Higher reflexes

The term reflex is used in a broad sense. Reflexes having a drive component are denoted as higher. Four types of higher reflexes are distinguished: avoidance, escape approach and consummately. Each of these reflexes has a different drive component. The result of the reflex is a removal of the corresponding drive. For this purpose three different strategies are used. Complex higher reflexes are usually programmed and occur frequently in a chain form. A given function of an organism is performed by a system of reflexes controlled by one or more drives.     

Interaction of dominant focus and conditional reflex as a functional unit of behavior organization

The interaction of two fundamental phenomena—the dominant focus and the conditional reflex—discovered and introduced by A. A. Ukhtomsky and I. P. Pavlov lay at the basis of behavior. According to E. A. Asratyan, the backward conditioned connection is a specialized dominant focus in the functional structure of the consolidated conditional reflex. It makes the behavior goal-directed and active. The dominant focus and conditioned reflex play the same role in the adaptive behavior of the individual as does variability and selection in the process of evolutional adaptation. That is why it is impossible to agree with Popper and Eccles that hypothesis theory has to replace Pavlov’s theory of the conditional reflex. Imprinting and psychonervous activity by images (I. S. Beritashvili) are two special exemplars of conditional reflexes after one coincidence. The so-called “elementary reasoning activity of animals” (according to L. V. Krushinsky) is a kind of the instinctive inherited behavior.     

Stretch reflexes in the human masticatory muscles: a brief review and a new functional role

Stretch reflexes play a vital role in fine-tuning movements and in automatically maintaining posture. This article briefly reviews the operation of the stretch reflex in the human masticatory system. The conventional approach of stretching muscles in an open-loop manner has yielded much valuable information on the operation of this reflex. In particular, it has revealed that stretching the jaw-closing muscles evokes a reflex response with two major components. The short-latency reflex is favoured when stretches are brisk, but slower stretches evoke an additional long-latency component. In the hand muscles, the long-latency response is transcortical: in the masticatory muscles, it is not. In addition to its role in servo-control of muscle length during chewing, the stretch reflex in the jaw-closing muscles maintains the vertical position of the mandible during vigorous head movements such as those that occur during running, jumping, hopping and other vigorous whole-body movements in which the head moves briskly up and down. This is an interesting model system in which to investigate stretch reflexes with natural stimuli under unrestrained, physiological conditions.     

Measurement of muscle reflex time in radicular disorders of the lumbosacral region]

The results of studies performed by the authors show that time measurements of proprioceptive muscular reflexes (triceps surae and tibialis posterior reflexes) may be considered a valuable addition to methods of topical diagnosis of radicular disturbances in the lumbosacral region. The reflexes were tested in twenty normal subjects. There were found an intraindividual constancy of the respective reflex time with a maximum deviation of 2 ms as well as a lateral variability up to 1.3 ms. Radicular compressions resulted in an increase in reflex time by 2 to 66 ms or failure of the reflex potential to be recorded. The pathological cases were compared with clinical and neurological studies, positive myelographies using radiopaque substances, and results of surgical operations. Compared with the results of surgical operations, changes in reflex time indicated damage to the reflex arc in ninety percent of the cases.     

Sensitization and aversive conditioning: Effects on the startle reflex and electrodermal responding

Animal data suggest that shock sensitization as well as aversive learning potentiates the acoustic startle reflex. The present experiment tested, whether this shock sensitization also occurs in human subjects and whether it precedes aversive conditioning. Sixty subjects viewed—prior to conditioning—a series of slides of different emotional contents including the to be conditioned stimuli (CSs). Afterwards, the experimenter attached the shock electrodes and initiated shock exposure. Then, subjects were randomly assigned to view a series of two slides, each for eight acquisition trials in which one slide was followed by a shock. Subsequently, extinction trials (12 for each slide) were administered. During preconditioning, acquisition, and extinction, startle probes occurred unpredictably during and between slide viewing. Preconditioning data replicated previous results by Lang and his associates, showing that the startle response magnitude is directly related to the affective valence induced by the slides. Shock exposure strongly facilitated the startle reflex magnitude. This shock sensitization was absent for the skin conductance response. Course of learning also varied for both response systems. The data suggest that startle reflex potentiation indexes the acquisition of an avoidance disposition, which is preceded by a general sensitization of the protective reflexes. Skin conductance learning follows arousal changes and is modulated by cognitive processes.     

