Neuromagnetic Changes of Brain Rhythm Evoked by Intravenous Olfactory Stimulation in Humans

Summary: To identify the changes in the respective frequency band and brain areas related to olfactory perception, we measured magnetoencephalographic (MEG) signals before and after instilling intravenously thiamine propyl disulfide (TPD) and thiamine tetrahydrofurfuryl disulfide monohydrochloride (TTFD), which evoked a strong and weak sensation of odor, respectively. For the frequency analysis of MEG, a beamformer program, synthetic aperture magnetometry (SAM), was employed and event-related desynchronization (ERD) or synchronization (ERS) was statistically determined. Both strong and weak odors induced ERD in (1) beta band (13–30 Hz) in the right precentral gyrus, and the superior and middle frontal gyri in both hemispheres, (2) low gamma band (30–60 Hz) in the left superior frontal gyrus and superior parietal lobule, and the middle frontal gyrus in both hemispheres, and (3) high gamma band 2 (100–200 Hz) in the right inferior frontal gyrus. TPD induced ERD in the left temporal, parietal and occipital lobes, while TTFD induced ERD in the right temporal, parietal and occipital lobes. The results indicate that physiological functions in several regions in the frontal lobe may change and the strength of the odor may play a different role in each hemisphere during olfactory perception in humans. This study was supported by Japan Space Forum, Grant-in-Aid for Scientific Research on Priority Areas -Higher-Order Brain Functions-from The Ministry of Education, Culture, Sports, Science and Technology, Japan.     

Compensatory Increase of the Cervico-Ocular Reflex with Age in Healthy Humans

The cervico-ocular reflex (COR) is an ocular stabilization reflex that is elicited by rotation of the neck. It works in conjunction with the vestibulo-ocular reflex (VOR) and the optokinetic reflex (OKR) in order to prevent visual slip over the retina due to self-motion. The gains of the VOR and OKR are known to decrease with age. We have investigated whether the COR, a reflexive eye movement elicited by rotation of the neck, shows a compensatory increase and whether a synergy exists between the COR and the other ocular stabilization reflexes. In the present study 35 healthy subjects of varying age (20–86 years) were rotated in the dark in a trunk-to-head manner (the head fixed in spaced with the body passively rotated under it) at peak velocities between 2.1 and 12.6 deg s⁻¹ as a COR stimulus. Another 15 were subjected to COR, VOR and OKR stimuli at frequencies between 0.04 and 0.1 Hz. Three subjects participated in both tests. The position of the eyes was recorded with an infrared recording technique. We found that the COR-gain increases with increasing age and that there is a significant covariation between the gains of the VOR and COR, meaning that when VOR increases, COR decreases and vice versa. A nearly constant phase lag between the COR and the VOR of about 25 deg existed at all stimulus frequencies.     

颈椎病患者短潜时体感诱发电位的初步研究

为探讨短潜时体感诱发电位对颈椎病诊断的意义，检测了15例颈椎病患的短潜时体感诱发电位(SSEP)，并与对照组比较。结果表明：颈椎病患SSEP的N20、P25波潜伏期及N13-N20峰间潜伏期(即中枢神经传导时间，CCT)和N13-P25峰间潜伏期均比对照组明显延长，其SSEP异常率为73，3％。提示短潜时体感诱发电位检查能客观评价颈椎病患的神经功能，有助于评价疗效和判断预后。     

体感诱发电位检测中经皮电极下电刺激分布模型的研究

体感诱发电位是检测脊神经和周围神经活动的重要方法,而经皮电刺激是体感诱发电位检测中的应用手段,通过对经皮刺激电极下电势场和电流密度场的分布的研究,可以提高检测的效率与质量。我们采用镜像法,对经皮刺激电极下人体组织中电位场和电流密度场的分布进行了理论的推导,得到了场分布的解析解,以此解析解为基础,就可以得到电极放置位置下场分布的数值解,为临床神经刺激提供理论指导。     

