Programming or inhibiting action: evidence for differential autonomic nervous system response patterns

Expertise and Peripheral Autonomic Activity during the Preparation Phase in Shooting Events

This study compared effectiveness of the concentration period in two groups of shooters to evaluate the influence of their expertise while concentrating on the target. Marksmen (pistol shooters, 10 men and 5 women) and pentathletes (6 men and 7 women) took part in a shooting competition in keeping with the rules of each event. Participants were then asked to imagine themselves shooting, at the laboratory. Five variables representing the activity of the autonomic nervous system were continuously recorded (skin resistance and potential, skin blood flow, skin temperature, instantaneous heart rate). Autonomic responses recorded during concentration, actual shooting, and mental imagery were compared by calculating the ratios concentration/shooting and imagery/shooting. The resultant mean ratio was used to characterize each participant. The same autonomic nervous system pattern was observed during concentrating on the target, mental imagery, and actual shooting. However, marksmen showed ratios closer to 1.0 than pentathletes, absolute mean differences being .06 and .3, respectively. Shorter duration and weakest amplitude responses were recorded during the concentration phase in the Pentathlete group, suggesting that they have more difficulty in using mental imagery during competition than marksmen. When subjects performed well, a specific response pattern was observed in the Marksman group, but not in the Pentathlete group, except in skin potential. In both Marksman and Pentathlete groups, a majority of negative skin potential responses were found in the concentration and shooting phases for the best shots.

Complementary neural correlates of motivation in dopaminergic and noradrenergic neurons of monkeys

Rewards have many influences on learning, decision-making, and performance. All seem to rely on complementary actions of two closely related catecholaminergic neuromodulators, dopamine (DA), and noradrenaline (NA). We compared single unit activity of dopaminergic neurons of the substantia nigra pars compacta (SNc) and noradrenergic neurons of the locus coeruleus (LC) in monkeys performing a reward schedule task. Their motivation, indexed using operant performance, increased as they progressed through schedules ending in reward delivery. The responses of dopaminergic and noradrenergic neurons around the time of major task events, visual cues predicting trial outcome and operant action to complete a trial were similar in that they occurred at the same time. They were also similar in that they both responded most strongly to the first cues in schedules, which are the most informative cues. The neuronal responses around the time of the monkeys' actions were different, in that the response intensity profiles changed in opposite directions. Dopaminergic responses were stronger around predictably rewarded correct actions whereas noradrenergic responses were greater around predictably unrewarded correct actions. The complementary response profiles related to the monkeys operant actions suggest that DA neurons might relate to the value of the current action whereas the noradrenergic neurons relate to the psychological cost of that action.

The effectiveness of exercise intervention on inhibitory control in children with developmental coordination disorder: using a visuospatial attention paradigm as a model

Children with developmental coordination disorder (DCD) have been demonstrated to show a deficit of inhibitory control in volitional shifts of attention. The aim of this study was to use ecological intervention to investigate the efficacy of table-tennis training on treating both problems with attentional networks and motor disorder in children with DCD. Forty-three children aged 9-10 years old were screened using the Movement Assessment Battery for Children and divided into DCD (n=27) and typically developing (TD, n=16) groups. Children with DCD were then quasi-randomly assigned to either a DCD-training group who underwent a ten-week table-tennis training program with a frequency of 3 times a week or a DCD non-training group. Before and after training, the capacity of inhibitory control was examined with the endogenous Posner paradigm task for DCD and TD groups. Table-tennis training resulted in significant improvement of cognitive and motor functions for the children with DCD. The study demonstrated that exercise intervention employed within the school setting can benefit the inhibitory control and motor performance in children with DCD. However, future research efforts should continue to clarify whether the performance gains could be maintained over time.

Brain activity during visual versus kinesthetic imagery: an fMRI study

Although there is ample evidence that motor imagery activates similar cerebral regions to those solicited during actual movements, it is still unknown whether visual (VI) and kinesthetic imagery (KI) recruit comparable or distinct neural networks. The present study was thus designed to identify, through functional magnetic resonance imaging at 3.0 Tesla in 13 skilled imagers, the cerebral structures implicated in VI and KI. Participants were scanned in a perceptual control condition and while physically executing or focusing during motor imagery on either the visual or kinesthetic components of an explicitly known sequence of finger movements. Subjects' imagery abilities were assessed using well-established psychological, chronometric, and new physiological measures from the autonomic nervous system. Compared with the perceptual condition, physical executing, VI, and KI resulted in overlapping (albeit non-identical) brain activations, including motor-related regions and the inferior and superior parietal lobules. By contrast, a divergent pattern of increased activity was observed when VI and KI were compared directly: VI activated predominantly the occipital regions and the superior parietal lobules, whereas KI yielded more activity in motor-associated structures and the inferior parietal lobule. These results suggest that VI and KI are mediated through separate neural systems, which contribute differently during processes of motor learning and neurological rehabilitation.

