Search

Organized neuronal activity underlies brain functioning. Both information processing and transmission between cortical structures occur due to synchronized neuronal activity. In the awake state, one of the mechanisms contributing to integration and synchronization of cortical activity between functionally linked parts of the central nervous system is sensory input. The state of deep anesthesia or deep sleep is also characterized by the presence of organized neural activity—slow oscillations (SO). However, under these states, the central nervous system is considered to be sensory deprived. While SOs have a high level of synchronization between different cortical areas, little is known about the mechanisms that coordinate MOs during sleep or anesthesia. Using methods of electrophysiological recording of neocortex activity in a in vivo model, we show that during deep anesthesia, SOs in different parts of the neocortex are synchronized by breathing. Despite the different frequencies of SOs and breathing, we found a phase-lock of episodes of cortical activity to breathing. The highest probability of periods of cortical activity is observed during the exhalation phase of the anesthetized animal, while the inhalation is accompanied by a decrease in cortical activity. Our results, show that breath plays the role of a driver of the rhythm of cortical activity at a time when the neocortex is restricted in receive of an external synchronizing stimulus. [ABSTRACT FROM AUTHOR]

The present study aimed to identify whether or not the release of interleukin (IL)-6 and soluble (s) IL-6 receptor (R) is associated with fatiguing behaviour and changes in cortical activity during self-paced exercise. Relationships between the IL-6 and its soluble receptors, total work, reductions in power output, and changes in slow, alpha (α) and fast, beta (β) brain waves during self-paced exercise were evaluated. Different intensities and environments were used to manipulate the release of IL-6, whereby seven active males cycled for 60 min in heat stress (HS) or thermoneutral (TN) environments at a clamped rating of perceived exertion (RPE) equating to low intensity (RPE = 12) or high intensity (RPE = 16). IL-6 and sIL-6R were positively associated with total work, but not with reductions in power output. There was greater α activity in high-intensity conditions, which was associated with the reduction in power output. Both high-intensity conditions appeared to have greater β activity, and there was a positive correlation between β activity and total work and β activity and sIL-6R. We conclude that IL-6 and sIL-6R may contribute to perturbations in cortical activity and are associated with total work output, but reductions in power output are likely influenced greater by other internal and external factors. [ABSTRACT FROM AUTHOR]

The aim of this exploratory cross-sectional study was to investigate the characteristics of cortical activity and stress coping in migraine patients, meditation experienced subjects, and healthy controls. 45 meditation experienced subjects, 46 migraine patients, and 46 healthy controls took part in the study. Cortical activity was measured with the contingent negative variation (CNV), a slow cortical event-related potential. Stress coping was examined with the standardized Stress Coping Questionnaire SVF-78. A one-way analysis of variance was used to investigate possible differences between the groups. CNV-amplitude was significantly higher in migraineurs than in controls. The meditators showed significantly lowest amplitudes. Migraine patients used negative stress-coping strategies significantly more often than meditators and healthy controls. Especially the application of the strategy 'rumination' was most frequent in migraine patients and least frequent in meditators. Moreover, frequent rumination was significantly correlated with high CNV-amplitudes. Cortical and stress processing in people with meditation experience was improved compared to migraine patients and healthy controls. [ABSTRACT FROM AUTHOR]

Objective: Obesity is an established risk factor for impaired cognition, which is primarily regulated by the prefrontal cortex (PFC). However, very little is known about the neural pathways that underlie obesity-related declines in neuromuscular control, particularly under stress. The purpose of this study was to determine the role of the PFC on neuromuscular control during handgrip exertions under stress with obesity.Methods: Twenty non-obese and obese young adults performed submaximal handgrip exertions in the absence and presence of a concurrent stressful task. Primary dependent measures included oxygenated hemoglobin (HbO2: a measure of PFC activity) and force fluctuations (an indicator of neuromuscular control).Results: Higher HbO2 levels in the PFC were observed in the non-obese compared to the obese group (P = 0.009). In addition, higher HbO2 levels were observed in the stress compared to the control condition in the non-obese group; however, this trend was reversed in the obese group (P = 0.043). In general, force fluctuations increased by 26% in the stress when compared to the control condition (P = 0.001) and obesity was associated with 39% greater force fluctuation (P = 0.024). Finally, while not significant, obesity-related decrements in force fluctuations were magnified under stress (P = 0.063).Conclusion: The current study provides the first evidence that neuromuscular decrements with obesity were associated with impaired PFC activity and this relationship was augmented in stress conditions. These findings are important because they provide new information on obesity-specific changes in brain function associated with neuromuscular control since the knowledge previously focused largely on obesity-specific changes in peripheral muscle capacity. [ABSTRACT FROM AUTHOR]