惊跳反射的生理心理机制

惊跳反射作为动物及人类在应对意外刺激或遇到险情时的一种避险保护反应,具有重要的生物学意义。以往的研究较多关注听觉惊跳反射,在反应指标上多采用眼部及面部表情肌的反应,如眨眼反射。惊跳反射的生理机制为突发性强刺激直接传向杏仁核的直接通路所致。惊跳反射增强的心理机制可能为致敏作用或恐惧性条件作用,而惊跳反射衰减的心理机制可能是适应、前脉冲抑制或愉快衰减。未来的研究应关注视觉惊跳反射,观察全身躯体姿势维持肌肉群的反应模式,并以先进设备对惊跳反射的信息加工脑机制进行深入的研究     

Complex form of instrumental behavior of dogs

A complex form of higher nervous activity, conditional reflex transswitching or switching, was elaborated in four dogs under conditions of unrestrained movements, freedom of reinforcement choice (food or water), place of reinforcement determined by situation factors as well as independent switching on of conditional stimuli. It was shown that motivated goal-directed behavior of the animals was determined by activation of forward and backward connections. The chains of instrumental conditioned reflexes forming in the final analysis the complex behavior are developed according to the “trialand-error” principle. In the instrumental conditioned reflexes there are two constantly coexisting types of mutually complementing conditioned connections of the signal with reinforcement—direct and indirect. In experiments with unrestrained conditions of animals and independent regulation of the experiment, one of the frequently encountered physiological mechanisms of generalization appears to be efferent and afferent generalization.     

Patterns of reflex action,their autonomic components,and their behavioral significance

This is a discussion of the evidence that autonomic system reflexes are invariably triggered by stimuli that evoke both simple and complex somatic reflexes. Stimuli not only initiate reverberatory activity but sequences of reinforcements from higher centers. Reflexes come in chains, one reaction triggering another. Reflex actions are patterned, and these patterns are appropriate to the behavioral requirement indicated by stimuli. Reciprocal action produces a powerful braking or stimulatory action. Coactivation or synergic action of autonomie “antagonists” also occurs and can effect a greater cardiac output in certain vascular reflexes than can sympathetic action alone. Coactivation of vagus and sympathetic fibers occuring in reflex action or resulting from stimulation of specific areas in the hypothalamus has a physiologic importance to attainment of maximal cardiac function. Finally, two additional suggestions are made: (1) that the rhythmic reflex feedback discharge of the vagus from the baroreceptors aids in maintaining the regularity of cardiac rhythm as by interaaction of oscillators and (2) that the autonomic system, due to its early and often conditioned response, can be determinative as well as modulatory and supportive of behavior.     

The role of the perioral reflex in lip motor control for speech.

The analysis of spinal and brainstem reflexes has been shown to be a useful method of quantifying the various inputs to motoneuron pools involved in voluntary motor control. This work is selectively reviewed as a background to a discussion of the role of the perioral reflex in lip motor control for speech. Data on the sensorimotor innervation of the lips and the static and dynamic properties of the perioral reflex are presented in support of the notions that (1) perioral reflex analysis provides a viable technique for analyzing brainstem excitability changes underlying lip muscle contraction for speech, and (2) the perioral reflex loop is an important functional element in lip motor control for speech.     

Influence of delayed muscle reflexes on spinal stability: Model-based predictions allow alternative interpretations of experimental data

Model-based calculations indicate that reflex delay and reflex gain are both important for spinal stability. Experimental results demonstrate that chronic low back pain is associated with delayed muscle reflex responses of trunk muscles. The aim of the present study was to analyze the influence of such time-delayed reflexes on the stability using a simple biomechanical model. Additionally, we compared the model-based predictions with experimental data from chronic low back pain patients and healthy controls using surface-electromyography. Linear stability methods were applied to the musculoskeletal model, which was extended with a time-delayed reflex model. Lateral external perturbations were simulated around equilibrium to investigate the effects of reflex delay and gain on the stability of the human lumbar spine. The model simulations predicted that increased reflex delays require a reduction of the reflex gain to avoid spinal instability. The experimental data support this dependence for the investigated abdominal muscles in chronic low back pain patients and healthy control subjects. Reflex time-delay and gain dependence showed that a delayed reflex latency could have relevant influence on spinal stability, if subjects do not adapt their reflex amplitudes. Based on the model and the experimental results, the relationship between muscle reflex response latency and the maximum of the reflex amplitude should be considered for evaluation of (patho) physiological data. We recommend that training procedures should focus on speeding up the delayed reflex response as well as on increasing the amplitude of these reflexes.     

