Inhibitory Reflex Research Articles

Coordination of Pharyngeal and Esophageal Phases of Swallowing.

Although swallowing has been reviewed extensively, the coordination of the phases of swallowing have not. The phases are controlled by the brainstem, but peripheral factors help coordinate the phases. The occurrence, magnitude, and duration of esophageal phase depends upon peripheral feedback activated by the bolus. The esophageal phase does not occur without peripheral feedback from the esophagus. This feedback is mediated by esophageal slowly-adapting mucosal tension receptors through the recurrent and superior laryngeal nerves. A similar reflex mediated by the same peripheral pathway is the activation of swallowing by stimulation of the cervical esophagus. This reflex occurs primarily in human infants and animals, and this reflex may be important for protecting against aspiration after esophago-pharyngeal reflux. Not only are there inter-phase excitatory processes, but also inhibitory processes. A significant inhibitory process is deglutitive inhibition. When one swallows faster than peristalsis ends, peristalsis is inhibited by the new pharyngeal phase. This process prevents the ongoing esophageal peristaltic wave from blocking the bolus being pushed into the esophagus by the new wave. The esophageal phase returns during the last swallow of the sequence. This process is probably mediated by mucosal tension receptors through the superior laryngeal nerves. A similar reflex exists, the pharyngo-esophageal inhibitory reflex, but studies indicate that it is controlled by a different neural pathway. The pharyngo-esophageal inhibitory reflex is mediated by mucosal tension receptors through the glossopharyngeal nerve. In summary, there are significant peripheral processes that contribute to swallowing, whereby one phase of swallowing significantly affects the other.

A Systematic Review on Sex Differences in Prepulse Inhibition of Startle

Abstract: Prepulse inhibition of the startle response is defined as the inhibition of the startle reflex to an intense contextual stimulus (named pulse) when a weaker stimulus (named prepulse) precedes it and is considered a measure of sensorimotor gating. Consistent with recent research, it has been observed that this measure might exhibit sex differences in studies of both humans and rodents, although the results in the literature appear to be inconsistent. Therefore, this systematic review aims to analyze the sexual differences observed in human and nonhuman animal studies from a comparative perspective. A comprehensive search was conducted from the inception to the present in the Web of Science, PubMed, and PsycInfo databases. Following the search, 58 studies were included in the review. The average age in human studies ( n = 32) was 31.45 years (range = 4–69), while among nonhuman animal studies ( n = 26), the average age was 75.5 postnatal days (range = 7–360). The results indicated no clear sexual differences in the startle response magnitude. However, consistent sex differences in prepulse inhibition were found, revealing that males exhibited higher levels of sensorimotor gating compared to females in both humans (78.79% of the studies) and nonhuman animal studies (69.23% of the studies). Therefore, the findings corroborate the sex differences of prepulse inhibition and underscore the value of this paradigm in comparative science, emphasizing the importance of considering sex as an independent variable when studying this phenomenon.

Clinical and Video-Oculographic Characteristics of Spinocerebellar Ataxia Type 27B (GAA-FGF14 Ataxia): A Single-Center Retrospective Study

An intronic GAA repeat expansion in the FGF14 gene was recently identified as a common cause of autosomal dominant GAA-FGF14 ataxia (SCA27B). We aimed to characterize in detail the clinical and video-oculographic features in our cohort of SCA27B patients. We genotyped the FGF14 GAA repeat expansion in 52 patients with unsolved late-onset cerebellar ataxia. Brain MRI and nerve conduction study, as well as video-oculographic (VOG) assessment, were performed. Eight patients (15.4%) with pathogenic GAA repeat expansion in the FGF14 gene were found. The median age at onset was 51 years (range—23–63 years). Sensory axonal neuropathy was found in 5/8 patients. Cerebellar atrophy was observed in 5/8 patients, and in one case, pontocerebellar atrophy was found. All tested patients had impaired smooth pursuit, 5/6 patients had impaired vestibulo-ocular reflex suppression, nystagmus, and an increased number of square wave jerks, 4/6 patients had horizontal gaze-evoked nystagmus, 3/6 had spontaneous downbeat nystagmus, and 1/6 had an upbeat one. Video head impulse test gain was lower than 0.8 on both sides in 2/4 patients, along with the presence of overt saccades. Further studies in different cohorts are needed to complete the phenotype of the FGF14-related disorders.

