Simple Reflex Research Articles

Apraisal of the diagnostic value of the gag reflex in patients with neurogenic oropharyngeal dysphagia

The gag reflex is a protection mechanism that prevents food and unwanted agents from entering the lower airways. It is usually part of the physical examination of swallowing to detect oropharyngeal dysphagia, but it is a potentially ambiguous sign. To evaluate the diagnostic value of the gag reflex in patients with neurogenic oropharyngeal dysphagia and adults without it. We conducted an analytical observational study in patients with neurogenic oropharyngeal dysphagia (cases) and patients without dysphagia (controls). We evaluated the absence or presence of the reflex bilaterally, by direct visualization, and adjusted it according to sex, age, and other interaction variables. We included 86 patients with neurogenic oropharyngeal dysphagia and 80 control subjects. The gag reflex on swallowing physical examination showed a positive relationship with the patients (right side: OR = 3.97; 95 % CI: 2.01-7.84; left side: OR = 4.84; 95 % CI: 2.41-9.72), but a negative association with the control group. In both groups, neither sex, nor age, nor other interaction variables modified the gag reflex. The gag reflex absence or presence does not confirm or exclude the existence of oropharyngeal dysphagia due to neurological and neuromuscular causes. Therefore, health professionals must not rely on this reflex. Clinicians must go beyond a simple reflex revision, even in neurological patients where it is supposed to be absent.

Evaluation of controllers for augmentative hip exoskeletons and their effects on metabolic cost of walking: explicit versus implicit synchronization.

Background: Efficient gait assistance by augmentative exoskeletons depends on reliable control strategies. While numerous control methods and their effects on the metabolic cost of walking have been explored in the literature, the use of different exoskeletons and dissimilar protocols limit direct comparisons. In this article, we present and compare two controllers for hip exoskeletons with different synchronization paradigms. Methods: The implicit-synchronization-based approach, termed the Simple Reflex Controller (SRC), determines the assistance as a function of the relative loading of the feet, resulting in an emerging torque profile continuously assisting extension during stance and flexion during swing. On the other hand, the Hip-Phase-based Torque profile controller (HPT) uses explicit synchronization and estimates the gait cycle percentage based on the hip angle, applying a predefined torque profile consisting of two shorter bursts of assistance during stance and swing. We tested the controllers with 23 naïve healthy participants walking on a treadmill at 4km ⋅ h-1, without any substantial familiarization. Results: Both controllers significantly reduced the metabolic rate compared to walking with the exoskeleton in passive mode, by 18.0% (SRC, p < 0.001) and 11.6% (HPT, p < 0.001). However, only the SRC led to a significant reduction compared to walking without the exoskeleton (8.8%, p = 0.004). The SRC also provided more mechanical power and led to bigger changes in the hip joint kinematics and walking cadence. Our analysis of mechanical powers based on a whole-body analysis suggested a reduce in ankle push-off under this controller. There was a strong correlation (Pearson's r = 0.778, p < 0.001) between the metabolic savings achieved by each participant with the two controllers. Conclusion: The extended assistance duration provided by the implicitly synchronized SRC enabled greater metabolic reductions compared to the more targeted assistance of the explicitly synchronized HPT. Despite the different assistance profiles and metabolic outcomes, the correlation between the metabolic reductions with the two controllers suggests a difference in individual responsiveness to assistance, prompting more investigations to explore the person-specific factors affecting assistance receptivity.

Learning and Neural Activity: Beyond Localization

Learning is classified into two types: "classical conditioning," which modifies simple reflexes, and "operant conditioning," which modifies complex voluntary behaviors. The neural circuits underlying these two types differ significantly. During the learning process of operant conditioning tasks, various changes in firing rate and firing synchrony of neurons can be observed across multiple brain regions. Additionally, neuronal firing rate and synchrony in several brain regions can be voluntarily controlled through operant conditioning. Consequently, it is evident that neurons in widespread brain regions have the potential for plastic changes to facilitate learning. It may be suggested that the learning of complex voluntary behaviors is underlined by widespread dynamic changes in neural activity and is not restricted to only a few brain regions.

