Validation of a French version of the Freiburg Mindfulness Inventory - short version: relationships between mindfulness and stress in an adult population.

BACKGROUND: Whereas interest in incorporating mindfulness into interventions in medicine is growing, data on the relationships of mindfulness to stress and coping in management is still scarce. This report first presents a French validation of the Freiburg Mindfulness Inventory-short form (FMI) in a middle-aged working population. Secondly, it investigates the relationship between psychological adjustment and mindfulness. METHODS: Five hundred and six non-clinical middle-aged working individuals rated themselves on the self-report French version FMI and completed measures of psychological constructs potentially related to mindfulness levels. RESULTS: Results were comparable to results of the original short version. Internal consistency of the scale based on the one-factor solution was .74, and test-retest reliability was good. The one-dimensional solution as the alternative to the two-factor structure solution yielded suboptimal fit indices. Correlations also indicated that individuals scoring high on mindfulness are prone to stress tolerance, positive affects and higher self-efficacy. Furthermore, subjects with no reports of stressful events were higher on mindfulness. CONCLUSION: These data showed that mindfulness can be measured validly and reliably with the proposed French version of the FMI. The data also highlighted the relationship between mindfulness and stress in an adult population. Mindfulness appears to reduce negative appraisals of challenging or threatening events.

Effect of low gravitational stimulation on the perception of target elevation: role of spatial expertise.

To examine the interindividual differences in the judgment of the visually perceived eye level (VPEL-upright position) and of the visually perceived apparent zenith (VPAZ-supine position) when the subject is subjected to low gravitational-inertial force (GIF), we independently altered GIF in two different populations: control subjects and spatial experts. Subjects were instructed to set a luminous target to the eye level while they were in total darkness and motionless or undergoing low radial acceleration with respect to the threshold of the otolithic system (0.015-1.67 m/sec2 for the VPEL and 0.55-2.19 m/sec2 for the VPAZ, respectively). Results showed that (1) low GIFs, close to those met during daily life, induced an eye level lowering in the upright and supine positions for the control group, and (2) the spatial expertise modified the influence of low GIF. Whereas an oculogravic illusion was found for the control group, this phenomenon was absent (VPAZ) or weaker (VPEL) for the spatial experts. Thus, the relations that the subjects maintain with their spatial environment and the knowledge acquired through experience modify the processing of sensory information and the perceptive construction resulting from it. The interindividual differences in sensitivity to the oculogravic illusion are discussed in terms of sensory dominance and of a better efficiency in the use of the available sensory information.

Contribution of tactile and interoceptive cues to the perception of the direction of gravity.

Without relevant visual cues, the Subjective Visual Vertical (SVV) is biased in roll tilted subjects toward the body axis (Aubert or A-effect). This effect is generally ascribed to changes in the vestibular and somatosensory inputs following a body tilt. This study focused on the contribution of interoception and tactile cues in the SVV. The body-cast technology and gastric fullness were used to obtain a diffuse tactile stimulation and an overload stomach stimulation, respectively. Fifteen subjects placed in a tilt-chair were rolled sideways from 0 degrees to 90 degrees. They were asked to adjust a luminous line to the vertical under two body restriction conditions (strapped vs. body-cast) and two stomach load conditions (empty vs. full). Results showed (1) an improvement in the SVV judgment when somaesthetic cues were available in the full stomach condition (p < 0.001), (2) an increased A-effect for the higher body tilt values in the body-cast condition (beyond 45 degrees, p < 0.001), and (3) a smaller disrupting effect of the body-cast in the SVV judgment in the full stomach condition (p < 0.05). Since the vestibular system produced the same gravity response in all conditions, it can be stated that somaesthetic cues are involved in the SVV. Tactile mechanoreceptors may have contributed by detecting the changing pattern of pressures generated on the skin that results from changes in body orientation. The stomach load may act through the inertial forces exerted against the gravity load when the stomach is full by the mechanoreceptors in the fundus. Thus, the somaesthetic system can indicate the direction of gravity via patterns of pressure within and at the surface of the body.

Contribution of somesthetic information to the perception of body orientation in the pitch dimension.

This study investigated the contribution of otolithic and somesthetic inputs in the perception of body orientation when pitching at very slow velocities. In Experiment 1, the subjects' task was to indicate their subjective postural vertical, in two different conditions of body restriction, starting from different angles of body tilt. In the "strapped" condition, subjects were attached onto a platform by means of large straps. In the "body cast" condition, subjects were completely immobilized in a depressurized system, which attenuates gravity-based somesthetic cues. Results showed that the condition of body restriction and the initial tilt largely influenced the subjective postural vertical. In Experiment 2, subjects were displaced from a vertical position and had to detect the direction of body tilts. Results showed that the threshold for the perception of body tilt was higher when subjects were immobilized in the body cast and when they were tilted backward. Experiment 3 replicated the same protocol from a supine starting position. Compared to results of Experiment 2, the threshold for the perception of body tilt decreased significantly. Overall, these data suggested that gravity-based somesthetic cues are more informative than otolithic cues for the perception of a quasi-static body orientation.