The dynamics of successive induction in larval zebrafish

Charles Sherrington identified the properties of the synapse by purely behavioral means—the study of reflexes—more than 100 years ago. They were subsequently confirmed neurophysiologically. Studying reflex interaction, he also showed that activating one reflex often facilitates another, antagonistic one: successive induction, which has since been demonstrated in a wide range of species, from aphids to locusts to dogs and humans. We show a particularly orderly example in zebrafish (Danio rerio) larvae; the behavior (locomotion) of larvae is low in dark and intermediate in light, but low in light and substantially higher in dark when dark followed light. A quantitative model of a simple dynamic process is described that readily captures the behavior pattern and the effects of a number of manipulations of lighting conditions.     

The Moro reaction: More than a reflex,a ritualized behavior of nonverbal communication

ObjectiveTo propose a phylogenetic significance to the Moro reflex which remains unexplained since its publication in 1918 because both hands are free at the end of the gesture.MethodAmong the 75 videos of healthy term newborns we have filmed in a research project on antenatal education to parenthood, we describe a sequence that clearly showed the successive movements of the Moro reflex and we report the occurrence of this reflex in the videos that were recorded from Time 0 of birth defined as the moment that lies between the birth of the thorax and the pelvis of the infant.ResultsThe selected sequence showed the following succession of the newborn’s actions: quick extension-adduction of both arms, the orientation of the body, head and eyes towards a human person, and full extension-abduction of both arms with spreading of the fingers, crying and a distressed face. There were 13 Moro reflexes between 2 and 14 s from Time 0 of birth. We found a significant association between the occurrence of the Moro reflex and the placement of the newborn at birth in supine position on the mother’s abdomen (p = 0.002).DiscussionThe quick extension-adduction of both arms which started the sequence may be considered as a startle reflex controlled by the neural fear system and the arm extension-adduction which followed as a Moro reflex. The characteristics of all Moro reflexes were those of ritualization: amplitude, duration, stereotype of the gestures. This evolutionary process turns a physiological behavior, grasping in this case, to a non-verbal communicative behavior whose meaning is a request to be picked up in the arms. The gestures associated with the Moro reflex: crying and orientation of the body, head, and eyes towards a human person, are gestures of intention to communicate which support our hypothesis. The neural mechanism of the Moro reaction probably involves both the fear and the separation-distress systems.ConclusionThis paper proposes for the first time a phylogenetic significance to the Moro reflex: a ritualized behavior of nonverbal communication. Professionals should avoid stimulating the newborns’ fear system by unnecessarily triggering Moro reflexes. Antenatal education should teach parents to respond to the Moro reflexes of their newborn infant by picking her up in their arms with mother talk.     

Phase-dependent reflex modulation in tibialis anterior during passive viewing of walking

It is well established that reflexes are highly adaptive, as they depend both on our intention and on the active state of the muscles. Reflex gains change dynamically during actions such as walking and running, with the gain of cutaneous reflexes being increased at the end of the stance phase but decreased at the end of the swing phase in the tibialis anterior (TA) muscle. Reflex gains can even change during the mere observation of an action. The mechanisms and functions of such modulations are unclear. It has been suggested that the changed reflex gains prevent the actual performance of actions that we see. However, the modulation of reflexes in response to seeing an action has never been reproduced for the active execution of such actions. In the present study, medium-latency cutaneous reflexes from the TA muscle, of which the activity and reflexes during walking are well known, were measured in human subjects. The results show that the gain changes of the medium-latency responses of the TA are the same as during active walking. We conclude that reflexes do not represent an inhibitory mechanism that prevents motor output during action observation. Instead, our findings provide evidence that even the peripheral spinal motor system is actively involved in the motor resonance processes, without evoking any measurable motor responses.     

Reflex responses of human lip muscles to mechanical stimulation during speech

The role played by reflex pathways in the production of movement has been a significant issue for motor control theorists interested in a wide variety of motor behaviors. From studies of locomotion and chewing, it appears that gains in reflex pathways can be altered so that activity in these pathways does not produce destabilizing responses during movement. In speech production, recent experimental evidence has been interpreted to suggest that autogenetic lip reflexes (perioral reflexes) are suppressed during sustained phonation or speech production. The present study was conducted to assess the effects of phonation, direction of movement, and ongoing speech production on reflex responses of lip muscles. The present results suggest, in contrast to earlier work, that this reflex pathway is not suppressed or absent because the amplitude of the observed response depends upon the activation levels of the various muscles of the lower lip and, therefore, indirectly on the nature of the gesture the subject is instructed to produce.     