Partial chemogenetic inhibition of the locus coeruleus due to heterogeneous transduction of noradrenergic neurons preserved auditory salience processing in wild-type rats.

The acoustic startle reflex (ASR) and prepulse inhibition of the ASR (PPI) assess the efficiency of salience processing, a fundamental brain function that is impaired in many psychiatric conditions. Both ASR and PPI depend on noradrenergic transmission, yet the modulatory role of the locus coeruleus (LC) remains controversial. Clonidine (0.05 mg/kg, i.p.), an alpha2-adrenoreceptor agonist, strongly reduced the ASR amplitude. In contrast, chemogenetic LC inhibition only mildly suppressed the ASR and did affect the PPI in virus-transduced rats. The canine adenovirus type 2 (CAV2)-based vector carrying a gene cassette for the expression of inhibitory receptors (hM4Di) and noradrenergic cell-specific promoter (PRSx8) had high cell-type specificity (94.4±3.1%) but resulted in heterogeneous virus transduction of DbH-positive LC neurons (range: 9.2-94.4%). Clozapine-N-oxide (CNO; 1mg/kg, i.p.), a hM4Di actuator, caused the firing cessation of hM4Di-expressing LC neurons, yet complete inhibition of the entire population of LC neurons was not achieved. Case-based immunohistochemistry revealed that virus injections distal (> 150μm) to the LC core resulted in partial LC transduction, while proximal (< 50 μm) injections caused neuronal loss due to virus neurotoxicity. Neither the ASR nor PPI differed between the intact and virus-transduced rats. Our results suggest that a residual activity of virus-non-transduced LC neurons might have been sufficient for mediating an unaltered ASR and PPI. Our study highlights the importance of a case-based assessment of the virus efficiency, specificity, and neurotoxicity for targeted cell populations and of considering these factors when interpreting behavioral effects in experiments employing chemogenetic modulation.

The long-term post-surgical outcome of intermediate anorectal malformation in our department.

Posterior sagittal anorectoplasty and laparoscopic-assisted anorectal pull-through are preferred for anorectal malformation (ARM) today, while careful pull-through procedures with sacroperineal approach yield excellent outcomes. This study focuses on a pull-through procedure emphasizing continence mechanism preservation and compares outcomes with historical studies with various procedures. Bowel function of patients with intermediate ARM followed up for over 10years post-surgically was assessed. Data collected included ARM type with the Krickenbeck classification, comorbidities, complications, post-surgical examinations, follow-up, and bowel function at the latest clinic visit. The literature review collected original articles including more than 10 post-anorectoplasty cases which were followed for over 10years. Eleven cases were identified, with a median age at anorectoplasty and follow-up length of 6.9months and 14.4years. Two fistula recurrences required surgical treatment. Long-term incontinence and constipation were observed in 9% and 45% of the cohort, respectively. Good rectal angulation and a positive rectoanal inhibitory reflex were confirmed in most cases examined. A literature review identified eight studies with various outcome-measuring instruments. Outcomes of the introduced pull-through procedure were favorable, while the literature review highlights the variation in outcomes of various anorectoplasty. Level IV.

Further insights into anti-IgLON5 disease: a case with complex clinical presentation