Relation of locus coeruleus neurons in monkeys to Pavlovian and operant behaviors

Noradrenaline is released throughout the forebrain from locus coeruleus (LC) projections in close temporal proximity to emotional and goal-directed events. To examine interactive influences of these processes on LC neuronal activity, we used a task where Pavlovian and operant processes vary and can be easily identified. We recorded 69 single LC neurons from two monkeys performing a task where cues indicate the progression through schedules of one, two, or three operant trials. Pavlovian responses and phasic LC activations occur following the appearance of conditioned visual cues (54/69 neurons), especially those at the beginning of new schedules, whether the current trial will be rewarded (single trial schedule) or not (2 or 3 trial schedules), and after visual imperative signals eliciting the operant response (64/69 neurons), whether the current trial will be rewarded or not. The modulation of LC responses seems to be relatively independent of attention or motivation, because the responses do not covary with operant performance in the task. The magnitude of LC responses across the schedules varied in close relation to the intensity of Pavlovian behavior but these responses were also modulated by operant processes. Our conclusion is that LC activation occurs when task-relevant stimuli evoke a conditioned instinctive (Pavlovian) response, with the strength of the activation also being modulated by goal-directed processes. Thus locus coeruleus neurons broadcast information about stimulus-elicited primitive and goal-directed behaviors to forebrain structures important for executive functions and emotions.

Muscular responses during motor imagery as a function of muscle contraction types

This study was designed to gain more insight into the mechanisms underlying motor imagery (MI). While there is ample evidence that motor performance and MI share common central neural mechanisms, the question whether MI is accompanied by subliminal electromyographic (EMG) activity remained unsolved. Thirty right-handed volunteers were asked to lift or to imagine lifting a weighted dumbbell using different types of muscle contraction, i.e. heavy concentric, light concentric, isometric and eccentric contractions. EMG activity from 9 muscles of the dominant arm (agonist, antagonist, synergist and fixator muscles) was monitored. Autonomic nervous system responses were also recorded on the non-dominant hand, thus attesting mental activity at the peripheral level. A significant increased pattern of EMG activity was recorded in all muscles during MI, when compared to the rest condition, while the goniometric data did not reveal any movement. Although being subliminal, the magnitude of this activation was found to be correlated to the mental effort required to lift a weight mentally, as more EMG activity was recorded during imaginary lifting of heavy than light concentric contractions. When considering the different types of contraction, our results provided evidence of selective changes in EMG activity. Especially, the imagined eccentric condition elicited a significant weaker muscular activity than all other conditions. In addition, the changes in the EMG pattern mirrored those usually observed during physical movement. These findings support the hypotheses of a selective effect of MI at the level of muscular activity and of incomplete inhibition of the motor command during MI.

Observation of action and autonomic nervous system responses

Observing somebody performing an action has been shown to elicit neuronal activity in the premotor cortex. This paper investigated physiological effect of observing an effortful action at the peripheral level. As Autonomic Nervous System responses reflect central nervous system processes such as movement planning and programming, it was expected that observing an action would elicit a pattern of ANS responses matching those recorded during actual movement. 12 male subjects, ages 23 to 28 years (M = 25.5, SD = 1.9), were selected as they were experienced in weight lifting. They were asked to observe a squat movement followed by returning to the upright position under 3 different conditions: (i) observation of actual movement performed by somebody else, (ii) observation of a video of the subject himself (first-person video), and (iii) observation of a video of somebody else performing the same movement (third-person video). Moreover, each movement was observed when performed at 50% and 90% of each participant's personal best mark (% of the highest weight which could be lifted). Three ANS parameters were continuously recorded: skin resistance, temperature and heart rate. ANS responses varied as a function of movement intensity: autonomic responses recorded during movement observation at 90% were significantly higher and longer than those recorded during movement observation at 50%. Thus, autonomic responses were linked to the amount of observed effort. Conversely, no difference was found among the three conditions of observation. ANS responses from observation of actual movement were shown to resemble those recorded under the two conditions of video observation.