SEP联合MEP监测在颅内动脉瘤夹闭术中的应用研究

目的 分析在接受颅内动脉瘤夹闭术患者中使用体感诱发电位和经颅电刺激运动诱发电位联合监测进行手术监测的效果。方法 回顾分析2014年12月~2015年12月我院收治的90例接受颅内动脉瘤夹闭术的患者作为研究对象,将其分对照组与观察组,各45例,对照组患者不采用电生理监测,观察组患者使用SEP与MEP联合监测,对比两组患者的术后效果及相应指标。结果 术后,观察组患者重度瘫痪率、术后并发症率、再手术率以及住院天数均低于或少于对照组,差异有统计学意义（P＜0.05）。结论 颅内动脉瘤夹闭术患者使用SEP与MEP联合监测对于提高术中指导水平及术后恢复质量均具有积极意义,同时可降低术后缺血性脑卒中发生率,应用价值较高。     

Reflex Plasma Hyperglycemia and Hyperosmolality Evoked by Unloading of the Carotid Baroreceptors

Hemorrhage is usually accompanied by a considerable increase in the plasma osmolality and glucose concentration due to an augmented release of glucose from the liver. In the present cat experiments an attempt was made to investigate the possible role of different vascular receptors in mediating this hyperglycemic (hyperosmolar) response. Bilateral vagotomy or stimulation of the carotid chemoreceptors by perfusion of the carotid sinus with venous blood at normal pressure only slightly increased the arterial plasma glucose concentration. On the other hand, when the sinus nerves were cut in the vagotomized animal, thereby simulating complete unloading of the carotid baroreceptors, the arterial plasma glucose concentration rose by about 8 mM/L and the arterial plasma osmolality by about 10 mOsm/kg H₂O. Perfusion of the carotid baroreceptors with arterial blood at different levels of hypotension showed that the baroreceptor-induced hyperglycemia was graded in relation to the pressure level. Regional hypotension of the liver, pancreas, intestine, kidneys or brain did not significantly affect plasma glucose concentration or osmolality. We conclude that the reflex release of glucose from the liver during hemorrhage mainly is initiated from the unloading of arterial baroreceptors.     

Cortical Potentials Evoked in Humans by Signals to Perform Memory-Guided Saccades

Increases in the latent periods of memory-guided saccades as compared with those of visually guided saccades were observed, providing evidence of slowing in saccade programming based on extraction of information from working memory. Comparison of the parameters and topography of the N1 and P1 components of evoked potentials induced by a signal to perform a memory-guided saccade and a visual stimulus-guided saccade suggested that the early stages of saccade programming, associated with the processing of spatial information, are mediated mainly by the descending mechanism of attention for memory-guided saccades and the ascending mechanism for saccades in response to a visual stimulus. These data may indicate that the increase in the latent period of memory-guided saccades is associated with lengthening of the central stage of saccade programming – the decision-taking stage, a correlate of which is the N2 wave developing in the middle of the latent period of the memory-guided saccade. The temporospatial dynamics of the N1, P1, and N2 components provide evidence that memory-guided saccade programming is controlled by the fronto-medio-thalamic system of selective attention, as well as by left-hemisphere motor attention mechanisms.     

Studies of Interactions between Limbs in Humans Subjected to Noninvasive Electrical Stimulation of the Spinal Cord

Neuroscience and Behavioral Physiology - The effects of activation of spinal locomotor centers at the cervical and lumbar levels on interlimb synergies were studied in humans. Subjects were placed...     

Amplitude and Latency Changes in the Visual Evoked Potential to Different Stimulus Intensities