Impaired cerebellar plasticity hypersensitizes sensory reflexes in SCN2A-associated ASD

Children diagnosed with autism spectrum disorder (ASD) commonly present with sensory hypersensitivity or abnormally strong reactions to sensory stimuli. Such hypersensitivity can be overwhelming, causing high levels of distress that contribute markedly to the negative aspects of the disorder. Here, we identify a mechanism that underlies hypersensitivity in a sensorimotor reflex found to be altered in humans and in mice with loss of function in the ASD risk-factor gene SCN2A. The cerebellum-dependent vestibulo-ocular reflex (VOR), which helps maintain one's gaze during movement, was hypersensitized due to deficits in cerebellar synaptic plasticity. Heterozygous loss of SCN2A-encoded NaV1.2 sodium channels in granule cells impaired high-frequency transmission to Purkinje cells and long-term potentiation, a form of synaptic plasticity important for modulating VOR gain. VOR plasticity could be rescued in mice via a CRISPR-activator approach that increases Scn2a expression, demonstrating that evaluation of a simple reflex can be used to assess and quantify successful therapeutic intervention.

Network architecture of intrinsic connectivity in a mammalian spinal cord (the central nervous system’s caudal sector)

The vertebrate spinal cord (SP) is the long, thin extension of the brain forming the central nervous system's caudal sector. Functionally, the SP directly mediates motor and somatic sensory interactions with most parts of the body except the face, and it is the preferred model for analyzing relatively simple reflex behaviors. Here, we analyze the organization of axonal connections between the 50 gray matter regions forming the bilaterally symmetric rat SP. The assembled dataset suggests that there are about 385 of a possible 2,450 connections between the 50 regions for a connection density of 15.7%. Multiresolution consensus cluster analysis reveals a hierarchy of structure-function subsystems in this neural network, with 4 subsystems at the top level and 12 at the bottom-level. The top-level subsystems include a) a bilateral subsystem related most clearly to somatic and autonomic motor functions and centered in the ventral horn and intermediate zone; b) a bilateral subsystem associated with general somatosensory functions and centered in the base, neck, and head of the dorsal horn; and c) a pair of unilateral, bilaterally symmetric subsystems associated with nociceptive information processing and occupying the apex of the dorsal horn. The intrinsic SP network displayed no hubs, rich club, or small-world attributes, which are common measures of global functionality. Advantages and limitations of our methodology are discussed in some detail. The present work is part of a comprehensive project to assemble and analyze the neurome of a mammalian nervous system and its interactions with the body.

Примитивные рефлексы спинально-стволового уровня и их реабилитационное значение у постинсультных больных: краткое сообщение

INTRODUCTION. Primitive reflexes of the spinal-brainstem level (defensive reflexes, support reactions, cervical and vestibular tonic reflexes) can often be observed in the first days after a stroke. In clinical neurology, they are used for topical diagnosis and serve as an indicator of the severity of damage to the central nervous system. Their rehabilitation value has not been sufficiently studied. AIM. Based on literature data, to study the features of primitive spinal-brainstem automatisms in post-stroke patients, and to evaluate the possibility of their use to optimize rehabilitation methods (kinesitherapy). RESULTS. Simple protective reflexes are suitable for awakening elementary motor activity in one of the paralyzed limbs, and complex ones are suitable for stimulating static-locomotor reactions in the arm and leg on the side of hemiparesis. Support reactions are a reliable tool for awakening both flexion movements and for restoring the support ability of paretic limbs. They should be considered when treating with positioning using positioning, splints, and orthoses. Cervical and vestibular tonic reflexes are suitable for stimulating motor activity on the side of hemiparesis, as well as for suppressing pyramidal spasticity. CONCLUSION. Thus, all studied primitive reflexes of the spinal-brainstem level have significant rehabilitation potential. Their use is most justified to facilitate flexion-extension movements in paretic limbs. The better the rehabilitologist is familiar with the characteristics of the patient’s reflex activity, the more opportunities he has for conducting a “dialogue” with paretic muscles and the more effective the rehabilitation treatment will be. KEYWORDS: protective reflex, support reaction reflex, cervical tonic reflexes, vestibular tonic reflexes, ehabilitation

Electrochemical exploration of cobalt sulfide nanoparticles synthesis using cobalt diethyldithiocarbamate as single source precursor for hybrid supercapacitor device