Moxibustion is under active research as a complementary and alternative treatment for various diseases such as pain. 'Heat-sensitization' responses have been reported during suspended moxibustion, whose occurrence is associated with significantly better therapeutic effects. The present study aimed to investigate the cortical activities of this interesting phenomenon by a standardized low-resolution brain electromagnetic tomography. We performed electroencephalography recording in a group of patients with chronic low back pain before, during, and after moxibustion treatment at Yaoyangguan (DU3) areas. 11 out of 21 subjects experienced strong heat-sensitization during moxibustion, which were accompanied with significant decreases of current densities in the beta frequency bands in prefrontal, primary and second somatosensory, and cingulate cortices, as well as increased current densities in the alpha2 band in the left insula. No changes were detected in patients without sensitization responses, or in the post-moxibustion phase of either group. These data indicated widespread activity changes across different frequency bands during heat-sensitization. Cortical oscillatory activities could be used to evaluate the 'heat-sensitization' responses during suspended moxibustion. [ABSTRACT FROM AUTHOR]

The study used a dual-task (DT) postural paradigm (two tasks performed at once) that included electroencephalography (EEG) to examine cortical interference when a visual working memory (VWM) task was paired with a postural task. The change detection task was used, as it requires storage of information without updating or manipulation and predicts VWM capacity. Ground reaction forces (GRFs) (horizontal and vertical), EMG, and EEG elements, time locked to support surface perturbations, were used to infer the active neural processes underlying the automatic control of balance in 14 young adults. A significant reduction was seen between single task (ST) and DT conditions in VWM capacity ( F(1,13) = 6.175, p < 0.05, r = 06) and event-related potential (ERP) N1 component amplitude over the L motor ( p < 0.001) and R sensory ( p < 0.05) cortical areas. In addition, a significant increase in the COP trajectory peak (pkcopx) was seen in the DT versus ST condition. Modulation of VWM capacity as well as ERP amplitude and pkcopx in DT conditions provided evidence of an interference pattern, suggesting that the two modalities shared a similar set of attentional resources. The results provide direct evidence of the competition for central processing attentional resources between the two modalities, through the reduction in amplitude of the ERP evoked by the postural perturbation. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the present study was to evaluate the short-term effects of the vision trainer rehabilitation technique on retinal and post-retinal function in young amblyopic patients outside the critical visual developmental period. Methods: Twenty-one patients (mean age 12.2 ± 2.7 years, ranging from 9.1 to 18 years) affected by unilateral anisometropic amblyopia were studied, providing 21 amblyopic eyes (AE) and 21 sound eyes (SE). Thirty eyes from 15 age-similar normal subjects served as controls. All subjects underwent extensive ophthalmologic characterization to exclude any disease not related to amblyopia. All AE were subjected to rehabilitation sessions performed by the Retimax vision trainer (VT) program. The protocol consisted of 2 sessions per week, each lasting 10 min, for 10 consecutive weeks. Before and after the rehabilitation, electrophysiological [pattern electroretinogram (PERG) and visual evoked potential (VEP)] and psychophysical [best corrected visual acuity (BCVA) and microperimetry] data were collected from AE and SE. Results: When comparing baseline data with those collected at the end of the study, PERG P50-N95 amplitude and BCVA values from AE had improved significantly by the end of the study ( p < 0.05). Our electrophysiological findings also showed some abnormalities in SE when the data were compared to control eyes. We found a significant correlation ( p < 0.05) between PERG amplitude and VEP implicit time in SE after visual rehabilitation. Conclusions: Short-term visual rehabilitation performed by the VT program ameliorated the electrofunctional and psychophysical parameters of vision in children outside the critical developmental period, thus indicating that VT might be a potential adjuvant therapy of traditional patching treatment. [ABSTRACT FROM AUTHOR]