Visual evoked potentials (VEPs) were recorded from five sites (T₃, T₄, C_z, O₁, O₂) to six intensities of light flashes. Peak-to-trough amplitudes were measured for the P100-N120 and N120-P200 waveforms as well as baseline (prestimulus)-to-peak amplitudes for each component (i.e. P100, N120, and P200). Different methods of defining augmenting/reducing were compared. These included subtracting the VEP epoch mean level from mean levels within a timeband corresponding to P100 and calculating slopes both for these values and for the P100-N120 amplitudes across intensities. The technique of using slopes to describe amplitude-intensity functions was found to be unjustified and misleading. The Augmenting/Reducing groups defined by the slopes of peak-to-trough amplitudes or slopes of the timeband “amplitudes” proved to be almost mutually exclusive. Results also showed that the frequency with which actual VEP peaks occur within the appropriate timeband is very low and differs topographically. Augmenting/Reducing was then defined by monotonic increases in the P100-N120 peak-to-trough amplitudes. Augmenters and Reducers differed from each other not only for amplitude-intensity patterns but on a number of latency measures. Hemisphere differences were also found between groups. An inverse relationship was found between occipital and vertex amplitude-intensity patterns such that vertex augmenting was accompanied by occipital reducing and vice versa. Temporal and vertex amplitude-intensity patterns were similar.     

Instrumentalization of Movements Evoked by Stimulation of the Motor Cortex by Food Reinforcement in Dogs

The possibility that hindlimb movements (elevations) evoked by stimulation of the corresponding contralateral area of the motor cortex could be instrumentalized by reinforcement with food was demonstrated, contradicting some previously published data. Operant movements (interstimulus voluntary high elevations of the hindlimb) were acquired as a result of consistent combinations: cortical stimulation – movement – food. Acquisition required more than 50–200 combinations. Delivery of food was accompanied by a click at exactly the moment at which the hindlimb reached the required height. The click became the food-related conditioned signal and served as a secondary operant reinforcement, which facilitated acquisition of the operant movement. These results support the view that the motor cortex can have an immediate role in forming operant temporary connections (motivation-movement) and that simple operant movements can be initiated via this arc.     

Acromiohumeral Distance During Neuromuscular Electrical Stimulation of the Lower Trapezius and Serratus Anterior Muscles in Healthy Participants

Context

Compromise to the acromiohumeral distance has been reported in participants with subacromial impingement syndrome compared with healthy participants. In clinical practice, patients with subacromial shoulder impingement are given strengthening programs targeting the lower trapezius (LT) and serratus anterior (SA) muscles to increase scapular posterior tilt and upward rotation. We are the first to use neuromuscular electrical stimulation to stimulate these muscle groups and evaluate how the muscle contraction affects the acromiohumeral distance.

Objective

To investigate if electrical muscle stimulation of the LT and SA muscles, both separately and simultaneously, increases the acromiohumeral distance and to identify which muscle-group contraction or combination most influences the acromiohumeral distance.

Design

Controlled laboratory study.

Setting

Human performance laboratory.

Patients or Other Participants

Twenty participants (10 men and 10 women, age = 26.9 ± 8.0 years, body mass index = 23.8) were screened.

Intervention(s)

Neuromuscular electrical stimulation of the LT and SA.

Main Outcome Measure(s)

Ultrasound measurement of the acromiohumeral distance.

Results

Acromiohumeral distance increased during contraction via neuromuscular electrical stimulation of the LT muscle (t₁₉ = −3.89, P = .004), SA muscle (t₁₉ = −7.67, P = .001), and combined LT and SA muscles (t₁₉ = −5.09, P = .001). We observed no differences in the increased acromiohumeral distance among the 3 procedures (F_2,57 = 3.109, P = .08).

Conclusions

Our results supported the hypothesis that the muscle force couple around the scapula is important in rehabilitation and scapular control and influences acromiohumeral distance.Key Words: subacromial impingement syndrome, real-time ultrasound, rehabilitation

Key Points

• Acromiohumeral distance increased during neuromuscular electrical stimulation of the lower trapezius muscle, serratus anterior muscle, and combined lower trapezius and serratus anterior muscles.
• The increase in acromiohumeral distance was not different among the 3 neuromuscular electrical-stimulation procedures.
• The muscle force couple around the scapula is important in rehabilitation and scapular control and influences acromiohumeral distance.

