To the self and beyond: Arousal and functional connectivity of the temporo-parietal junction contributes to spontaneous sensations perception.

The temporoparietal junction (TPJ), along with the anterior insula (AI) and the extrastriate body area (EBA), play a major part in embodiment and self-awareness. However, these connections also appear to be frequently engaged in arousal and attentional processing of external events. Considering that these networks may focus attention both toward and away from the self, we set to investigate how they contribute to the perception of spontaneous sensations (SPS), a common phenomenon related to self-awareness and mediated by both interoceptive and attentional processes. In Experiment 1, resting-state EEG was recorded, as well as arousal reported via a questionnaire, followed by a SPS task. Functional TPJ-AI and TPJ-EBA connectivity were computed using eLORETA. Spatial correlational analyses showed that less frequent SPS coincided with greater TPJ-AI and TPJ-EBA functional connectivity, especially in the theta and alpha frequency bands. High self-reported arousal predicted low intensity and low confidence in the location of SPS. Resting-state skin conductance level (SCL) was recorded in Experiment 2, followed by the SPS task. Less frequent SPS coincided with greater SCL. Findings are interpreted in terms of attention and self-related processes, and a discussion of the TPJ participation in self-awareness through SPS is presented.

Do Older People Accurately Estimate the Length of Their First Step during Gait Initiation?

Background/Study Context: Advancing age is associated with a decrease in step length. In line with previous studies showing that older adults often overestimate their motor abilities, we investigate whether older adults overestimate the length of their first step during gait initiation. The underlying effect could be a failure to update the internal model of motor action as a function of age-related motor decline. Methods: Without taking a step, community-dwelling older women (n = 22, age range: 68-87 years) and younger women (n = 19, age range: 19-33 years) estimated the length of their first step for both preferred step length and largest step length, which were performed without endangerment. Thereafter, the participants performed real gait initiation for both types of steps. The estimated step lengths were compared to the actual step lengths. Results: Older adults judged their first step as larger than it was (mean error: 30% for the preferred step and 9% for the largest step). A fine-grained analysis showed that this effect mainly concerned those for whom an increased risk of falling was suspected. These older adults were also among those who performed the shortest steps, and they presented with a slight decrease in cognitive functioning. Younger participants underestimated their preferred step length. Overall, the estimates were more accurate for the largest steps than for the preferred-length steps. Conclusion: Step length estimation revealed powerful evidence for overestimation in older adults. Those who overestimated step length presented with more signs of motor decline. While this result sustains the idea of an insufficient actualization of the motor-action model, the explanation also refers to more global appraisal processes. Further research should explore the relevance of this task as a clinical laboratory tool for assessing gait capacity and the risk of falling.

Time pressure and regulations on hospital-in-the-home (HITH) nurses: An on-the-road study.

This study investigated both causal factors and consequences of time pressure in hospital-in-the-home (HITH) nurses. These nurses may experience additional stress from the time pressure they encounter while driving to patients' homes, which may result in greater risk taking while driving. From observation in natural settings, data related to the nurses' driving behaviours and emotions were collected and analysed statistically; semi-directed interviews with the nurses were analysed qualitatively. The results suggest that objective time constraints alone do not necessarily elicit subjective time pressure. The challenges and uncertainty associated with healthcare and the driving period contribute to the emergence of this time pressure, which has a negative impact on both the nurses' driving and their emotions. Finally, the study focuses on anticipated and in situ regulations. These findings provide guidelines for organizational and technical solutions allowing the reduction of time pressure among HITH nurses.

How we perceive our own hands: Effects of attention, aging, and sex.

This study investigates whether both the perception of somesthetic sensations arising spontaneously on the hand and their modulation by attention are subject to change with advancing age and sex. Participants aged between 50 and 68 (N = 24), and younger (19-27; N = 24), with an equal sex ratio in each group, described the spontaneous sensations they felt on one of their hands. Two 10-s tests were carried out with participants either seeing their tested hand (gaze towards the visible hand) or not (contralateral gaze, hidden hand). Within the age range covered by our participants, aging had an effect on the spatial distribution of sensations, insofar as the older participants reported feeling more sensations in their palm whereas the younger participants had more sensitive fingers. Age also influenced the number, nature, intensity, and duration of sensations in interaction with gaze and/or sex. The most frequent pattern was a benefit of ipsilateral relative to contralateral gazing in young women. Attentional modulation was seldom observed in men and was absent among older participants.

My heart is in my hands: the interoceptive nature of the spontaneous sensations felt on the hands.

