E. Vernet-Maury

Relationship between mental imagery and sporting performance

Simultaneous measurement of six autonomic nervous system (ANS) variable responses during mental rehearsal of an action, makes it possible to draw a parallel between mental imagery of a task and its actual execution. The experiment was carried out in the field during precision shooting competitions and in the laboratory for imagery activity, on 22 subjects. Results show that there is similarity of ANS response in the three situations: the period of concentration prior to shooting, actual shooting and mental representation of shooting. The ratio formed by ANS response during concentration and imagery of actual firing tends towards the value one, therefore towards some identity. All subjects may be classified around this value; it is worth noting that subject distribution around this value corresponds to performance value. It seems that the better the subject, the closer his concentration/shooting or imagery/actual shooting ratio is to the theoretical value one. These results show the utmost importance of the quality of mental representation for performance improvement. It can be supposed that subject classification above the theoretical value one corresponds to overflowing emotional reactivity in one of the two phases and that this interferes with accuracy; a placing below the theoretical value one shows a lack of similarity between mental representation and the action.

Bioelectric and microcirculation cutaneous sensors for the study of vigilance and emotional response during tasks and tests

Bioelectronic phenomena related to the activity of the Autonomic Nervous System (ANS) activity mainly take place in the deep part of the brain where they are difficult to record. The hand skin, being richly innervated by sympathetic efferent fibres, offers an interface from which relevant ANS-related signals can be recorded. Two non-invasive bioelectronic measurements (skin resistance and potential) reflecting the activity of the ANS were performed at the skin surface. These measurements were complemented by thermovascular (skin microcirculation and skin temperature) and cardiorespiratory (instantaneous heart rate and instantaneous respiratory frequency) measurements. The bioelectric measurements were performed using noninvasive Ag/AgCl electrodes. Non-metallic NASICON (Na Super Ionic Conductor) electrodes were tested and compared with traditional electrodes for the optimization of bioelectric measurements. Signal analysis and data processing was accomplished by means of original indices on a specially designed PC-based software. The methodology was used to evaluate vigilance level, mental workload, and emotional response during tasks (sporting activity, mental calculation, olfactive stimuli) and in critical situations (car crash avoidance).

Increased activation as a limiting factor of performance in sharp shooters

The measurement of autonomic nervous system (ANS) activity was performed on 10 male and five female sharp shooters (rifle) during competitions. Electrodermal, thermovascular, cardiorespiratory variables and two indices of performance were recorded simultaneously. When the subjects fired shots that hit the target, they had a higher number of negative skin potential responses than when they missed. The responses had lower amplitude but lasted longer than when the shots missed the target. Good performance seemed to depend on high levels of motivation (increase in negative potential response), better mastery of the emotional reactivity (low amplitude response), and greater concentration time (increased duration of response).

Analysis Of Skin Potential Response Using A Novel Feature Code For The Study Of The Emotional Response

The skin electrodermal activity and the skin potential response (S.P.R.) are related to mental activity, emotional response and the level of arousal. A feature code for the study of the S.P.R. was designed from three positive and three negative elementary shapes. By this method, the S.P.R. can be broken up into its elementary shapes constituents. This method was used in correlation with skin blood and skin conductance for the study of the emotional response in marksmen (archery and pistol) during competition. Using this software, the operator has only to indicate the start and the end of the signal to be studied.

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.

Autonomic nervous system response pattern specificity to basic emotions

The aim of this study was to test the assumption that the autonomic nervous system responses to emotional stimuli are specific. A series of six slides was randomly presented to the subjects while six autonomic nervous system (ANS) parameters were recorded: skin conductance, skin potential, skin resistance, skin blood flow, skin temperature and instantaneous respiratory frequency. Each slide induced a basic emotion: happiness, surprise, anger, fear, sadness and disgust. Results have been first considered with reference to electrodermal responses (EDR) and secondly through thermo-vascular and respiratory variations. Classical as well as original indices were used to quantify autonomic responses. The six basic emotions were distinguished by Friedman variance analysis. Thus, ANS values corresponding to each emotion were compared two-by-two. EDR distinguished 13 emotion-pairs out of 15. 10 emotion-pairs were separated by skin resistance as well as skin conductance ohmic perturbation duration indices whereas conductance amplitude was only capable of distinguishing 7 emotion-pairs. Skin potential responses distinguished surprise and fear from sadness, and fear from disgust, according to their elementary pattern analysis in form and sign. Two-by-two comparisons of skin temperature, skin blood flow (estimated by the new non-oscillary duration index) and instantaneous respiratory frequency, enabled the distinction of 14 emotion-pairs out of 15. 9 emotion-pairs were distinguished by the non-oscillatory duration index values. Skin temperature was demonstrated to be different i.e. positive versus negative in response to anger and fear. The instantaneous respiratory frequency perturbation duration index was the only one capable of separating sadness from disgust. From the six ANS parameters study, different autonomic patterns were identified, each characterizing one of the six basic emotion used as inducing signals. No index alone, nor group of parameters (EDR and thermovascular for instance) were capable of distinguishing each emotion from another. However, electrodermal, thermo-vascular and respiratory responses taken as a whole, redundantly separated each emotion thus demonstrating the specificity of autonomic patterns.

Continuous Skin Blood Flow Measurement By A Non Invasive Thermal Transducer (Hematron)

A non invasive transducer in shape of a disc (25 mm diameter 4 mm thickness) was designed for the measurement of Skin Blood Flow (S.B.F.) up to 1 Hz. The results obtained from the measurement of the skin thermal conductivity are expressed in absolute values ; so the measurement may be compared intra or inter subject and it is possible to compare experiments after long periods of time. This transducer allows a large field of applications in physiology, pharmacology m onitoring, f unctional exploration, psychophysiology and neurophysiology. It can be also use for the study of burnt skin, graft skin and for cosmetology.