The cobalt sulfide (Co 9 S 8 ) nanoparticles (NPs) have been synthesized by the solvothermal techniques by utilizing Cobalt diethyldithiocarbamate (Co[DTC] 2 ) as single-source precursor and hexadecylamine (HDA) as shape directing agent. As-prepared Co 9 S 8 NPs were characterized with structural, morphological, thermal, Spectroscopic and surface analysis using PXRD, TEM, SEM-EDS, TG/DTA, FTIR, Raman and XPS studies respectively. The electrochemical performances were investigated by galvanostatic charge-discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) analysis with Co 9 S 8 NPs modified working electrode. The Co 9 S 8 NPs modified electrode delivered excellent specific capacitances of 502 Fg −1 at current densities of 1 Ag −1 . The capacitance retention of Co 9 S 8 was found to be 87 % over the examination even after 7000 cycles. Furthermore, a hybrid supercapacitor (HSC) device assembled with cathode and anode materials delivers a high energy density of 15.47 Wh kg −1 with power density of 1274.9 W kg −1 . • Co 9 S 8 nanoparticles have been successfully synthesized by simple solvothermal reflex method. • PXRD and SEM exhibit the cubic crystalline structure and spherical-like morphology for Co 9 S 8 nanoparticles. • Co 9 S 8 electrode material exhibits Faradic pseudo capacitive behaviour. • An enhanced high specific capacitance of 502 Fg −1 and current density of 1 Ag −1 . • The Co 9 S 8 electrode material exhibits 87 % energy retention in cyclic test after 7000 cycles.

Second-order associative memory circuit hardware implemented by the evolution from battery-like capacitance to resistive switching memory

SummaryMemristor-based Pavlov associative memory circuit presented today only realizes the simple condition reflex process. The secondary condition reflex endows the simple condition reflex process with more bionic, but it is only demonstrated in design and involves the large number of redundant circuits. A FeOx-based memristor exhibits an evolution process from battery-like capacitance (BLC) state to resistive switching (RS) memory as the I-V sweeping increase. The BLC is triggered by the active metal ion and hydroxide ion originated from water molecule splitting at different interfaces, while the RS memory behavior is dominated by the diffusion and migration of ion in the FeOx switching function layer. The evolution processes share the nearly same biophysical mechanism with the second-order conditioning. It enables a hardware-implemented second-order associative memory circuit to be feasible and simple. This work provides a novel path to realize the associative memory circuit with the second-order conditioning at hardware level.

On the Distribution of Reflexive Anaphors and Logophoric Anaphors in Balinese

The central claim of this paper is that reflexive anaphors and logophoric anaphors in Balinese share the same forms. It is shown that Balinese possesses simple and complex reflexives. Only complex reflexives participate in the logophoric environment. Importantly it is claimed that the logophoric use of the reflexive anaphor occurs in a clausal complement of the verbs of communication and other verbs denoting a general state of consciousness. The logophor can appear in the subject or object position of the embedded clause while the reflexive use of the anaphor is only limited to occurring in a single clause and is restricted to occupying the object position, either the object of a verb or the object of a preposition. The characteristic differences in the distribution between the two are reflected in a syntactic domain having to do with passivization in that logophoric constructions allow it while reflexive constructions completely ban it. In addition, logophoricity may characterize an operation where there is a mismatch in the agreement between the logophor and its targeted antecedent whereas in reflexivity there must be an agreement in the phi-features between the binder and the bindee.

Neural Reflex Networks for Automating Quadcopter Drone Obstacle Avoidance

The physically modelled neural and nervous networks pioneered more than two decades ago by Mark Tilden, E. A. Rietman and collaborators, M. Ashkenazi et al. have proven to be a robust and interesting way to obtain powerful emergent behavior by utilizing neuromimetic circuitry. Using a physical representation of biologic neurons, both motor (NU) and cortical (NV) these structures mimic simple reflex arcs present in a large number of evolved organisms. The simple circuits using logic gate oscillators wired as integrators or pulse delay loops with sensors coupled as current injectors or variable resistors of different types demonstrated unexpected emergent „survival” behaviors when connected in chains or loops of several neurons. Mark Tilden calls the simplest functional unit of such looped structures „bicores”-as two neurons linked together in a loop already generate meaningful behavior when their inputs are linked to appropriate sensors. These powerful neuromimetic machines allow for a robust implementation of automated responses in autonomous or semi-autonomous robots. Quadcopters are a very good target for neural network control/stabilization because of their unique flight dynamics and normal control procedures. Obstacle avoidance and stabilization are simple tasks for a well-tuned physical neural network.