This review addresses studies seeking experimental confirmation of the author's visceral theory of sleep, along with independent investigations whose results are consistent with this hypothesis. The visceral hypothesis suggests that during sleep, the central nervous system, particularly the cerebral cortex, switches from analyzing exteroceptive information to analyzing signals arriving from interoceptors distributed throughout all the systems of the body. Substitution of cortical afferentation during sleep implies a simultaneous substitution in the targeting of efferent cortical information streams. In waking, these streams are directed to structures supporting behavior in the environment. During sleep, they switch to structures supporting the efficient operation of all the visceral systems. Analysis of the visceral hypothesis of sleep shows that many pathological states associated with the sleep-waking cycle can be explained in terms of impairments to the synchronicity of the switching of information streams in the cerebral cortex going from waking from sleep and vice versa. [ABSTRACT FROM AUTHOR]

This review discusses data from experimental studies and population observations providing evidence that impairments to the natural sleep regime and decreases in the total duration of sleep lead to the onset of pathological changes in the functioning of the body's autonomic systems. The consequences of sleep impairment in relation to the functioning of the gastrointestinal tract and cardiovascular, respiratory, immune, endocrine, and reproductive systems are discussed briefly. With the aim of explaining the physiological mechanisms linking the state of the body's visceral systems with sleep, we propose the hypothesis that during sleep, the central nervous system, in particular the cerebral cortex, switches its analysis from exteroceptive to interoceptive information. A selection of studies is presented supporting this point of view with direct experimental data. [ABSTRACT FROM AUTHOR]

The aim of this study was to study if accuracy in sensorimotor control and cortical activity was influenced after induced fatigue during a knee joint reproduction task. Twelve volunteers performed a sensorimotor task before, directly after and 60 min after a prolonged exhaustive exercise protocol. The task consisted of an active reproduction of a target knee angle. After three practice trials, visual feedback was taken and the task was performed for 10 repetitions at a suitable pace. Reproduction accuracy was analyzed and EEG raw data were obtained from the frontal, central, temporal, parietal and occipital scalp locations during the task. The average power spectra in theta and alpha frequencies were computed across conditions for each participant. Task accuracy decreases significantly related to fatigue and increases after recovery. This is accompanied by a significant decrease in frontal theta, alpha-1 and alpha-2 frequencies after inducing fatigue. The power values in all frequency bands recovered after 60 min. Sensorimotor control was influenced by induced fatigue, which could be demonstrated in behavior and brain activity. Characteristics of brain activity demonstrated an increase in theta and a decrease in alpha-1 and alpha-2 frequency band power. The changes were discussed related to attentional recourses, alertness and somatosensory information processing mechanisms. [ABSTRACT FROM AUTHOR]

Human gait is a complex process in the central nervous system that results from the integrity of various mechanisms, including different cortical and subcortical structures. In the present study, we investigated cortical activity during lower limb movement using EEG. Assisted by a dynamic tilt table, all subjects performed standardized stepping movements in an upright position. Source localization of the movement-related potential in relation to spontaneous EEG showed activity in brain regions classically associated with human gait such as the primary motor cortex, the premotor cortex, the supplementary motor cortex, the cingulate cortex, the primary somatosensory cortex and the somatosensory association cortex. Further, we observed a task-related power decrease in the alpha and beta frequency band at electrodes overlying the leg motor area. A temporal activation and deactivation of the involved brain regions as well as the chronological sequence of the movement-related potential could be mapped to specific phases of the gait-like leg movement. We showed that most cortical capacity is needed for changing the direction between the flexion and extension phase. An enhanced understanding of the human gait will provide a basis to improve applications in the field of neurorehabilitation and brain–computer interfaces. [ABSTRACT FROM AUTHOR]

A 46-year-old man was diagnosed clinically brain dead after sustaining head trauma. The patient was in deep coma, brain nerves were unresponsive and spontaneous breathing was absent. However, EEG showed well preserved activity, but no reactivity to external stimuli. EEG activity disappeared within 40 h. BAEP were highly abnormal, flash-VEP as recorded 3 h after the diagnosis of brain stem death was of high amplitude but of simplified form. The neurophysiological findings revealed that the main reason for deep coma was brain stem damage while cortical activity was still present. This condition raises ethical questions when brain death is diagnosed clinically prior to removal of organs for transplantation. [ABSTRACT FROM AUTHOR]