Academic literature on the topic 'Motor control, rhythmic movements, sensory stimuli'

Several electrophysiological studies suggest that Parkinson's disease (PD) patients have a reduced tendency to entrain to regular environmental patterns. Here we investigate whether this reduced entrainment concerns a generalized deficit or is confined to movement-related activity, leaving sensory entrainment intact. Magnetoencephalography was recorded during a rhythmic auditory target detection task in 14 PD patients and 14 control subjects. Participants were instructed to press a button when hearing a target tone amid an isochronous sequence of standard tones. The variable pitch of standard tones indicated the probability of the next tone to be a target. In addition, targets were occasionally omitted to evaluate entrainment uncontaminated by stimulus effects. Response times were not significantly different between groups and both groups benefited equally from the predictive value of standard tones. Analyses of oscillatory beta power over auditory cortices showed equal entrainment to the tones in both groups. By contrast, oscillatory beta power and event-related fields demonstrated a reduced engagement of motor cortical areas in PD patients, expressed in the modulation depth of beta power, in the response to omitted stimuli, and in an absent motor area P300 effect. Together, these results show equally strong entrainment of neural activity over sensory areas in controls and patients, but, in patients, a deficient translation of the adjustment to the task rhythm to motor circuits. We suggest that the reduced activation reflects not merely altered resonance to rhythmic external events, but a compromised recruitment of an endogenous response reflecting internal rhythm generation. NEW & NOTEWORTHY Previous studies suggest that motor cortical activity in PD patients has a reduced tendency to entrain to regular environmental patterns. This study demonstrates that the deficient entrainment in PD concerns the motor system only, by showing equally strong entrainment of neural activity over sensory areas in controls and patients but, in patients, a deficient translation of this adjustment to the task rhythm to motor circuits.

ABSTRACT During the 9 months between conception and birth, the fetal brain is transformed from instructions in genes to a complex, highly differentiated organ. The human central nervous system (CNS) changes from a microscopic band of embryonic neuroblasts to a 350 gm mass with more than 109 interconnected highly differentiated neurons in the cortex alone. How this extraordinary growth results in sensomotor, cognitive, affective and behavioral development is still unexplored. The development of voluntary, cognitive and purposive activity from fetal to neonatal period is to analyze the developmental transformations of the brain expressed by development of movement patterns from prenatal through postnatal period. As the development of the brain is unique and continuing process throughout the gestation and after birth, it is expected that there is also continuity of fetal to neonatal movements which are the best functional indicator of developmental processes of the brain. Concerning the complexity, voluntary control and stereotype, there are at least four groups of movements: Reflexes, fixed action patterns, rhythmic motor patterns, and directed movements. Substantial indications suggest that spontaneous activity is a more sensitive indicator of brain dysfunction than reactivity to sensory stimuli in reflex testing. It was proved that assessment of general movements in high-risk newborns has significantly higher predictive value for later neurological development than neurological examination. Nutritional stress at critical times during fetal development can have persistent and potentially irreversible effects on organ function. Impaired intrauterine growth and development may antecede insufficient postnatal growth. Thus, it may be a marker of impaired central nervous system integrity because of adverse intrauterine conditions. Unfavorable intrauterine environment can affect adversely fetal growth. There is an association between postnatal growth and neurodevelopmental outcome. Concerning the continuity from fetus to neonate in terms of neurobehavior, it could be concluded that fetus and neonate are the same persons in different environment. While in the womb, fetus is protected from the gravity which is not so important for its neurodevelopment, postnatally the neonate is exposed to the gravity during the labor and from the first moments of autonomous life. Development of motor control is highly dependent on antigravity forces enabling erect posture of infant or young child. These environmental differences should be kept on mind during prenatal as well as postnatal assessment. How to cite this article Stanojevic M. Neonatal Aspects: Is There Continuity? Donald School J Ultrasound Obstet Gynecol 2012;6(2):189-196.

Our daily lives are filled with rhythmic movements, such as walking, sports, and dancing, but the mechanisms by which the brain controls rhythmic movements are poorly understood. In this review, we examine the literature on neuropsychological studies of patients with focal brain lesions, and functional brain imaging studies primarily using finger-tapping tasks. These studies suggest a close connection between sensory and motor processing of rhythm, with no apparent distinction between the two functions. Thus, we conducted two functional brain imaging studies to survey the rhythm representations relatively independent of sensory and motor functions. First, we determined brain activations related to rhythm processing in a sensory modality-independent manner. Second, we examined body part-independent brain activation related to rhythm reproduction. Based on previous literature, we discuss how brain areas contribute rhythmic motor control. Furthermore, we also discuss the mechanisms by which the brain controls rhythmic movements.