\u2018Falling heads\u2019: investigating reflexive responses to head\u2013neck perturbations

BackgroundReflexive responses to head–neck perturbations affect the injury risk in many different situations ranging from sports-related impact to car accident scenarios. Although several experiments have been conducted to investigate these head–neck responses to various perturbations, it is still unclear why and how individuals react differently and what the implications of these different responses across subjects on the potential injuries might be. Therefore, we see a need for both experimental data and biophysically valid computational Human Body Models with bio-inspired muscle control strategies to understand individual reflex responses better.MethodsTo address this issue, we conducted perturbation experiments of the head–neck complex and used this data to examine control strategies in a simulation model. In the experiments, which we call ’falling heads’ experiments, volunteers were placed in a supine and a prone position on a table with an additional trapdoor supporting the head. This trapdoor was suddenly released, leading to a free-fall movement of the head until reflexive responses of muscles stopped the downwards movement.ResultsWe analysed the kinematic, neuronal and dynamic responses for all individuals and show their differences for separate age and sex groups. We show that these results can be used to validate two simple reflex controllers which are able to predict human biophysical movement and modulate the response necessary to represent a large variability of participants.ConclusionsWe present characteristic parameters such as joint stiffness, peak accelerations and latency times. Based on this data, we show that there is a large difference in the individual reflexive responses between participants. Furthermore, we show that the perturbation direction (supine vs. prone) significantly influences the measured kinematic quantities. Finally, ’falling heads’ experiments data are provided open-source to be used as a benchmark test to compare different muscle control strategies and to validate existing active Human Body Models directly.

Is my food safe? – AI-based classification of lentil flour samples with trace levels of gluten or nuts

An artificial intelligence-based method to rapidly detect adulterated lentil flour in real time is presented. Mathematical models based on convolutional neural networks and transfer learning (viz., ResNet34) have been trained to identify lentil flour samples that contain trace levels of wheat (gluten) or pistachios (nuts), aiding two relevant populations (people with celiac disease and with nut allergies, respectively). The technique is based on the analysis of photographs taken by a simple reflex camera and further classification into groups assigned to adulterant type and amount (up to 50 ppm). Two different algorithms were trained, one per adulterant, using a total of 2200 images for each neural network. Using blind sets of data (10% of the collected images; initially and randomly separated) to evaluate the performance of the models led to strong performances, as 99.1% of lentil flour samples containing ground pistachio were correctly classified, while 96.4% accuracy was reached to classify the samples containing wheat flour.

Newborns modulate their crawling in response to their native language but not another language.

Human newborns can propel themselves to their mother's breast when positioned skin to skin on her abdomen just after birth. For decades, researchers have considered this primitive crawling behavior a spinal reflex, immune to supra spinal control. However, recent research suggests that neonatal crawling is already responsive to visual and olfactory stimuli processed at a supra spinal level. Here we report that a few hours post birth, French newborns can also modulate their crawling in response to their native language - a source of information that is processed supra-spinally. The crawling patterns of 23 French-born newborns were recorded on video and via an infrared motion capture system during two randomly ordered 2-min trials. The newborns were secured on a mini skateboard to facilitate arm and leg movements during their crawling propulsion. They heard a repetitive sequence of the same sentences either in French, their native language, or in English, a rhythmically different and hence discriminable unfamiliar language, on each trial. In French, compared to English, crawling was enhanced, with significantly more arm and leg steps and significantly more and larger trunk rotations in the cephalo-caudal axis. Moreover, newborns rotated their heads and trunk toward the appropriate loud speaker when hearing French but not English. These preliminary findings suggest that newborn crawling is not a simple stereotyped reflex under spinal control, but a complex pattern that can be modulated in response to higher-order, supra-spinally processed stimuli. The findings open fascinating questions about the range of stimuli to which newborn crawling is responsive.

Said the Hooker to the Thief

Said the Hooker to the Thief

Enteric Control of the Sympathetic Nervous System.

The autonomic nervous system that regulates the gut is divided into sympathetic (SNS), parasympathetic (PNS), and enteric nervous systems (ENS). They inhibit, permit, and coordinate gastrointestinal motility, respectively. A fourth pathway, "extrinsic sensory neurons," connect gut to the central nervous system, mediating sensation. The ENS resides within the gut wall and its activities are critical for life; ENS failure to populate the gut in development is lethal without intervention."Viscerofugal neurons" are a distinctive class of enteric neurons, being the only type that escapes the gut wall. They form a unique circuit: their axons project out of the gut wall and activate sympathetic neurons, which then project back to the gut, and inhibit gut movements.For 80 years viscerofugal/sympathetic circuits were thought to have a restricted role, mediating simple sensory-motor reflexes. New data shows viscerofugal and sympathetic neurons behaving unexpectedly, compelling a re-evaluation of these circuits: both viscerofugal and sympathetic neurons transmit higher order, synchronized firing patterns that originate within the ENS. This identifies them as driving long-range motility control between different gut regions.There is need for gut motor control over distances beyond the range of ENS circuits, yet no mechanism has been identified to date. The entero-sympathetic circuits are ideally suited to meet this need. Here we provide an overview of the structure and functions of these peripheral sympathetic circuits, including new data showing the firing patterns generated by enteric networks can transmit through sympathetic neurons.