Somatic sensations may arise in the total absence of external stimuli, i.e., spontaneous sensations (SPSs). Because the background of body sensations has been mentioned as a possible contributor to interoceptive functions, such as the perception of the self and the conscious awareness of one's own body, a possible link between SPSs and interoception has been advocated. Yet, no study has provided direct evidence on such a relationship. The aim of the present study was to establish a link between SPSs and interoception. On the basis of the literature, the accuracy of heartbeat perception was taken as an index of general interoception across different bodily modalities. It was found that individuals with good heartbeat perception experienced more numerous and more intense SPSs. Furthermore, taken along with other individual characteristics, heartbeat perception accuracy predicted the perceived intensity of SPSs, their spatial extent, their variety, as well as confidence in their spatial characteristics. However, we also provide evidence that good vs. poor heartbeat perception is not just a matter of degree. We conclude that interoception definitely contributes to the perception of SPSs.

How do time pressured drivers estimate speed and time?

The purpose of this laboratory study was to investigate the influence of time pressure on the perception of speed and duration in driving situations. Participants provided estimations of speed and performed both productions and reproductions of time durations, based on traffic films. The experimental films were made from a driver's point of view within a moving car, and audio-recorded instructions invited participants to imagine that they were driving while under time pressure or while relaxed. The results obtained using this within-participant design support the hypothesis that time pressure promotes fast driving, and may induce an underestimation of speed and trip-related durations, the latter of which suggests that time pressure modulates time perception. Some of these effects were mediated by the emotional impact of time pressure. Links between time perception and speed were also observed. The discussion makes reference to internal clock models and focuses on the practical consequences of these results.

Interacting effects of vision and attention in perceiving spontaneous sensations arising on the hands.

Visual input and attention enhance tactile perception. But do they influence the perception of spontaneous sensations (SPS) arising in the absence of any external stimulus? We have investigated this by requiring subject to focus attention on each hand while orienting overtly toward it (convergent focusing) or away (divergent focusing) and to subsequently describe the properties of the SPS they felt. Subjects performed this task under free viewing conditions or while blindfolded. Enhanced perception of SPS was found under convergent focusing and also under free viewing conditions. However, the effects of focusing were different whether visual input was available or not. When visual input was available, SPS were enhanced in the fingers but suppressed in the palm, suggesting that enhancement and suppression operated to refine perception of SPS. When visual input was unavailable, only enhancement was observed, even in areas of the hand where suppressing effects were found under free viewing conditions. These interacting effects between vision and attention were observed exclusively in the left hand. A control experiment failed to evidence whether looking at different parts of the hand modulates SPS. We suggest that vision facilitates perception and, when interacting with attention, it enables better perception by promoting suppression of SPS arising in areas of lower sensitivity that may interfere with processing in more sensitive zones. The results are discussed with respect to mechanisms lateralized in the right cerebral hemisphere, and a role of SPS in the maintenance of a conscious image of the body is suggested.

The tickly homunculus and the origins of spontaneous sensations arising on the hands.

Everyone has felt those tingling, tickly sensations occurring spontaneously all over the body in the absence of stimuli. But does anyone know where they come from? Here, right-handed subjects were asked to focus on one hand while looking at it (convergent focusing) and while looking away (divergent focusing) and subsequently to map and describe the spatial and qualitative attributes of sensations arising spontaneously. The spatial distribution of spontaneous sensations followed a proximo-distal gradient, similar to the one previously described for the density of receptive units. The intensity and spatial extent of the reported sensations were modulated by the focusing condition, especially in respect of the left hand. Convergent focusing acted upon the conscious perception of sensations by enhancing or suppressing them. To our knowledge, this is the first ever study of spontaneous sensations, and it offers considerable insight into their sources. The presence of the proximo-distal distributional gradient is a clear sign that receptive units are involved. The enhancement/suppression effects also confirm the involvement of attention. Finally, left-hand dominance suggests several right-hemisphere processes may be involved, such as spatial and tactile perception, and probably interoception.

Electrodermal responses to words in chronic low back pain patients: a comparison between pain descriptors, other emotional words, and neutral words.

OBJECTIVE: This study examines the electrodermal reactivity of chronic sufferers to emotional words. The hypothesis that patients are over-sensitive to pain descriptors is tested. METHODS: Electrodermal activity was recorded in 12 chronic low back pain patients and 12 healthy controls during passive viewing of words on a video monitor. These words were pain descriptors, other emotional words, and neutral words, in a pseudo-randomized order. A jingle was associated with the word occurrence. RESULTS: In chronic low back pain patients, skin conductance responses (SCRs) induced by pain descriptors or other emotional words were larger than SCRs induced by neutral words but they did not differ from each other. Patients presented SCRs, which were both larger and faster than those of controls, including following neutral words. There was no significant effect of word type in controls. Skin conductance level and the number of nonspecific fluctuations were larger in patients as compared with controls. CONCLUSIONS: The present electrodermal study suggests that chronic pain is linked to an increased reactivity to a wide range of stimuli. Emotional load amplifies the effect. This leads to recommend broad therapeutic management in chronic sufferers. Contrary to expectation derived from classical conditioning, patients did not prove over-sensitive to pain descriptors. This negative finding is discussed at methodologic, physiologic, and psychologic levels.