This study tested the role of the superior colliculus in generating movements of the mystacial vibrissae—whisking. First, we compared the kinematics of whisking generated by the superior colliculus with those generated by the motor cortex. We found that in anesthetized rats, microstimulation of the colliculus evoked a sustained vibrissa protraction, whereas stimulation of motor cortex produced rhythmic protractions. Movements generated by the superior colliculus are independent of motor cortex and can be evoked at lower thresholds and shorter latencies than those generated by the motor cortex. Next we tested the hypothesis that the colliculus is acting as a simple reflex loop with the neurons that drive vibrissa movement receiving sensory input evoked by vibrissa contacts. We found that most tecto-facial neurons do not receive sensory input. Not only did these neurons not spike in response to sensory stimulation, but field potential analysis revealed that subthreshold sensory inputs do not overlap spatially with tecto-facial neurons. Together these findings suggest that the superior colliculus plays a pivotal role in vibrissa movement—regulating vibrissa set point and whisk amplitude—but does not function as a simple reflex loop. With the motor cortex controlling the whisking frequency, the superior colliculus control of set point and amplitude would account for the main parameters of voluntary whisking.

SUMMARYThis paper addresses the problem of self-detection by a robot. The paper describes a methodology for autonomous learning of the characteristic delay between motor commands (efferent signals) and observed movements of visual stimuli (afferent signals). The robot estimates its own efferent-afferent delay from self-observation data gathered while performing motor babbling, i.e., random rhythmic movements similar to the primary circular reactions described by Piaget. After the efferent-afferent delay is estimated, the robot imprints on that delay and can later use it to successfully classify visual stimuli as either “self” or “other.” Results from robot experiments performed in environments with increasing degrees of difficulty are reported.

Volitional rhythmic motor behaviors such as limb cycling and locomotion exhibit spatial and timing regularity. Such rhythmic movements are executed in the presence of exogenous visual and nonvisual cues, and previous studies have shown the pivotal role that vision plays in guiding spatial and temporal regulation. However, the influence of nonvisual information conveyed through auditory or touch sensory pathways, and its effect on control, remains poorly understood. To characterize the function of nonvisual feedback in rhythmic arm control, we designed a paddle juggling task in which volunteers bounced a ball off a rigid elastic surface to a target height in virtual reality by moving a physical handle with the right hand. Feedback was delivered at two key phases of movement: visual feedback at ball peaks only and simultaneous audio and haptic feedback at ball-paddle collisions. In contrast to previous work, we limited visual feedback to the minimum required for jugglers to assess spatial accuracy, and we independently perturbed the spatial dimensions and the timing of feedback. By separately perturbing this information, we evoked dissociable effects on spatial accuracy and timing, confirming that juggling, and potentially other rhythmic tasks, involves two complementary processes with distinct dynamics: spatial error correction and feedback timing synchronization. Moreover, we show evidence that audio and haptic feedback provide sufficient information for the brain to control the timing synchronization process by acting as a metronome-like cue that triggers hand movement. NEW & NOTEWORTHY Vision contains rich information for control of rhythmic arm movements; less is known, however, about the role of nonvisual feedback (touch and sound). Using a virtual ball bouncing task allowing independent real-time manipulation of spatial location and timing of cues, we show their dissociable roles in regulating motor behavior. We confirm that visual feedback is used to correct spatial error and provide new evidence that nonvisual event cues act to reset the timing of arm movements.

Experiments were performed on human elbow flexor and extensor muscles and jaw-opening and -closing muscles to observe the effect on rhythmic movements of sudden loading. The load was provided by an electromagnetic device, which simulated the appearance of a smoothly increasing spring-like load. The responses to this loading were compared in jaw and elbow movements and between expected and unexpected disturbances. All muscles showed electromyographic responses to unexpected perturbations, with latencies of ∼65 ms in the arm muscles and 25 ms in the jaw. When loading was predictable, anticipatory responses started in arm muscles ∼200 ms before and in jaw muscles 100 ms before the onset of loading. The reflex responses relative to the anticipatory responses were smaller for the arm muscles than for the jaw muscles. The reflex responses in the arm muscles were the same with unexpected and expected perturbations, whereas anticipation increased the reflex responses in the jaw muscles. Biceps brachii and triceps brachii showed similar sensory-induced responses and similar anticipatory responses. Jaw muscles differed, however, in that the reflex response was stronger in masseter than in digastric. It was concluded that reflex responses in the arm muscles cannot overcome the loading of the arm adequately, which is compensated by a large centrally programmed response when loading is predictable. The jaw muscles, particularly the jaw-closing muscles, tend to respond mainly through reflex loops, even when loading of the jaw is anticipated. The differences between the responses of the arm and the jaw muscles may be related to physical differences. For example, the jaw was decelerated more strongly by the load than the heavier arm. The jaw was decelerated strongly but briefly, <30 ms during jaw closing, indicating that muscle force increased before the onset of reflex activity. Apparently, the force-velocity properties of the jaw muscles have a stabilizing effect on the jaw and have this effect before sensory induced responses occur. The symmetrical responses in biceps and triceps indicate similar motor control of both arm muscles. The differences in reflex activity between masseter and digastric muscle indicate fundamental differences in sensory feedback to the jaw-closing muscle and jaw-opening muscle.