Optimal upper limb function depends on the ability to statically and dynamically position the shoulder girdle in an optimal coordinated fashion.^1,2 Suboptimal motor control is considered a risk factor for developing shoulder subacromial impingement syndrome.^3–14 Alterations in scapular motion have been linked to a decrease in serratus anterior (SA) muscle activity, an increase in upper trapezius muscle activity, and an imbalance of forces between the upper and lower parts of the trapezius muscle.¹⁵ This may adversely affect scapular positioning, resulting in reduced scapular upward rotation, increased anterior scapular tilt, and scapular winging.^4,9,16 In turn, scapular upward rotation and posterior tilt are considered vital for elevating the acromion and, hence, widening the subacromial space, thereby preventing impingement of the subacromial tissues.^17,18 Atalar et al¹⁹ suggested that reduced scapular mobility led to a decrease in acromiohumeral distance (AHD) during upper extremity abduction. Therefore, when developing rehabilitation strategies for patients with subacromial impingement syndrome, correcting neuromuscular control of the SA and trapezius muscles is important.^20,21Overall, researchers^22,23 have supported the theory that altered activity in the scapular rotator muscles is present in patients with subacromial impingement syndrome and have highlighted the role of scapular rotator muscle training as an essential component of shoulder rehabilitation. A clinical practice strategy, supported by research data, recommends that patients who have subacromial shoulder impingement and present with primary movement dysfunction of the scapula should be given strengthening programs targeting the lower trapezius (LT) and SA muscles.^24,25 The LT muscle is reported to increase posterior scapular tilt, and the SA muscle is believed to increase upward rotation of the scapula.² In turn, posterior scapular tilt and upward scapular rotation are associated with increased AHD.^17,18Authors^9,23,26–29 of electromyographic (EMG) studies have tested muscle activity in participants with subacromial impingement syndrome and in healthy persons. In patients with subacromial impingement syndrome, when the upper extremity was at rest and during flexion and abduction, the EMG signal amplitude of the upper trapezius muscle increased, whereas the EMG signal amplitude of the LT and SA muscles decreased.^30,31 These researchers have considered the immediate changes in the surface EMG activity of the scapular rotator muscles. However, to our knowledge, we are the first to use neuromuscular electrical stimulation (NMES) to stimulate the muscle groups of the LT and SA and evaluate the effect of muscle contraction in these muscles on the AHD. Neuromuscular electrical stimulation is used for various medical applications and is a common intervention during rehabilitation to improve function and motor control,³² prevent and treat shoulder pain,³³ increase range of motion,³⁴ and facilitate changes in muscle action and performance.³⁵ Therefore, the purpose of our study was to investigate whether stimulation of the LT and the SA muscles (separately and simultaneously) with NMES would increase the AHD and to investigate which muscle-group contraction or combination most influenced the AHD.     

Changes in Evoked Potentials on Increases in the Difficulty of Visual Searches in Humans

Monopolar evoked potentials (EP) in the frontal, parietal, temporal, and occipital leads in 16 young healthy subjects were analyzed during visual searches of increasing difficulty. Increases in the complexity of the visual search and addition of “noise” to visual stimuli added significant difficulty to the image recognition task, which was reflected in increases in search times and errors. Correlation of changes in EP and search parameters was seen mainly in the frontal leads: there were significant positive relationships between the N2 and P4 components and the SN–SP difference wave on the one hand and search difficulty on the other; there was a negative relationship with the P3 component, probably due to an increase in the duration and amplitude of the preceding N2 component. The N2 and P4 components were most marked in the frontal leads. We suggest that these data provide evidence of increasing dominance of frontal structures in the attention control system as the visual task increases in difficulty.     