How to detect an electrocutaneous shock which is not delivered? Overt spatial attention influences decision.

Lateral shifts in overt attention have been previously shown to modulate reaction times to lateral electrocutaneous stimuli, as well as perception or unpleasantness thresholds. A response bias can play a role in the elicitation of these lateral differences. Therefore, the present experiment aimed at investigating whether eye orientation induces a decision bias in favour of the ipsilateral hemispace. Participants were asked whether or not they suspected subliminal electrocutaneous shocks, whereas no subliminal stimulation was actually delivered. A secondary visual task led participants to direct their eyes ipsi- or contralateral to the stimulated area. Differences between experimental conditions in the amount of subliminal shocks participants acknowledge to receive (number of positive responses) are thought to reflect decision biases. Low and high trait anxiety participants were involved. Results showed an interaction between the eye orientation and the tested hand. The number of positive responses was smaller in right-hand tests with contralateral eye orienting. This effect fits those described previously with real electrocutaneous stimuli. This interaction is related to hemispheric differences in spatial attention. In contrast to thresholds studies, this study failed to replicate that a lateral difference arises in the low but not in the high trait anxiety individuals, suggesting that this interaction was mostly due to the neurosensory processing of the electrocutaneous stimuli.

The influence of anxiety on electrodermal responses to distractors.

Contrary to classical expectation, anxiety has been repeatedly observed to be associated with reduced electrodermal activity. This could be the result of successful coping. In line with this interpretation, high-trait anxious individuals performing moderately arousing tasks were expected to manifest a reduced responding to distractors, since this is an adaptive outcome. High- and low-trait anxious participants had to perform a visual search task in a low-stress context. Unrelated neutral and emotional auditory words served as distractors. As a control, neutral and emotional words were also delivered in a no task condition. Skin conductance responses (SCRs) were greater during the task than during the control phase, but in the high anxious group, this increase in SCRs was smaller following emotional distractors than following neutral ones. Moreover, SCRs to both types of words habituated, but the results suggested that only the low-trait anxious participants presented the classical slowing of SCRs habituation when performing the task. All these data are interpreted as an illustration of a resource-based electrodermal inhibition in the high-trait anxious participants. It sustains the idea that mild to moderate anxiety may increase the mastery of situations.

The effect of eye orientation on slowly increasing pain.

The present study investigated the influence of eye orientation upon the experience of pain. Quasi continuous electrocutaneous stimuli which slowly increased in intensity were delivered to 32 healthy females volunteers. Participants were instructed to direct the eyes at locations that were ipsilateral or contralateral to the stimulated hand. Unpleasantness threshold and pain threshold were significantly higher when the eyes were oriented ipsilateral towards the stimulated hand. In a second experiment phase, the pain intensity increased until tolerance. There was no effect of eye orientation upon pain threshold and tolerance. Results of the first experimental part are in line with the counterintuitive idea that selective monitoring reduces pain distress. The lack of significant results in the second experiment phase is discussed in terms of statistical power and a change in coping induced by the expectation of high intensity pain.

Electrodermal activity in low back pain patients with and without co-morbid depression.

Electrodermal activity was examined at rest and during a series of pure innocuous tones in two groups of chronic low back pain patients, one of which consisted of patients suffering also from depression. A group of healthy participants and a group of patients suffering from depression unrelated to pain served as control groups. The non-depressed patients presented an increased electrodermal activity, especially a higher frequency of non-specific fluctuations, as compared to the three other groups. Skin conductance level also appeared lower in the two groups of depressed participants than in the healthy control group. These data show that the EDA recorded in chronic pain patients with and without co-morbid depression must advantageously be analysed separately.

Influence of eye orientation on pain as a function of anxiety.

The effect of eye orientation on pain was investigated as a function of the stimulus intensity and the subjects' anxiety. Right-handed female subjects received sequences of electric shocks gradually increasing in intensity. Unpleasantness threshold, pain threshold, tolerance threshold and pain range were obtained when eyes were directed towards a target LED situated in the direction of, or away from, the source of stimulation, in the ipsi- or contralateral hemispace. Directing the eyes ipsilaterally to the stimulated hand yielded a lower unpleasantness threshold when the right hand was stimulated. No significant effect was observed in high trait anxiety subjects. These results are interpreted in terms of hemispatial attention bias. Moreover, an ipsilateral eye orientation increased pain range but this effect reversed in the highest state anxiety subjects. These latter observations could reflect the interacting influences of both spatial attention and state anxiety in selecting the processing mode of painful stimuli.