Contribution from neurophysiological and psychological methods to the study of motor imagery

This paper reviews studies on neurophysiological and behavioral methods used to evaluate motor imagery accuracy. These methods can be used when performed in the field and are based on recordings of peripheral indices such as autonomic nervous system or electromyographic activities, mental chronometry and psychological tests. Providing physiological signs that correlate to these types of mental processes may be considered an objective approach for motor imagery analysis. However, although autonomic nervous system activity recording has been shown to match motor imagery in real time, to evaluate its accuracy qualitatively and the individual ability to form mental images, the relationship between physiological responses and mental processes remains an inference. Moreover, electromyographic recordings may be associated with postural control data, but due to inconsistent results, they remain insufficient to solely evaluate motor imagery accuracy. Other techniques traditionally used in psychology and cognitive psychology are questionnaires, "debriefing" with subjects and mental chronometry. Although such methods lead to interesting results, there remains an important part of subjectivity as subjects perform an auto-evaluation of motor imagery accuracy. Similarly, mental chronometry gives information on the ability to preserve temporal organization of movement but does not allow the evaluation of the vividness of mental images. Thus, several methods should be combined to analyze motor imagery accuracy in greater detail. Neurophysiological recordings cannot therefore be considered an alternative but rather a complementary technique to behavioral and psychological methods. The advantages and inconvenient of each technique and the hypotheses that could be tested are discussed.

Action, arousal, and subjective time

Saccadic chronostasis refers to the subjective temporal lengthening of the first visual stimulus perceived after an eye movement. It has been quantified using a duration discrimination task. Most models of human duration discrimination hypothesise an internal clock. These models could explain chronostasis as a transient increase in internal clock speed due to arousal following a saccade, leading to temporal overestimation. Two experiments are described which addressed this hypothesis by parametrically varying the duration of the stimuli that are being judged. Changes in internal clock speed predict chronostasis effects proportional to stimulus duration. No evidence for proportionality was found. Two further experiments assessed the appropriateness of the control conditions employed. Results indicated that the chronostasis effect is constant across a wide range of stimulus durations and does not reflect the pattern of visual stimulation experienced during a saccade, suggesting that arousal is not critical. Instead, alternative processes, such as one affecting the onset of timing (i.e., the time of internal clock switch closure) are implicated. Further research is required to select between these alternatives.

The Physiological Activation Effect on Performance in Shooting

Abstract The present study was devised to analyze the relationship between sporting performance and physiological activation. Fourteen subjects participated in a modern pentathlon shooting competition. Six autonomic nervous system (ANS) parameters were simultaneously recorded in real time: Skin Potential, Skin resistance, Instantaneous Heart Rate and Respiratory Frequency, Skin Temperature, and Skin Blood Flow. The duration of concentration was considered the time lapse between the “start” order and the shot. Subjects tried to keep their arm and pistol stable during this phase. Results showed a complex relationship between activation, relaxation, and performance. ANS activity indicated an increase in physiological activation and at the same time, relaxation: activation was observed through electrodermal activity, while thermovascular indices indicated relaxation. Tonic level variations were, thus, a reliable indicator of the contrasting requirements of this sporting activity. Finally, the results challenge theories that have suggested that autonomic activity is undifferentiated.

Autonomic nervous system activity associated with postural disturbances in patients with perilymphatic fistula: sympathetic or vagal origin?

The study focused on patients suffering from perilymphatic fistula (PLF), whether they had undergone surgery or not. Vestibular disturbances can be harmless but are associated with varying symptoms, demonstrating disorders within the autonomic nervous system (ANS). The aim was to test whether the orthosympathetic is involved as the vagal part is often suspected of eliciting a feeling of sickness. Non-invasive and uninterrupted recording of ANS activity represents an objectivation technique to evidence such disturbances. Electrodermal activity, thermovascular variables, instantaneous cardiac rate and blood pressure were recorded. Discomfort was triggered experimentally by applying various stimulations successively to the intact ear then to the PLF (or operated) side. Twelve subjects took part in the experiment. Two types of ANS activity were distinguished: (1) phasic responses during stimulation and (2) tonic evolution thereafter. Results show strong activation in orthosympathetic variables when the PLF side was stimulated. No further significant difference between the two sides was to be observed following surgery. After stimulation, a sudden increase in skin resistance was observed, associated with slight bradycardia. No vagal signs having been evidenced, actual nausea may result from brief inhibition of sympathetic activation resulting, in turn from primary over-activation of this system.