The Pupillary Light Reflex as a Biomarker of Concussion.

The size of our pupils changes continuously in response to variations in ambient light levels, a process known as the pupillary light reflex (PLR). The PLR is not a simple reflex as its function is modulated by cognitive brain function and any long-term changes in brain function secondary to injury should cause a change in the parameters of the PLR. We performed a retrospective clinical review of the PLR of our patients using the BrightLamp Reflex iPhone app. The PLR variables of latency, maximum pupil diameter (MaxPD), minimum pupil diameter (MinPD), maximum constriction velocity (MCV), and the 75% recovery time (75% PRT) were associated with significant differences between subjects who had suffered a concussion and those that had not. There were also significant differences in PLR metrics over the life span and between genders and those subjects with and without symptoms. The differences in PLR metrics are modulated not only by concussion history but also by gender and whether or not the person has symptoms associated with a head injury. A concussive injury to the brain is associated with changes in the PLR that persist over the life span, representing biomarkers that might be used in clinical diagnosis, treatment, and decision making.

The pupil responds spontaneously to perceived numerosity

Although luminance is the main determinant of pupil size, the amplitude of the pupillary light response is also modulated by stimulus appearance and attention. Here we ask whether perceived numerosity modulates the pupillary light response. Participants passively observed arrays of black or white dots of matched physical luminance but different physical or illusory numerosity. In half the patterns, pairs of dots were connected by lines to create dumbbell-like shapes, inducing an illusory underestimation of perceived numerosity; in the other half, connectors were either displaced or removed. Constriction to white arrays and dilation to black were stronger for patterns with higher perceived numerosity, either physical or illusory, with the strength of the pupillary light response scaling with the perceived numerosity of the arrays. Our results show that even without an explicit task, numerosity modulates a simple automatic reflex, suggesting that numerosity is a spontaneously encoded visual feature.

0 trigemino-vagal reflex

Reflexology is the most fruitful part of neurology. With the accumulation of data in this area and the establishment of new principles and laws, our knowledge about the functions of the brain deepens, starting with simple reflexes of the medullae spinalis (Marschal ) and ending with complex reflexes of the cerebral hemispheres (combined, inhibited reflexes).

Reflex theory, cautionary tale: misleading simplicity in early neuroscience

This paper takes an integrated history and philosophy of science approach to the topic of "simplicity out of complexity". The reflex theory was a framework within early twentieth century psychology and neuroscience which aimed to decompose complex behaviours and neural responses into simple reflexes. It was controversial in its time, and did not live up to its own theoretical and empirical ambitions. Examination of this episode poses important questions about the limitations of simplifying strategies, and the relationship between simplification and the engineering approach to biology.

Sleep and conditioning of the siphon withdrawal reflex in Aplysia.

Sleep is essential for memory consolidation after learning as shown in mammals and invertebrates such as bees and flies. Aplysia californica displays sleep, and sleep in this mollusk was also found to support memory for an operant conditioning task. Here, we investigated whether sleep in Aplysia is also required for memory consolidation in a simpler type of learning, i.e. the conditioning of the siphon withdrawal reflex. Two groups of animals (Wake, Sleep, each n=11) were conditioned on the siphon withdrawal reflex, with the training following a classical conditioning procedure where an electrical tail shock served as the unconditioned stimulus (US) and a tactile stimulus to the siphon as the conditioned stimulus (CS). Responses to the CS were tested before (pre-test), and 24 and 48 h after training. While Wake animals remained awake for 6 h after training, Sleep animals had undisturbed sleep. The 24 h test in both groups was combined with extinction training, i.e. the extended presentation of the CS alone over two blocks. At the 24 h test, siphon withdrawal duration in response to the CS was distinctly enhanced in both Sleep and Wake groups with no significant difference between groups, consistent with the view that consolidation of a simple conditioned reflex response does not require post-training sleep. Surprisingly, extinction training did not reverse the enhancement of responses to the CS. On the contrary, at the 48 h test, withdrawal duration in response to the CS was even further enhanced across both groups. This suggests that processes of sensitization, an even simpler non-associative type of learning, contributed to the withdrawal responses. Our study provides evidence for the hypothesis that sleep preferentially benefits consolidation of more complex learning paradigms than conditioning of simple reflexes.