BackgroundAnti-IgLON5 disease is an autoimmune encephalitis overlapping with neurodegenerative disorders due to pathological accumulation of hyperphosphorylated tau. It is characterized by several clinical manifestations determined by involvement of different brain areas, and mild response to first-line immunotherapies. We report a case of anti-IgLON5 disease with a multifaceted semiology and an unusually good response to glucocorticoid monotherapy.Case presentationA 68-year-old man with type 2 diabetes was evaluated for an 8-month history of progressive gait disorder causing frequent falls. He also suffered from obstructive sleep apneas and complained of dysphonia, dysarthria, occasional dysphagia, urinary incontinence, and upper limb action tremor. Neurological examination demonstrated bilateral eyelid ptosis, limitation of ocular horizontal smooth pursuit movements, slow horizontal saccades, and lack of inhibition of the vestibulo-ocular reflex during rapid horizontal head torsions. The patient also displayed involuntary, slow, rhythmic movements of the left periorbital and perioral muscles, spreading to the ipsilateral hemipalate and hemitongue, along with bilateral negative upper limb myoclonus. There were proximal muscle wasting in the upper limbs, proximal weakness of the four limbs, and diffuse fasciculations. Ataxia of stance and gait and of the four limbs was noted. MRI of the brain and spine was unremarkable; nerve conduction studies revealed a chronic, predominantly demyelinating, sensory-motor polyneuropathy, probably due to diabetes. Routine CSF examination was unrevealing and serum GFAP level was 89.6 pg/mL; however, the autoimmunity tests revealed a high-titer positivity for anti-IgLON5 autoantibodies in both CSF and serum, leading to the diagnosis of anti-IgLON5 disease. Symptoms improved significantly after intravenous methylprednisolone.ConclusionsHemifacial and hemiorolingual myorhythmia along with peculiar oculomotor abnormalities characterizes the multifaceted clinical picture of our case. The complex semiology of our patient may reflect multifocal targeting of the autoimmune process or sequential spreading of tau inclusions in different brain areas. Our patient’s optimal response to glucocorticoid monotherapy could be underpinned by a slightly different phenotype in which autoimmunity plays a greater pathogenic role than tauopathy, with a lower burden of tau deposition. In such patients, neurodegeneration and tau accumulation could be merely secondary to immune-mediated neuronal dysfunction, supporting the existence of a group of glucocorticoid-responsive patients.

The Relationship Between Neighborhood Disadvantage and Markers of Chronic Pain Risk: Findings From the Oklahoma Study of Native American Pain Risk (OK-SNAP)

Socioeconomic disadvantage contributes to health inequities, including chronic pain. Yet, research examining socioeconomic disadvantage and pain risk in Native Americans (NAs) is scant. This exploratory analysis assessed relationships between socioeconomic position (SEP), ethnicity, and neighborhood disadvantage on pronociceptive processes in 272 healthy, chronic pain-free NAs (n = 139) and non-Hispanic Whites (NHWs, n = 133) from the Oklahoma Study of Native American Pain Risk (OK-SNAP). Neighborhood disadvantage was quantified using the Area Deprivation Index (ADI). Regression models tested whether ADI predicted pain-promoting outcomes (ie, peripheral fiber functionality, pain sensitivity, pain and nociceptive amplification, and endogenous pain inhibition) above-and-beyond SEP and ethnicity. The Ethnicity × ADI interaction was also tested. Of the 11 outcomes tested, 9 were not statistically significant. Of the significant findings, neighborhood disadvantage predicted impaired inhibition of the nociceptive flexion reflex above-and-beyond SEP and ethnicity. Additionally, ethnicity moderated the relationship between ADI and warm detection threshold; disadvantage was associated with higher thresholds for NAs, but not for NHWs. Together, the results suggest neighborhood disadvantage is associated with reduced C-fiber function and impaired spinal inhibition, thus pointing to a role of neighborhood disadvantage in the relationship between the environment and pain inequities. PerspectiveThis study assessed neighborhood socioeconomic disadvantage and pronociceptive processes in chronic pain-free Native Americans (NAs) and non-Hispanic Whites (NHWs). Irrespective of ethnicity, greater neighborhood disadvantage predicted less descending inhibition of spinal nociception. Neighborhood disadvantage was associated with a marker of C-fiber impairment (higher warm detection threshold) in NAs only.