1. An isolated preparation of the crayfish nervous system, comprising both the thoracic and the abdominal ganglia together with their nerve roots, has been used to study the influence of a single leg proprioceptor, the coxo-basal chordotonal organ (CBCO), on the fictive swimmeret beating consistently expressed in this preparation. Both mechanical stimulation of the CBCO and electrical stimulation of its nerve were used. 2. In preparations not displaying rhythmic activity, electrical or mechanical stimulations evoked excitatory postsynaptic potentials (EPSPs) in about 30 % of the studied motor neurones with a fairly short and regular delay, suggesting an oligosynaptic pathway. Such stimulation could evoke rhythmic activity in swimmeret motor nerves. The evoked swimmeret rhythm often continued for several seconds after the stimulus period. 3. When the swimmeret rhythm was well established, electrical and mechanical stimuli modified it in a number of ways. Limited mechanical or weak electrical stimuli produced a small increase in swimmeret beat frequency, while more extreme movements of the CBCO or strong electrical stimuli had a disruptive effect on the rhythm. 4. The effect of low-intensity stimulation on existing swimmeret beating was phase-dependent: it shortened the beat cycle when applied during the powerstroke phase and lengthened it when applied during the retumstroke phase. 5. Rhythmic mechanical stimulation of CBCO or electrical stimulation of the CBCO nerve entrained the swimmeret rhythm within a limited range in relative or absolute coordination. Note: To whom reprint requests should be sent.

We reported previously that both transcutaneous electrical spinal cord stimulation and direct pressure stimulation of the plantar surfaces of the feet can elicit rhythmic involuntary step-like movements in noninjured subjects with their legs in a gravity-neutral apparatus. The present experiments investigated the convergence of spinal and plantar pressure stimulation and voluntary effort in the activation of locomotor movements in uninjured subjects under full body weight support in a vertical position. For all conditions, leg movements were analyzed using electromyographic (EMG) recordings and optical motion capture of joint kinematics. Spinal cord stimulation elicited rhythmic hip and knee flexion movements accompanied by EMG bursting activity in the hamstrings of 6/6 subjects. Similarly, plantar stimulation induced bursting EMG activity in the ankle flexor and extensor muscles in 5/6 subjects. Moreover, the combination of spinal and plantar stimulation exhibited a synergistic effect in all six subjects, eliciting greater motor responses than either modality alone. While the motor responses to spinal vs. plantar stimulation seems to activate distinct but overlapping spinal neural networks, when engaged simultaneously, the stepping responses were functionally complementary. As observed during induced (involuntary) stepping, the most significant modulation of voluntary stepping occurred in response to the combination of spinal and plantar stimulation. In light of the known automaticity and plasticity of spinal networks in absence of supraspinal input, these findings support the hypothesis that spinal and plantar stimulation may be effective tools for enhancing the recovery of motor control in individuals with neurological injuries and disorders.

The present paper aimed at investigating the effects of rhythmic play on ID (Intellectually Disabled), children’s attention and memory functioning at the age range of 9-16 years. Research measures included Raven Colored progressive matrixes for children and Canners neuropsychological test and Vinland adaptive behavior scale questionnaire. Statistical population comprised all ID students in elementary schools in the city of Esfahan in the Iranian academic year 2011. The research sample consisted of 20 children with intellectual disability selected by using multistage random sampling. Then, homogeneous in sensory and motor skills, participants were divided into two groups of ten: control and experimental. After receiving the parental consent, the researchers applied rhythmic movements to experimental group twice a week 45 minutes for each session for three months as an intervention program. Eight rhythmic movements (play) were employed in this research. The results revealed that rhythmic movements would affect attention problems (focus of attention, sustained attention, shifting attention, divided attention and attention capacity), general attention, memory (short-term, long-term, working), as well as general learning problems in educable children with intellectual disability according to their performance scales.