Interaction between penile reflexes and copulation in male rats

Intact, unanesthetized male rats were place in a supine position, with the penile sheath continuously retracted. Three forms of penile reflex were displayed: erections, cups, and flips. The reciprocal relation between copulation and the penile reflexes occurring in supine tests was explored in four experiments. In Experiment 1, sexual exhaustion depressed all penile reflexes, but the reflexes returned to baseline levels within 8 hr, long before copulatory potential. In Experiment 2, reflexes were depressed to exhaustion levels after fewer ejaculations than were required for sexual exhaustion, an indication that reflexes are more readily evoked during copulation than in supine tests. Experiment 3 determined that a rat's penile-reflex potential may be enhanced by placing the rat in a copulation-test cage, by allowing the male a few antecedent intromissions, or by allowing an antecedent ejaculation. The display of penile reflexes within 1 min after ejaculation suggests that the period of reduced sexual arousability following ejaculation is not due to reduced excitability in the spinal mechanisms controlling penile reflexes. In Experiment 4, 1 hr of penile-reflex elicitation had no effect on subsequent copulatory behavior. Thus, sexual stimulation may increase or decrease penile-reflex potential, but a reciprocal influence was not detectable.     

Reflex Responses of Human Lip Muscles to Mechanical Stimulation During Speech

The role played by reflex pathways in the production of movement has been a significant issue for motor control theorists interested in a wide variety of motor behaviors. From studies of locomotion and chewing, it appears that gains in reflex pathways can be altered so that activity in these pathways does not produce destabilizing responses during movement. In speech production, recent experimental evidence has been interpreted to suggest that autogenetic lip reflexes (perioral reflexes) are suppressed during sustained phonation or speech production. The present study was conducted to assess the effects of phonation, direction of movement, and ongoing speech production on reflex responses of lip muscles. The present results suggest, in contrast to earlier work, that this reflex pathway is not suppressed during phonation or speech. However, the response may appear to be suppressed or absent because the amplitude of the observed response depends upon the activation levels of the various muscles of the lower lip and, therefore, indirectly on the nature of the gesture the subject is instructed to produce.     

Training-specific adaptations of H- and stretch reflexes in human soleus muscle

The authors investigated the effect of physical exercise on reflex excitability in a controlled intervention study. Healthy participants (N = 21) performed 4 weeks of either power training (ballistic strength training) or balance training (sensorimotor training [SMT]). Both training regimens enhanced balance control and rate of force development, whereas reductions in peak-to-peak amplitudes of stretch reflexes and in the ratio of the maximum Hoffman reflex to the maximum efferent motor response (Hmax:Mmax) measured at rest were limited to SMT. The differences in reflex excitability between the training regimens indicated different underlying neural mechanisms of adaptation. The reduced reflex excitability following SMT was most likely induced by supraspinal influence. The authors discuss an overall increase in presynaptic inhibition of Ia afferent fibers as a possible mechanism.     

Use of the conditional reflex to assess the temporal characteristics of curarization effects on heart rate responding

A Pavlovian methodological counterpart to the use of druginduced changes in operant rates of responding was used to assess the temporal characteristics of d-tubocurarine chloride effects on the heart rate conditional reflex in rats. After a stable conditional reflex had been established, the base heart rate, as well as the unconditional and conditional reflex, was monitored during administration of the drug. A sizable behavioral effect was reflected in all three measures, including a temporary abolition of the conditional and unconditional reflexes. An interpretation of these results was discussed, and further development and application of this specific methodology was explored.     

Heart rate deceleration is not an orienting reflex; Heart rate acceleration is not a defensive reflex

Graham and Clifton (1966) proposed an integration of Sokolov’s theory of orienting and defensive reflexes with the stimulus intake/rejection dichotomy of the Laceys. This integration consisted of hypothesizing that heart rate deceleration is a measure of the orienting reflex, and that cardiac acceleration is a measure of the defensive reflex. This article demonstrates that Graham and Clifton failed to establish a valid integration of these two theories. This failure is a consequence of 1) their misconstruing Sokolov’s theory, and 2) an inaccurate and selective review of the research literature then available. Consideration of more recent research would seem to rule out the possibility that their thesis was correct in spite of these flaws in its derivation. Cardiac responding in the OR context thus remains open to further investigation and interpretation.     

The Interrater Reliability of Subjective Assessments of the Babinski Reflex

The Babinski reflex is a clinical diagnostic tool; however, the interrater reliability of this tool is currently greatly contested. A comparison between rater groups with objective measurements of the Babinski reflex was therefore conducted. Fifteen recorded Babinski reflexes were assessed by 12 neurologists and 12 medical students as being either pathological or nonpathological. Kinematic and electromyographic variables were collected and used to assess which aspects of the Babinski reflex predict classification. Substantial interrater agreement within the neurologist and student groups (κ = .72 and .67, respectively) was shown; however, there were some differing aspects between what neurologists and students used to assess the reflex as determined by objective kinematic measurements.