Exploring physiotherapy strategies in arthrogenic muscle inhibition: A scoping review

Arthrogenic muscular inhibition (AMI) is the presynaptic continual reflex inhibition of the surrounding muscles. It is a defensive reaction that lowers motor neuron activity to prevent further damage; however, if it persists, it can cause muscle atrophy and weakness, which can cause functional limitations. It usually involves quadriceps muscle post knee injuries and surgeries. Though it can be appreciated at any joint post injury or surgery like shoulder , elbow and ankle. Recent studies shows that post injury or surgery, tissues respond by reflex inhibition mechanism and is unnoticed by many therapists. The aim of this review is to analyse the various approaches available in the physiotherapy rehabilitation for treating AMI of any joint and to know the best treatment approach to be used for optimising the effects of AMI. Total of 37 articles were considered to identify the different outcomes and interventions used in treating AMI. In conclusion, Effective physiotherapy interventions are necessary to address AMI and enhance joint function and muscle activation. NMES, cryotherapy, and certain strengthening exercises are a few examples of interventions that can help get past the neural inhibition limiting muscle activation surrounding an injured joint. The implementation of early physiotherapy interventions is essential for preventing muscle atrophy and regaining normal movement patterns. In order to advance patient rehabilitation and maximize healing and functional outcomes, a customized protocol with particular demands is required.

Anorectal physiology and colonic motility in children with a history of tethered cord syndrome.

The understanding of the impact of tethered cord syndrome (TCS) on the physiology of the colorectal area is limited. Our aim was to describe anorectal and colonic motility in children with TCS and compare the findings to those of children with functional constipation (FC). We conducted a retrospective review of children with TCS who had an anorectal manometry (ARM) performed at our institution from January 2011 to September 2023. We recorded demographics, medical and surgical history, clinical symptoms, and treatment at time of ARM, ARM findings (resting pressure, push maneuver, rectal sensation, rectoanal inhibitory reflex [RAIR], and RAIR duration), and the final interpretation of colonic manometry (CM) if performed. We identified age and sex-matched control groups of children with FC. We included 24 children with TCS (50% female) who had ARM testing (median age at ARM 6.0 years, interquartile range 4.0-11.8 years). All children had constipation at time of ARM. Nineteen children had detethering surgery before ARM was performed. No significant differences in ARM parameters were found between children who had detethering surgery before ARM and children with FC. Among the 24 children, 14 also had a CM performed (13/14 after detethering surgery). No significant differences in colonic motility were found between children with a history of TCS and children with FC. Anorectal physiology and colonic motility are similar between children with a history of TCS and children with FC, suggesting that the underlying pathophysiology of defecatory disorders in children with and without history of TCS is similar.

Vestibular prepulse inhibition of the human blink reflex

ObjectiveAuditory and somatosensory prepulses are commonly used to assess prepulse inhibition (PPI). The effect of a vestibular prepulse upon blink reflex excitability has not been hitherto assessed. MethodsTwenty-two healthy subjects and two patients with bilateral peripheral vestibular failure took part in the study. Whole body yaw rotation in the dark provided a vestibular inertial prepulse. Blink reflex was electrically evoked after the end of the rotation. The amplitude of R1 and the area-under-the-curve (area) of the blink reflex R2 and R2c responses were recorded and analysed. ResultsA vestibular prepulse inhibited the R2 (p < 0.001) and R2c area (p < 0.05). Increasing the angular acceleration did not increase the R2 and R2c inhibition (p > 0.05). Voluntary suppression of the vestibulo-ocular reflex did not affect the magnitude of inhibition (p > 0.05). Patients with peripheral vestibular failure did not show any inhibition. ConclusionsOur data support a vestibular gating mechanism in humans. SignificanceThe main brainstem nucleus mediating PPI – the pedunculopontine nucleus (PPN) – is heavily vestibular responsive, which is consistent with our findings of a vestibular-mediated PPI. Our technique may be used to interrogate the fidelity of brain circuits mediating vestibular-related PPN functions. Given the PPN’s importance in human postural control, our technique may also provide a neurophysiological biomarker of balance.