诱发电位潜伏期变化检测中基于谱函数特性分析的参考信号构造方法

诱发电位信号潜伏期变化的自适应检测对于诊断中枢神经系统的损伤和病变具有重要的意义。在以往的潜伏期变化估计算法中，往往采用通过累加平均的方法得到的近似纯净的EP信号作为自适应时间延迟估计的参考信号。而在临床上。无潜伏期延迟的纯净EP信号是很难得到的。本研究提出了一种基于信号谱函数分析的EP信号构造方法，并将此信号作为参考信号，应用到诱发电位信号潜伏期变化估计中去，得到了良好的结果。     

Fear-Potentiated Startle in Humans: Effects of Anticipatory Anxiety on the Acoustic Blink Reflex

The effects of fear/anticipatory anxiety on the acoustic startle reflex were investigated in humans using a paradigm involving anticipation of electric shocks. The eyeblink component of the startle reflex, elicited by an abrupt auditory stimulus, was measured in 9 normal volunteers during either the anticipation of electric shocks (anticipatory anxiety) or periods in which no shocks were anticipated (safe period). The eyeblink was consistently higher in amplitude, and shorter in latency, during periods when the subjects anticipated shocks, compared to the safe periods. This effect could not be attributed solely to a reduction in habituation and was statistically significant before the subjects actually received any shock (a single 30 mA stimulation on the median nerve). These results indicate that anticipatory anxiety can be measured objectively in humans using the fear-potentiated startle reflex in a paradigm not actually requiring any shock. Because a great deal is known about the neuroanatomical and pharmacological mechanisms of fear-potentiated startle in laboratory animals, this test procedure may be especially useful in humans to investigate the neurobiological substrates of anxiety disorders and their pharmacological treatments.     

The Effect of an Acoustic Warning Stimulus Upon the Electrically Elicited Blink Reflex in Humans

In a warned Go/No-Go reaction time experiment blink reflexes were elicited electrically immediately before, at, and shortly after the onset of a low intensity acoustic warning stimulus. This provided the opportunity to study the mutual effects of two stimuli of different modalities arriving at the facial nucleus. The warning stimulus was followed after 3 s by an acoustic response stimulus. Sixteen subjects participated in the experiment. They were informed by the response stimulus if a response (a voluntary blink of the right eye) was required. R1 magnitude was increased from 10 ms to 100 ms after warning stimulus onset, with a pronounced peak at 50 ms. The bilateral late component R2 was enhanced when the reflex eliciting stimulus preceded the warning stimulus. Between 20 ms and 30 ms after warning stimulus onset, R2 returned to control level, whereas an eliciting stimulus presented 40 ms or later after warning stimulus onset produced a pronounced inhibition. R2 latency was facilitated immediately after warning stimulus onset. It was concluded that the mutual effects of stimuli of different modalities can be interpreted only if the moment of arrival at the motor nucleus is taken into consideration.     

Pharmacological Modulation of Cortical Excitability Shifts Induced by Transcranial Direct Current Stimulation in Humans

Transcranial direct current stimulation (tDCS) of the human motor cortex results in polarity-specific shifts of cortical excitability during and after stimulation. Anodal tDCS enhances and cathodal stimulation reduces excitability. Animal experiments have demonstrated that the effect of anodal tDCS is caused by neuronal depolarisation, while cathodal tDCS hyperpolarises cortical neurones. However, not much is known about the ion channels and receptors involved in these effects. Thus, the impact of the sodium channel blocker carbamazepine, the calcium channel blocker flunarizine and the NMDA receptor antagonist dextromethorphane on tDCS-elicited motor cortical excitability changes of healthy human subjects were tested. tDCS-protocols inducing excitability alterations (1) only during tDCS and (2) eliciting long-lasting after-effects were applied after drug administration. Carbamazepine selectively eliminated the excitability enhancement induced by anodal stimulation during and after tDCS. Flunarizine resulted in similar changes. Antagonising NMDA receptors did not alter current-generated excitability changes during a short stimulation, which elicits no after-effects, but prevented the induction of long-lasting after-effects independent of their direction. These results suggest that, like in other animals, cortical excitability shifts induced during tDCS in humans also depend on membrane polarisation, thus modulating the conductance of sodium and calcium channels. Moreover, they suggest that the after-effects may be NMDA receptor dependent. Since NMDA receptors are involved in neuroplastic changes, the results suggest a possible application of tDCS in the modulation or induction of these processes in a clinical setting. The selective elimination of tDCS-driven excitability enhancements by carbamazepine proposes a role for this drug in focussing the effects of cathodal tDCS, which may have important future clinical applications.