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ABSTRACT: Pain signals threat and initiates motor responses to avoid harm. The transformation of pain into a motor response is thus an essential part of pain. Here, we investigated the neural mechanisms subserving the sensorimotor transformation of pain at the cortical level by using electroencephalography. In a simple reaction time experiment, brief painful stimuli were delivered to the left hand of healthy human subjects who responded with button presses of the right hand. The results show that the simple reaction time task was associated with neuronal responses at delta/theta, alpha/beta, and gamma frequencies. The analysis of the relationship between neuronal activity and response speed revealed that gamma oscillations, which were temporally coupled to the painful stimuli, but not temporally coupled to the motor response, predicted reaction times. Lateralization of gamma oscillations indicates that they originate from motor areas rather than from sensory areas. We conclude that gamma oscillations are involved in the sensorimotor transformation of pain whose efficiency they reflect. We hypothesize that the relationship between stimulus-locked gamma oscillations and reaction times reflects a direct thalamo-motor route of nociceptive information that is central to the biological function of pain.
Journal of Neurophysiology 05/2012; 108(4):1025-31. · 3.32 Impact Factor
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ABSTRACT: Painful stimuli are of utmost behavioral relevance and thereby affect attentional resources. In health, variable effects of pain on attention have been observed, indicating alerting as well as distracting effects of pain. In the human brain, these effects are closely related to modulations of neuronal gamma oscillations. As hypervigilance as an abnormal increase of attention to external stimuli has been implicated in chronic pain states, we assumed both attentional performance and pain-induced gamma oscillations to be altered in patients with fibromyalgia syndrome (FMS). We recorded electroencephalography from healthy subjects (n = 22) and patients with FMS (n = 19) during an attention demanding visual reaction time task. In 50% of the trials we applied painful laser stimuli. The results of self-assessment questionnaires confirm that patients with FMS consider themselves hypervigilant towards pain as compared to healthy controls. However, the experimental findings indicate that the effects of painful stimuli on attentional performance and neuronal gamma oscillations do not differ between patients and healthy subjects. We further found a significant correlation between the pain-induced modulation of visual gamma oscillations and the pain-induced modulation of reaction times. This relationship did not differ between groups either. These findings confirm a close relationship between gamma oscillations and the variable attentional effects of pain, which appear to be comparable in health and disease. Thus, our results do not provide evidence for a behavioral or neuronal manifestation of hypervigilance in patients with FMS.
PLoS ONE 01/2012; 7(4):e35068. · 4.09 Impact Factor
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ABSTRACT: The perception of pain is characterized by its tremendous intra- and interindividual variability. Different individuals perceive the very same painful event largely differently. Here, we aimed to predict the individual pain sensitivity from brain activity. We repeatedly applied identical painful stimuli to healthy human subjects and recorded brain activity by using electroencephalography (EEG). We applied a multivariate pattern analysis to the time-frequency transformed single-trial EEG responses. Our results show that a classifier trained on a group of healthy individuals can predict another individual's pain sensitivity with an accuracy of 83%. Classification accuracy depended on pain-evoked responses at about 8 Hz and pain-induced gamma oscillations at about 80 Hz. These results reveal that the temporal-spectral pattern of pain-related neuronal responses provides valuable information about the perception of pain. Beyond, our approach may help to establish an objective neuronal marker of pain sensitivity which can potentially be recorded from a single EEG electrode.
Cerebral Cortex 07/2011; 22(5):1118-23. · 6.54 Impact Factor
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ABSTRACT: Perception is not a simple reflection of sensory information but varies within and between individuals. This applies particularly to the perception of pain, which, in the brain, is associated with neuronal responses at different frequencies. Here, we show how these different neuronal responses subserve interindividual and intraindividual variations in the perception of identical painful stimuli. A time-frequency analysis of single trial electroencephalographic data indicates that pain-related responses in the theta frequency range but not at higher gamma frequencies code for interindividual variations in the perception of pain. In contrast, both pain-related theta and gamma responses provide different and complementary information on intraindividual variations in the pain experience. We conclude that theta responses reflect rather constant physiological and psychological traits of the individual, whereas gamma responses relate to short-term modulations of the individual's state. These findings reveal how neuronal responses at different frequencies differentially contribute to the translation of sensory information into a subjective percept.
Cerebral Cortex 03/2011; 21(10):2408-14. · 6.54 Impact Factor
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ABSTRACT: Successful behavior requires the attentional selection and preferred processing of behaviorally relevant sensory information. Painful stimuli are of utmost behavioral relevance and can therefore involuntarily affect attentional resources and interfere with ongoing behavior. However, the neuronal mechanisms which subserve the involuntary attentional effects of pain are largely unknown yet. Here, we therefore investigated the neuronal mechanisms of the attentional effects of pain by using electroencephalography during a visual attention task with the concurrent presentation of painful stimuli. Our results confirm that painful and visual stimuli induce gamma oscillations over central and occipital areas, respectively. Pain-induced gamma oscillations were correlated with pain-induced changes in visual gamma oscillations. Behaviorally, we observed variable effects of pain on visual reaction times, yielding an increase of reaction times for some subjects, as well as a decrease of reaction times for others. Most importantly, however, these changes in visual task performance were significantly related to pain-induced changes of visual gamma oscillations. These findings demonstrate that the variable attentional effects of pain are closely related to changes in neuronal gamma oscillations in the human brain. In the hypervigilant state of chronic pain, maladaptive changes in the attentional effects of pain may be associated with abnormal changes in neuronal gamma oscillations. Our findings may thus contribute to the understanding of the neuronal substrates of pain in health and may open a new window towards the understanding of pathological alterations of the pain experience in chronic pain syndromes.
Pain 08/2010; 150(2):302-8. · 5.78 Impact Factor
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ABSTRACT: Few studies investigated the neuropsychological outcome after carotid angioplasty with stent placement (CAS), yielding partially inconsistent results. The present investigation evaluated the effect of CAS in patients with high-grade stenosis and assessed the predictive value of ischemic lesion number for postinterventional cognitive deterioration.
22 patients were tested neuropsychologically before and six weeks after CAS. Cerebral ischemic changes were assessed with diffusion weighted imaging (DWI) prior to and after angioplasty.
Pre- to postinterventional cognitive performance improved significantly in terms of verbal memory (t = -2.30; p<0.05), whereas significant deterioration was noted regarding verbal memory span (t = 2.31; p<0.05). 8 (36%) persons conformed to the criteria of cognitive improvement. 6 patients (27%) were postinterventionally classified as having deficits. Analysis yielded no statistically significant correlations between lesion quantity and cognitive change.
Both improvement and deterioration of cognitive functioning was observed in our collective of patients, leaving the neuropsychological outcome after percutaneous transluminal angioplasty unpredictable in individual cases. The presence of acute ischemic lesions on DWI was found to be not tightly associated with cognitive dysfunction after CAS.
PLoS ONE 01/2009; 4(9):e7001. · 4.09 Impact Factor