Positional Regulation, Sucking Reflex and Incidence When Given Nutrition Through OGT in High-Risk Infants with Low Birth Weight Infants in the Nicu Room: A Case Study of Waled Hospital

High-risk babies are babies born at 32 – 36 weeks of gestation/prematurely, babies whose mothers suffer from Diabetes Mellitus, babies with a history of apnea, babies with seizures, sepsis, asphyxia, babies with bleeding disorders or breathing problems. Problems that often arise in cases of LBW babies include unstable body temperature, breathing problems, digestive and nutritional disorders, liver immaturity, anaemia, intraventricular bleeding, seizures, infections, hypoglycemia, hyperglycemia and hypocalcemia. This study aims to provide nursing care to babies at high risk in the Nicu Room at Waled Hospital, Cirebon Regency, on 27 December 2023. Examination of the sucking reflex is recommended as a screening that shows intact motor neuron function in neonates. The sucking reflex is well-developed in normal babies and is coordinated with breathing. Inhibition of the sucking reflex in the first hours of life will affect the ability to suck at the beginning of life and will directly hinder the nutritional intake received by the baby. Arranging sleeping positions for newborn babies is the role of the neonatal nurse in providing routine daily care. Positioning, especially for premature babies, is not easy. Positioning errors can result in changes in physiological status (increased respiratory rate, pulse frequency, and decreased oxygen saturation), disturbed comfort and quality of sleep, drinking intolerance, hip joint deformity, and bleeding in the brain. The issues affecting all three clients have not been resolved. However, interventions such as positioning, assessing sucking reflexes in high-risk babies, and providing nutrition through OGT are ongoing, with efforts to set the supine sleep position during enteral nutrition. While the problems faced by the high-risk infants in this study are not yet resolved, ongoing nursing interventions are crucial in managing their care. Continued attention to proper positioning, monitoring of sucking reflexes, and nutritional support through OGT is vital for improving the health outcomes of these vulnerable infants.

Evaluation of the Effect of Age on the Contralateral Acoustic Reflex Suppression Test in Individuals With Normal Hearing.

The aim of this study is to investigate the age-related changes of the Contralateral Acoustic Reflex Suppression (CARS) test in individuals with normal hearing and to provide age-related normal values. The study included 66 individuals aged 18-65 years. The participants were divided into three age groups, respectively, 18-30 years, 31-45 years, and 46-65 years. Acoustic reflex threshold and acoustic reflex amplitude measurements were performed at frequencies of 500, 1000, and 2000 Hz in the presence and absence of suppressive noise from the contralateral ear. In the comparison of suppression amounts according to age groups, the highest suppression amount at all frequencies was observed in the 18-30 years age group. It is known that changes in the function of the efferent hearing system occur due to aging. In the CARS test, a decrease in the amount of suppression produced by the efferent system has been observed due to aging.

Quadriceps Activation After Anterior Cruciate Ligament Reconstruction: The Early Bird Gets the Worm!

Arthrogenic Muscle Inhibition (AMI) is a phenomenon observed in individuals with joint injury or pathology, characterized by a reflexive inhibition of surrounding musculature, altered neuromuscular control, and compromised functional performance. After anterior cruciate ligament reconstruction (ACLR) one of the most obvious consequences of AMI is the lack of quadriceps activation and strength. Understanding the underlying mechanisms of AMI is crucial for developing effective therapeutic interventions. The surgical procedure needed to reconstruct the ACL has biochemical et physiological consequences such as inflammation, pain, and altered proprioception. These alterations contribute to the development of AMI. Therapeutic interventions aimed at addressing AMI encompass a multidimensional approach targeting pain reduction, inflammation management, proprioceptive training, and quadriceps activation. Early management focusing on pain modulation through modalities like ice, compression, and pharmacological agents help mitigate the inflammatory response and alleviate pain, thereby reducing the reflexive inhibition of quadriceps. Quadriceps activation techniques such as neuromuscular electrical stimulation (NMES) and biofeedback training aid in overcoming muscle inhibition and restoring muscle strength. NMES elicits muscle contractions through electrical stimulation, bypassing the inhibitory mechanisms associated with AMI, thus facilitating muscle activation and strength gains. Comprehensive rehabilitation programs tailored to individual needs and stage of recovery are essential for optimizing outcomes in AMI. The objective of this clinical viewpoint is to delineate the significance of adopting a multimodal approach for the effective management of AMI, emphasizing the integration of pain modulation, proprioceptive training, muscle activation techniques, and manual therapy interventions. Highlighting the critical role of early intervention and targeted rehabilitation programs, this article aims to underscore their importance in restoring optimal function and mitigating long-term complications associated with AMI.

