Search results for "Stimulus"
showing 10 items of 555 documents
Towards real-time detection of cognitive effort in driving: Contribution of cardiac measurement
2016
En 2013, on estime que 40 à 50% des accidents corporels seraient dus à des défauts d'attention de la part du conducteur. Des études récentes ont mis en évidence la possibilité de détecter des états attentionnels dégradés afin de pouvoir mieux assister le conducteur ; ce thème de recherche représente donc un nouveau gisement de sécurité routière. Cette étude se concentre sur la détection de l'effort cognitif fournit par les conducteurs et cherche, par l'étude de la variation du rythme cardiaque, à identifier un indicateur d'effort sensible sur de courtes fenêtres temporelles.Chacun des 18 participants a passé 8 conditions expérimentales sur simulateur de conduite : la moitié où seule une tâc…
Uncontrolled immune response in acute myocardial infarction
2008
Recently, the theory that hyperinflammation is the body's primary response to potent stimulus has been challenged. Indeed, a deregulation of the immune system could be the cause of multiple organ failure. So far, clinicians have focused on the last steps of the inflammatory cascade. However, little attention has been paid to lymphocytes, which play an important role as strategists of the inflammatory response. Experimental evidence suggests a crucial role of T lymphocytes in the pathophysiology of atherosclerosis and acute myocardial infarction (AMI). In summary, from the bottom of an imaginary inverted pyramid, a few regulatory T-cells control the upper parts represented by the wide spectr…
Secondary hyperalgesia to punctate mechanical stimuli
1999
Tissue injury induces enhanced pain sensation to light touch and punctate stimuli in adjacent, uninjured skin (secondary hyperalgesia). Whereas hyperalgesia to light touch (allodynia) is mediated by A-fibre low-threshold mechanoreceptors, hyperalgesia to punctate stimuli may be mediated by A- or C-fibre nociceptors. To disclose the relative contributions of A- and C-fibres to the hyperalgesia to punctate stimuli, the superficial radial nerve was blocked by pressure at the wrist in nine healthy subjects. Secondary hyperalgesia was induced by intradermal injection of 40 microg capsaicin, and pain sensitivity in adjacent skin was tested with 200 micron diameter probes (35-407 mN). The progress…
The Temporal Development of Early and Late CNV in a Simple Discrimination Paradigm: the Effects of Motor Preparation and Average Reaction Time
1980
Publisher Summary This chapter discusses the temporal development of early and late contingent negative variation (CNV) in a simple discrimination paradigm. The CNV typically arises when a warning stimulus is paired with an imperative stimulus which, in turn, is followed by a motor reaction. If the interstimulus interval is less than approximately 2 sec the CNV begins immediately after the positive deflection (P300) following the warning stimulus. It may appear as a steadily rising negative potential shift that reaches its peak with the presentation of the imperative stimulus, or as sustained negativity throughout the rest of the foreperiod. If the interstimulus interval is extended beyond …
Early cortical processing of vection-inducing visual stimulation as measured by event-related brain potentials (ERP)
2019
Abstract Visual motion stimuli can induce the perception of self-motion in stationary observers (known as vection). In the present study, we investigated the sensory processing underlying vection by measuring the human event-related brain potentials (ERPs) elicited by the movement onset of a visual stimulus. We presented participants a visual stimulus consisting of alternating black-and-white vertical bars that moved in horizontal direction, creating the sensation of vection. The stimulus was presented on a screen that was divided into a central and a surrounding peripheral visual area. Both areas moved independently from each other, resulting in four different movement patterns: the periph…
Weighted Integration of Duration Information Across Visual and Auditory Modality Is Influenced by Modality-Specific Attention.
2021
We constantly integrate multiple types of information from different sensory modalities. Generally, such integration is influenced by the modality that we attend to. However, for duration perception, it has been shown that when duration information from visual and auditory modalities is integrated, the perceived duration of the visual stimulus leaned toward the duration of the auditory stimulus, irrespective of which modality was attended. In these studies, auditory dominance was assessed using visual and auditory stimuli with different durations whose timing of onset and offset would affect perception. In the present study, we aimed to investigate the effect of attention on duration integr…
Illusory contours and specific regions of human extrastriate cortex: evidence from rTMS
2003
Functional magnetic resonance imaging studies showed that perception of illusory contours is associated with extrastriate cortex activation prevailing on the right side. 1 Hz repetitive transcranial magnetic stimulation (rTMS) is able to induce lasting inhibition of cortical activity. The objective of the study was to investigate the role of extrastriate cortex in illusory contour perception inducing 1 Hz rTMS interference in healthy subjects. Eight healthy subjects underwent 1 Hz rTMS (600 pulses) through a figure-of-eight coil over right and left occipital cortex (O1 and O2 of 10/20 EEG system); sham magnetic stimulation on the same sites and right motor cortex rTMS (in three subjects) we…
Quantifying Intermodal Distraction by Emotion During Math Performance: An Electrophysiological Approach
2019
Emotionally engaging stimuli are powerful competitors for limited attention capacity. In the cognitive neuroscience laboratory, the presence of task-irrelevant emotionally arousing visual distractors prompts decreased performance and attenuated brain responses measured in concurrent visual tasks. The extent to which distraction effects occur across different sensory modalities is not yet established, however. Here, we examined the extent and time course of competition between a naturalistic distractor sound and a visual task stimulus, using dense-array electroencephalography (EEG) recordings from 20 college students. Steady-state visual evoked potentials (ssVEPs) were quantified from EEG, e…
Predictors of visually induced motion sickness in women
2019
Abstract Background Visually induced motion sickness (VIMS) is commonly experienced when visual motion information is in conflict with motion information provided by the vestibular system and/or tactile and kinesthetic senses. According to some studies, women experience higher levels of VIMS than men, whereas other studies do not find this to be the case. Hypothesis This study investigated whether gender differences can be attributed to changes in VIMS-susceptibility due to the menstrual cycle and perceived menstrual pain. We hypothesized that higher perceived menstrual pain correlates positively with VIMS susceptibility. Methods We measured the influence of estimated concentrations of four…
Relationship of subjective helplessness and pain perception after electric skin stimuli
2000
Objective and subjective controllability of painful stimuli are important factors in pain perception. The present study investigated direct and indirect effects of uncontrollability on perceived pain intensity in humans. Forty-eight healthy male volunteers participated in a laboratory experiment using a reaction time paradigm to induce controllable or uncontrollable feedback conditions in two randomly selected groups. Under controllable conditions, unpleasant electric skin shocks were applied, only when the actual time exceeded an individual threshold; under uncontrollable conditions, skin shocks were applied randomly using a yoked control design. Subjective helplessness, perceived pain int…