The general aim of my research is the understanding of the mechanisms that underlie the control of the rhythmic voluntary movement, and how environmental stimuli, by effecting on the neuromuscular constraints, produce functional adaptations in the systems enrolled to control and stabilize sensorimotor coordination. In particular, my research is aimed to investigate whether and how timing mechanisms for the production of rhythmic movements are manipulable by environmental stimuli, and it explores whether a causal relationship subsists between the elicitation of a specific timing mode and the change of the precision performance.

The nervous system is an integrating system which acts rapidly by transmitting signals as electrical impulses over often considerable distances to coordinate bodily activities. The brain and spinal cord make up the central nervous system (CNS); incoming information travels in ascending (sensory) tracts that link the spinal cord to the brain and outgoing information passes down descending (motor) tracts linking the brain to the spinal cord. The CNS integrates responses to incoming information and sends the information to effector tissues (usually striated or smooth muscles or glands). Incoming and outgoing information is carried to and from the periphery to the CNS via 12 pairs of cranial nerves connected to the brain and 31 pairs of spinal nerves connected to the spinal cord; they constitute the peripheral nervous system (PNS). Sensory (afferent) information from the external environment is obtained through the organs of special sense in the eyes, ears, nose and tongue, and skin and mucosa lining bodily cavities: we are aware of these stimuli. Information from internal sources is equally important and vital for maintaining homeostasis, but we are usually Neurons are the basic cellular units of the nervous system. As the principal function of the nervous system is conduction of electrical signals over considerable distances, neurons are highly specialized for this f unction. Neurons have: • A specific shape with long cellular extensions; • Highly specialized membranes to control ionic movements to allow electrical activity to spread along the cellular extensions; • A very specialized internal transport system to distribute cellular metabolites along the processes. The general shape of neurons is shown in Figure 3.1. Note first of all, the relatively large cell body near the top of the picture; this contains the nucleus and the intracellular organelles necessary for synthetic functions so is similar to any other cell. What make neurons special are the long processes that emanate from the cell body. Dendrites are short multiple processes that branch extensively from and transmit impulses towards the cell body. Compare the dendrites in Figure 3.1 with the other process, the axon, which transmits impulses away from the cell body.

Can the imaginary brains described in Chapter 1 have only representations of perceived patterns, objects, and events? Can hierarchical structures of neurons also represent feelings, beliefs, emotions, and other higher mental states? Creating feelings requires giving emotional perceptions, memories, plans, beliefs, and intentions. How can this be achieved? How are perceived objects and events using their significance for the fate of the conscious system? Do they meet the various needs of the system? In this chapter we show that to achieve this goal, to feel qualia and to create phenomenal awareness, it is necessary to embody the mind. Mental states, such as thoughts and desires, contain intentional content that can be described by referring to something that we expect or believe. Another category are sensory feelings that do not contain intentional content but instead have different qualitative properties like perceptions, impressions, and sensations. The authors indicate four main domains of cooperation between the body and the brain, so that the mind generated in the system has phenomenal consciousness. These domains are 1) The homeostatic system. The body or housing may contain sensors informing the brain about the internal conditions of the body. The signals from these sensors can complement the information coming from the external senses. 2) The motor system. The housing and body, together with the motor system, allow an individual to manipulate objects in the environment and its own body in the environment. The effects of these manipulations can broaden the experience and allow for their evaluation. 3) Participatory analysis. The body or housing can be used to predict, analyze, and plan activities by making calculations through a physical process. 4) The global states of the organism. Internal power supply parameters, information-processing speed, dynamics of operation, and sensitivity thresholds for internal and external sensors can affect performance, the results of evaluation of sensations, and the shape of neural representations. This assumption makes it possible to explain how the imaginary mind can feel subjective impressions, the qualia that are the basis of phenomenal consciousness. The bodily reactions to the sensory stimuli reaching the brain can give value to individual feelings, and emotions. Feeling hardness or smoothness, assessing the attractiveness of smells, judging the importance of sounds, and evaluating the favor of the environment based on images all go beyond the direct response of the senses. The entire brain is involved in the creation of a conscious mind, along with sensory processing, control of movements, memories, predictions, and all other brain structures. This is an emergent phenomenon that is not reflected in any part of the brain's apparatus. In this chapter, the authors explain to what extent we can be aware of our feelings, how far we can understand the world around us and our place in it, how we can consciously direct our thoughts, and how we can focus attention on something.