A Prediction Rule for the Dystonic Spread of Blepharospasm: A 4-Year Prospective Cohort Study.

Blepharospasm (BSP), focal dystonia with the highest risk of spread, lacks clear understanding of early spreading risk factors and objective prognostic indicators. We aimed to identify these risk factors through clinical and electrophysiological assessments, and to establish a predictive model for dystonic spread in BSP. We prospectively followed BSP patients for 4 years, collecting data on dystonic spread, and conducting electrophysiological evaluations. The blink reflex, masseter inhibitory reflex, and trigeminal somatosensory evoked potential were assessed. Univariable and multivariable Cox proportional hazard regression models were used to assess clinical characteristics associated with BSP dystonic spread. A predictive model was constructed using a nomogram, and performance of the model was evaluated using the area under the receiver operating characteristic curve. A total of 136 enrolled participants (mean age 56.34 years) completed a 4-year follow-up. Among them, 62 patients (45.6%) showed spread to other body regions. Multivariable Cox regression analysis showed that a high Hamilton Anxiety Scale score (hazard ratio 1.19, 95% confidence interval 1.13-1.25, p < 0.001), prolonged trigeminal somatosensory evoked potential mandibular branch P1-N2 peak interval (hazard ratio 1.11, 95% confidence interval 1.02-1.21, p = 0.017), and elevated trigeminal somatosensory evoked potential mandibular branch P1-N2 peak amplitude (hazard ratio 1.26, 95% confidence interval 1.12-1.41, p < 0.001) were independent risk factors for BSP dystonic spread within 4 years. Combining these factors, the predictive models demonstrated excellent discriminative ability, with the receiver operating characteristic curve score being 0.797, 0.790, 0.847, and 0.820 at 1, 2, 3 and 4 years after enrollment, respectively. We established a predictive model with significant value for anticipating dystonic spread in BSP, offering crucial evidence. These findings contribute essential insights into the early clinical identification of the development and evolution of BSP diseases. ANN NEUROL 2024.

Relation between the internal anal sphincter and defecation disorders in patients with anorectal malformations.

To investigate associations between the rectoanal inhibitory reflex (RAIR), type of congenital anorectal malformations (ARMs), type of operation that patients with ARM had undergone, and objectively measured fecal incontinence and defecation problems. We retrospectively included 69 pediatric patients with ARM. All underwent anorectal function tests at the University Medical Center of Groningen during the last 10 years. We assessed anorectal physiology using the Rome IV criteria and anorectal function tests. We found the reflex in 67% of patients and all types of ARMs. All patients who had not been operated on, and those who had undergone less extensive surgery possessed the reflex. In contrast, patients who underwent posterior sagittal anorectoplasty, 44% possessed it. We found no difference between mean rectal volumes in patients with and without the reflex (251 vs. 325 mL, respectively, p = 0.266). We found that over time, patients without the reflex seemed to develop significantly higher rectal volumes than patients who had it. We did not find a significant difference between the reflex and fecal incontinence; however, it seems that the absence of the reflex, resting anal sphincter pressure, and fecal incontinence are related. The RAIR seems present in patients with ARM irrespective of their malformation type. Corrective surgery, however, may impair this reflex. Seemingly, its absence results in constipation with enlarged rectal volumes and fecal incontinence. Every effort should be made to preserve this reflex during surgery and to use extensive surgical procedures as sparingly as possible.

Testing in functional constipation-What's new and what works.

Constipation is among the most common symptoms prompting a consultation with a paediatric gastroenterologist. While most patients will respond to lifestyle and dietary changes and conventional therapy, some may require diagnostic studies. To review the diagnostics studies used to evaluate children with functional constipation. There is no evidence to support the routine use of abdominal X-rays in the evaluation of paediatric constipation. Colon transit by radiopaque markers (ROM) should be indicated when medical history does not match clinical findings, to guide colon manometry (CM) performance and to discriminate between faecal incontinence from functional constipation and non-retentive faecal incontinence. Colon scintigraphy may be useful as an alternative to ROM. Lumbar spine MRI may be indicated to evaluate for spinal abnormalities. The role of defecography has not been properly evaluated in children. Anorectal manometry in children is indicated primarily to evaluate anal resting pressure, presence and quality of the recto-anal inhibitory reflex and simulated defecation manoeuvres. The CM is indicated to guide surgical interventions after failing medical therapy. The goal of these studies is to identify treatable causes of constipation. Most of these studies are designed to evaluate anatomy, transit and/or colon/rectum motility function and are primarily indicated in those who fail to respond to conventional therapy.

