in mice and that they coordinate the downstream modular circuits to elicit the sequential motor pattern of forceful expiratory responses., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)

All terrestrial vertebrate life must transition from aquatic gas exchange in the embryonic environment to aerial or pulmonary respiration at birth. In addition to being able to breathe air, neonates must possess functional sensory feedback systems for maintaining acid-base balance. Respiratory neurons in the brainstem act as pH sensors that can adjust breathing to regulate systemic pH. The central pH sensitivity of breathing-related motor output develops over the embryonic period in the zebra finch (Taeniopygia guttata). Due to the key role of chloride ions in electrochemical stability and developmental plasticity, we tested chloride's role in the development of central pH sensitivity. We blocked gamma-aminobutyric acid-A receptors and cation-chloride cotransport that subtly modulated the low-pH effects on early breathing biorhythms. Further, chloride-free artificial cerebrospinal fluid altered the pattern and timing of breathing biorhythms and blocked the stimulating effect of acidosis in E12-14 brainstems. Early and middle stage embryos exhibited rebound plasticity in brainstem motor outputs during low-pH treatment, which was eliminated by chloride-free solution. Results show that chloride modulates low-pH sensitivity and rebound plasticity in the zebra finch embryonic brainstem, but work is needed to determine the cellular and circuit mechanisms that control functional chloride balance during acid-base disturbances., (© 2024 Wiley Periodicals LLC.)

Abstract: Neuroimaging studies have revealed important pathomechanisms related to disorders of brain-gut interactions, such as irritable bowel syndrome and functional dyspepsia. More detailed investigations aimed at neural processing in the brainstem, including the key relay station of the nucleus of the solitary tract (NTS), have hitherto been hampered by technical shortcomings. To ascertain these processes in more detail, we used multiecho multiband 7T functional magnetic resonance imaging and a novel translational experimental model based on a nutrient-derived intestinal chemonociceptive stimulus. In a randomized cross-over fashion, subjects received duodenal infusion of capsaicin (the pungent principle in red peppers) and placebo (saline). During infusion, functional magnetic resonance imaging data and concomitant symptom ratings were acquired. Of 26 healthy female volunteers included, 18 were included in the final analysis. Significantly increased brain activation over time during capsaicin infusion, as compared with placebo, was observed in brain regions implicated in pain processing, in particular the NTS. Brain activation in the thalamus, cingulate cortex, and insula was more pronounced in subjects who reported abdominal pain (visual analogue scale > 10 mm), as compared with subjects who experienced no pain. On the contrary, activations at the level of the NTS were independent of subjective pain ratings. The current experimental paradigm therefore allowed us to demonstrate activation of the principal relay station for visceral afferents in the brainstem, the NTS, which was engaged irrespective of the conscious pain response. These findings contribute to understanding the fundamental mechanism necessary for developing novel therapies aimed at correcting disturbances in visceral afferent pain processing. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study was to determine if and how the subcortical neural representation of pitch cues in listeners with normal hearing is affected by systematic manipulation of vocoder parameters. Method: This study assessed the effects of temporal envelope cutoff frequency (50 and 500 Hz), number of channels (1-32), and carrier type (sine-wave and noise-band) on brainstem neural representation of fundamental frequency (fo) in frequency-following responses (FFRs) to vocoded vowels of 15 young adult listeners with normal hearing. Results: Results showed that FFR fo strength (quantified as absolute fo magnitude divided by noise floor [NF] magnitude) significantly improved with 500-Hz vs. 50-Hz temporal envelopes for all channel numbers and both carriers except the 1-channel noise-band vocoder. FFR fo strength with 500-Hz temporal envelopes significantly improved when the channel number increased from 1 to 2, but it either declined (sine-wave vocoders) or saturated (noise-band vocoders) when the channel number increased from 4 to 32. FFR fo strength with 50-Hz temporal envelopes was similarly small for both carriers with all channel numbers, except for a significant improvement with the 16-channel sine-wave vocoder. With 500-Hz temporal envelopes, FFR fo strength was significantly greater for sine-wave vocoders than for noise-band vocoders with channel numbers 1-8; no significant differences were seen with 16 and 32 channels. With 50-Hz temporal envelopes, the carrier effect was only observed with 16 channels. In contrast, there was no significant carrier effect for the absolute fo magnitude. Compared to sine-wave vocoders, noise-band vocoders had a higher NF and thus lower relative FFR fo strength. Conclusions: It is important to normalize the fo magnitude relative to the NF when analyzing the FFRs to vocoded speech. The physiological findings reported here may result from the availability of fo-related temporal periodicity and spectral sidelobes in vocoded signals and should be considered when selecting vocoder parameters and interpreting results in future physiological studies. In general, the dependence of brainstem neural phase-locking strength to fo on vocoder parameters may confound the comparison of pitch-related behavioral results across different vocoder designs. [ABSTRACT FROM AUTHOR]

Purpose: The Vibrant Soundbridge (VSB) active middle ear implant can be used to treat adults and children with hearing loss. Intraoperative measurements based on auditory brainstem response (ABR) allow the determination of the implant's performance. Two methods for stimulus presentation during ABR measurements via VSB will be compared. Method: ABRs were measured in patients implanted with a VSB using a standard ABR system. The stimulus was transmitted directly to the VSB using a new transmission unit (AcoustiAP, MED-EL) and for comparison via a standard audio processor coupled to a wireless streaming device. The study included 10 subjects with mild-to-profound sensorineural, conductive, or mixed hearing loss. Results: As opposed to the wireless method, the AcoustiAP transmits the ABR stimulus without additional signal processing. Therefore, only minor distortions of the transmitted signal are to be expected. There was no significant difference between the performance of the two methods (mean wave V amplitudes 313 [75.2] vs. 301 [88.2] nVpp). In addition, the new system allowed for a more stable connection to the implant system. Conclusion: The AcoustiAP is a valuable tool for performing ABR measurements in patients during VSB implantation using standard equipment, as it allows for easier and more controlled measurements of the coupling efficiency of the implant. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Health & Life Sciences / Sağlık ve Yaşam Bilimleri Dergisi is the property of Istanbul Kultur University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: In this study, the development of a quantitative measurement method to predict long-term auditory adaptation through the stimuli that have been modulated according to different short-term modulation types was aimed to form a psychoacoustic test battery. It might be used in the evaluation process of individuals with hidden hearing loss.Methods: The individuals participating in our study were separated into two groups: high-risk group (n = 39) and low-risk group (n = 30) according to the noise-exposure score. To all participants, auditory brainstem response (ABR), dichotically digit test, Turkish matrix sentence test, otoacoustic emissions test, amplitude modulation detection test, and loudness adaptation test were applied. Stimuli, used in loudness adaptation tests, were provided in three different experiment pairs (experiment 1-2, experiment 3-4, and experiment 5-6).Results: The amplitude of wave I of ABR increased as the intensity level increased in the low-risk group, whereas the amplitude reduced as the intensity level increased in the high-risk group (P < 0.05). When different carrier frequency stimuli were used in amplitude modulation detection test, we found that loudness adaptation was highest at 1 kHz carrier frequency with background noise (P < 0.05).Conclusion: We observed that individuals assumed having hidden hearing loss had high adaptation scores. It was thought that this result might be related to auditory nerve fibers with low spontaneous rate and thus distortion in temporal coding skills might lead to abnormal loudness adaptation, especially with contralateral noise. [ABSTRACT FROM AUTHOR]