Contribution of somesthetic cues to the perception of body orientation and subjective visual vertical.

Without relevant visual cues, the subjective visual vertical (SVV) is biased in roll-tilted subjects toward the body axis (Aubert or A-effect). This study focused on the role of the somatosensory system with respect to the SVV and on whether somesthetic cues act through the estimated body tilt. The body cast technology was used to obtain a diffuse tactile stimulation. An increased A-effect was expected because of a greater underestimation of the body position in the body cast. Sixteen subjects placed in a tilt chair were rolled sideways from 0 degrees to 105 degrees. They were asked to verbally indicate their subjective body position and then to adjust a luminous line to the vertical under strapped and body cast conditions. Results showed a greater A-effect (p < .001) but an overestimation of the body orientation (p < .01) in the body cast condition for the higher tilt values (beyond 60 degrees). Since the otolith organs produced the same gravity response in both conditions, errors were due to a change in somesthetic cues. Visual and postural errors were not directly related (no correlation). However, the angular distance between the apparent body position and the SW remained stable, suggesting that the change in somatosensory pattern inputs has a similar impact on the cognitive processes involved in assessing the perception of external space and the sense of self-position.

Effects of modafinil on heat thermoregulatory responses in humans at rest.

The effects of modafinil on heat thermoregulatory responses were studied in 10 male subjects submitted to a sweating test after taking 200 mg of modafinil or placebo. Sweating tests were performed in a hot climatic chamber (45 degrees C, relative humidity <15%, wind speed = 0.8 m x s(-1), duration 1.5 h). Body temperatures (rectal (Tre) and 10 skin temperatures (Tsk)), sweat rate, and metabolic heat production (M) were studied as well as heart rate (HR). Results showed that modafinil induced at the end of the sweating test higher body temperatures increases (0.50 +/- 0.04 versus 0.24 +/- 0.05 degrees C (P < 0.01) for deltaTre and 3.64 +/- 0.16 versus 3.32 +/- 0.16 degrees C (P < 0.05) for deltaTsk (mean skin temperature)) and a decrease in sweating rate throughout the heat exposure (P < 0.05) without change in M, leading to a higher body heat storage (P < 0.05). AHR was also increased, especially at the end of the sweating test (17.95 +/- 1.49 versus 12.52 +/- 1.24 beats/min (P < 0.01)). In conclusion, modafinil induced a slight hyperthermic effect during passive dry heat exposure related to a lower sweat rate, probably by its action on the central nervous system, and this could impair heat tolerance.

Over-stimulation of the vestibular system and body balance.

The purpose of this study was to examine whether an over-stimulation of the vestibular system, induced by thousands of time saccadic head stimulations, affects the vestibular sensitivity, and consequently if such a phenomenon could contribute to the deterioration of postural stability observed after a long distance running exercise. Eighteen athletic subjects performed a 20.5 km over ground race with an average speed of 15 km x h(-1), corresponding roughly to 7,500 strides shocks with associated saccadic accelerations transmitted to the head. A preliminary validation of the exercise protocol was realized to confirm the effect of the sustained exercise on body balance by recording standard postural parameters. A visually perceived eye level (VPEL) task was used to indirectly assess otolithic sensitivity motionless or undergoing low centrifugation conditions, before and after exercise. Results obtained from body balance analysis confirmed a decreased postural stability illustrated by increased postural oscillations after the 20.5 km run. Under low centrifugation conditions, results showed a lowering of the VPEL with the increase of the gravito-inertial acceleration in accordance with the literature. However, no significant change in the VPEL after a sustained running exercise was observed. In conclusion, the vestibular sensitivity at the otolithic level does not seem to be altered by an intensive running exercise and then failed to play a key role in the post-exercise deterioration of postural stability.

Perception of slow pitch and roll body tilts in bilateral labyrinthine-defective subjects.

The aim of the present study was to examine whether the perception of slow body tilts in total darkness was affected by a complete loss of vestibular function. Four blindfolded bilateral labyrinthine-defective subjects (LDs) and 12 normal subjects (Normals) were seated and immobilized with large straps against the back of a rotating L-shaped platform, and were passively displaced from the upright at 0.05 degrees x s(-1) in the pitch and roll dimensions. Subjects were asked to detect the slow change in their body orientation, by indicating as soon as possible the direction of tilt. After a brief period of practice observed for all LDs at the beginning of the session, results showed no significant difference between LDs and Normals in the mean detection threshold recorded for each direction of tilt. The mean perceptual threshold was 4.4 versus 5.1 degrees in the roll dimension, and 6.1 versus 6.1 degrees in the pitch dimension, for the LDs and Normals, respectively. These findings indicate that the accurate perception of body orientation in quasi-static conditions is mainly allowed by somatosensory information rather than by otolithic inputs.