Heteronymous feedback from quadriceps onto soleus in stroke survivors.

Recent findings suggest increased excitatory heteronymous feedback from quadriceps onto soleus may contribute to abnormal coactivation of knee and ankle extensors after stroke. However, there is lack of consensus on whether persons post-stroke exhibit altered heteronymous reflexes and, when present, the origin of increased excitation (i.e. increased excitation alone and/or decreased inhibition). This study examined heteronymous excitation and inhibition from quadriceps onto soleus in paretic, nonparetic, and age-matched control limbs to determine whether increased excitation was due to excitatory and/or reduced inhibitory reflex circuits. A secondary purpose was to examine whether heteronymous reflex magnitudes were related to clinical measures of lower limb recovery, walking-speed, and dynamic balance. Heteronymous excitation and inhibition from quadriceps onto soleus were examined in fourteen persons post-stroke and fourteen age-matched unimpaired participants. Heteronymous feedback was elicited by femoral nerve and quadriceps muscle stimulation in separate trials while participants tonically activated soleus at 20% max. Fugl-Myer assessment of lower extremity, 10-meter walk test, and Mini-BESTest were assessed in stroke survivors. Heteronymous excitation and inhibition onsets, durations, and magnitudes were not different between paretic, nonparetic or age-matched unimpaired limbs. Quadriceps stimulation elicited excitation that was half the magnitude of femoral nerve stimulation. Femoral nerve elicited paretic limb heteronymous excitation was positively correlated with walking speed but did not reach significance because only a subset of paretic limbs exhibited excitation (n = 8, Spearman r = 0.69, P = 0.058). Heteronymous feedback from quadriceps onto soleus assessed in a seated posture was not impaired in persons post-stroke. Despite being unable to identify whether reduced inhibition contributes to abnormal excitation reported in prior studies, our results indicate quadriceps stimulation may allow a better estimate of heteronymous inhibition in those that exhibit exaggerated excitation. Heteronymous excitation magnitude in the paretic limb was positively correlated with self-selected walking speed suggesting paretic limb excitation at the higher end of a normal range may facilitate walking ability after stroke. Future studies are needed to identify whether heteronymous feedback from Q onto SOL is altered after stroke in upright postures and during motor tasks as a necessary next step to identify mechanisms underlying motor impairment.

Physiology of lower gastrointestinal tract.

The lower gastrointestinal (GI) tract, formed from the midgut and hindgut, encompasses the colon, rectum and anal canal. The aim of this review is to provide an overview of the anatomy and physiology of the lower GI tract. Literature review on anatomy and physiology of the lower GI tract, including normal motility and phases of defecation. It derives its blood supply from the superior and inferior mesenteric arteries while it is innervated by the extrinsic autonomic (the thoracolumbar and sacral nerves) and the intrinsic enteric nervous system. The colon has four layers: mucosa, submucosa, muscularis externa and serosa. The anal canal ends in the internal and external anal sphincters (EASs) involved in continence and defecation. The lower GI tract is predominantly involved in digestion, absorption, defecation and protection. Defecation is a complex process that requires inter-neural (enteric and autonomic nervous systems), neurohormonal and neuromuscular coordination. It has four phases which include basal, pre-expulsive, expulsive and end phase. High-propagating contractions in the colon propel stool to the rectum leading to rectal distention and the recruitment of the recto-anal inhibitory reflex. Once able, the EAS, under full conscious control, is then relaxed allowing stool to be evacuated. Other defecation reflexes include the gastrocolic, gastroileal and coloanal reflexes. Recent advances provide novel techniques to investigate motility patterns including high-resolution manometry protocols with automated assessments, magnetic resonance imaging techniques for defecography, wireless motility capsules and fecobionics.

The role of the Ventral Nucleus of the Trapezoid Body in the auditory prepulse inhibition of the acoustic startle reflex

Cholinergic signaling is essential to mediate the auditory prepulse inhibition (PPI), an operational measure of sensorimotor gating, that refers to the reduction of the acoustic startle reflex (ASR) when a low-intensity, non-startling acoustic stimulus (the prepulse) is presented just before the onset of the acoustic startle stimulus. The cochlear root neurons (CRNs) are the first cells of the ASR circuit to receive cholinergic inputs from non-olivocochlear neurons of the ventral nucleus of the trapezoid body (VNTB) and subsequently decrease their neuronal activity in response to auditory prepulses. Yet, the contribution of the VNTB-CRNs pathway to the mediation of PPI has not been fully elucidated. In this study, we used the immunotoxin anti-choline acetyltransferase (ChAT)-saporin as well as electrolytic lesions of the medial olivocochlear bundle to selectively eliminate cholinergic VNTB neurons, and then assessed the ASR and PPI paradigms. Retrograde track-tracing experiments were conducted to precisely determine the site of lesioning VNTB neurons projecting to the CRNs. Additionally, the effects of VNTB lesions and the integrity of the auditory pathway were evaluated via auditory brain responses tests, ChAT- and FOS-immunohistochemistry. Consequently, we established three experimental groups: 1) intact control rats (non-lesioned), 2) rats with bilateral lesions of the olivocochlear bundle (OCB-lesioned), and 3) rats with bilateral immunolesions affecting both the olivocochlear bundle and the VNTB (OCB/VNTB-lesioned). All experimental groups underwent ASR and PPI tests at several interstimulus intervals before the lesion and 7, 14, and 21 days after it. Our results show that the ASR amplitude remained unaffected both before and after the lesion across all experimental groups, suggesting that the VNTB does not contribute to the ASR. The%PPI increased across the time points of evaluation in the control and OCB-lesioned groups but not in the OCB/VNTB-lesioned group. At the ISI of 50 ms, the OCB-lesioned group exhibited a significant increase in%PPI (p < 0.01), which did not occur in the OCB/VNTB-lesioned group. Therefore, the ablation of cholinergic non-olivocochlear neurons in the OCB/VNTB-lesioned group suggests that these neurons contribute to the mediation of auditory PPI at the 50 ms ISI through their cholinergic projections to CRNs. Our study strongly reinforces the notion that auditory PPI encompasses a complex mechanism of top-down cholinergic modulation, effectively attenuating the ASR across different interstimulus intervals within multiple pathways.

Well-Established and Traditional Use of Vegetal Extracts as an Approach to the "Deep Roots" of Cough.

Cough is a common presenting symptom for patients in a primary care setting and significantly impacts a patient's quality of life. Cough involves a complex reflex arc beginning with the stimulation of sensory nerves that function as cough receptors that stimulate the cough center in the brain. This "cough center" functions to receive these impulses and produce a cough by activating efferent nervous pathways to the diaphragm and laryngeal, thoracic, and abdominal musculature. Drugs that suppress the neural activity of cough are non-specific as those treatments are not directed toward pathogenic causes such as inflammation and oxidative stress. Moreover, they block a reflex called the watchdog of the lung and have a defense mechanism. Acute respiratory infections of the upper and lower airways most commonly cause acute cough. In contrast, the most common causes of chronic cough are upper airway cough syndrome, asthma, and gastroesophageal reflux disease, all associated with an inflammatory reaction at the level of the cough receptors. The use of natural compounds or herbal drugs such as carob syrup, dry blackcurrant extract, dry extract of caraway fruit, dry extract of ginger rhizome, dry extract of marshmallow root, and dry extract of ivy leaves, to name a few, not only have anti-inflammatory and antioxidant activity, but also act as antimicrobials, bronchial muscle relaxants, and increase gastric motility and empty. For these reasons, these natural substances are widely used to control cough at its deep roots (i.e., contrasting its causes and not inhibiting the arch reflex). With this approach, the lung watchdog is not put to sleep, as with peripheral or central inhibition of the cough reflex, and by contrasting the causes, we may control cough that viruses use at self-advantage to increase transmission.