Electrophysiological correlates of the retention of tones differing in timbre in auditory short-term memory

We examined the electrophysiological correlates of retention in auditory short-term memory (ASTM) for sequences of one, two, or three tones differing in timbre but having the same pitch. We focused on event-related potentials (ERPs) during the retention interval and revealed a sustained fronto-central ERP component (most likely a sustained anterior negativity; SAN) that became more negative as memory load increased. Our results are consistent with recent ERP studies on the retention of pitch and suggest that the SAN reflects brain activity mediating the low-level retention of basic acoustic features in ASTM. The present work shows that the retention of timbre shares common features with the retention of pitch, hence supporting the notion that the retention of basic sensory features is an active process that recruits modality-specific brain areas.     

Finding a way in: A review and practical evaluation of fMRI and EEG for detection and assessment in disorders of consciousness

Diagnoses and assessments of cognitive function in disorders of consciousness (DOC) are notoriously prone to error due to their reliance on behavioural measures. As a result, researchers have turned to functional neuroimaging and electrophysiological techniques with the goal of developing more effective methods of detecting awareness and assessing cognition in these patients. This article reviews functional magnetic resonance imaging (fMRI) and electroenchphalography (EEG)-based studies of cognition and consciousness in DOC, including assessment of basic sensory, perceptual, language, and emotional processing; studies for detection of conscious awareness; paradigms for the establishment of communication in the absence of behaviour; and functional connectivity studies. The advantages and limitations of fMRI and EEG-based measures are examined as research and clinical tools in this population and an explanation offered for the rediscovery of the unique advantages of EEG in the study of DOC.     

老年人迟发性癫痫发作53例临床分析

目的　探讨老年人迟发性癫痫的病因、临床特点、脑电图及影像学特征。方法　回顾分析5 3例老年人迟发性癫痫的临床、脑电图及脑CT资料。结果　癫痫发作的可能病因为脑血管病31例,脑外伤7例,脑萎缩7例,脑肿瘤3例,蛛网膜囊肿1例,硬膜下积液1例,颅内感染1例,不明原因2例。临床发作类型为全身性强直 阵挛发作31例,部分性发作发展至全身性发作4例,部分性发作18例。脑电图共查2 1例,其中异常18例(痫样放电2例,其余主要表现为弥漫性或局限性慢波)。脑CT检查5 1例,异常4 9例。结论　老年人迟发性癫痫多数有明确病因。全身性发作是其主要临床发作类型。影像学检查多能发现病灶,以脑叶病变为多。     

慢性疼痛的心理治疗

心理治疗是区别于止痛药、手术和理疗等止痛方法的一种特殊的治疗方法。其目的是减少慢性疼痛患者对止痛治疗的依赖性,减少应用医疗保健系统,最终恢复家庭、工作和社会责任感。     

Scoring accuracy of automated sleep staging from a bipolar electroocular recording compared to manual scoring by multiple raters

Objectives

Electroencephalography (EEG) assessment in research and clinical studies is limited by the patient burden of multiple electrodes and the time needed to manually score records. The objective of our study was to investigate the accuracy of an automated sleep-staging algorithm which is based on a single bipolar EEG signal.

Methods

Three raters each manually scored the polysomnographic (PSG) records from 44 patients referred for sleep evaluation. Twenty-one PSG records were scored by Rechtschaffen and Kales (R&K) criteria (group 1) and 23 PSGs were scored by American Academy of Sleep Medicine (AASM) 2007 criteria (group 2). Majority agreement was present in 98.4% of epochs and was used for comparison to automated scoring from a single EEG lead derived from the left and right electrooculogram.

Results

The κ coefficients for interrater manual scoring ranged from 0.46 to 0.89. The κ coefficient for the auto algorithm vs manual scoring by rater ranged from 0.42 to 0.63 and was 0.61 (group 1, κ = 0.61 and group 2, κ = 0.62) for majority agreement for all studies. The mean positive percent agreement across subjects and stages was 72.6%, approximately 80% for stages wake (78.3%), stage 2 sleep (N2) (80.9%), and stage 3 sleep (N3) (78.1%); the percentage slightly decreased to 73.2% for rapid eye movement (REM) sleep and dropped to 31.9% for stage 1 sleep (N1). Differences in agreement were observed based on raters, obstructive sleep apnea (OSA) severity, medications, and signal quality.

Conclusions

Our study demonstrated that automated scoring of sleep obtained from a single-channel of forehead EEG results in agreement to majority manual scoring are similar to results obtained from studies of manual interrater agreement. The benefit in assessing auto-staging accuracy with consensus agreement across multiple raters is most apparent in patients with OSA; additionally, assessing auto-staging accuracy limited disagreements in patients on medications and in those with compromised signal quality.     

Results of four technical investigations in fifty clinically brain dead patients

Fifty consecutive patients (aged 19–77 years, median 56 years) with primary cerebral diseases and the clinical signs of absent cortical and brainstem function were subjected to electroencephalography (EEG), brainstem acoustic evoked potentials (BAEP), extracranial Doppler ultrasonography (ECD) and arterial digital subtraction angiography (DSA). In the majority of cases the results of the technical tests agreed with the clinical signs and were suggestive of brain death. However, in one patient EEG revealed clear bioelectrical activity. In 6 cases, doubts existed about whether the EEG was isoelectric; in 3 of the 6 cases biological activity might have been present. In 31 of 42 patients ECD showed a typical pattern of intracranial circulatory arrest, in 9 of 42 ECD revealed a pattern suggestive of the cessation of cerebral blood flow. In four patients BAEP recordings compatible with brain death were recorded 2–3 days before intracranial circulatory arrest. In 2 patients with isoelectric EEG and absent BAEP arterial DSA demonstrated residual perfusion. The findings are discussed in view of the conceptional differences concerning brain death. It is concluded that the strict application of the concept of death of the whole brain requires angiographic demonstration of absent intracerebral blood flow.     

Obstructed defaecation: what is the role of rehabilitation?

Aim The study was designed to evaluate the results of rehabilitative treatment in patients suffering from obstructed defaecation. Method Between January 2008 and July 2010, 39 patients (37 women, age range 25–73 years; and two men, aged 57 and 67 years) affected by obstructed defaecation were included in the study. After a preliminary clinical evaluation, including the Obstructed Defaecation Syndrome (ODS) score, defaecography and anorectal manometry were performed. All 39 patients underwent rehabilitative treatment according to the ‘multimodal rehabilitative programme’ for obstructive defaecation. At the end of the programme, all 39 patients were reassessed by clinical evaluation and anorectal manometry. Postrehabilition ODS scores were used to categorize patients arbitrarily into three classes, as follows: class I, good (score ≤ 4); class II, fair (score > 4 to ≤ 8); and class III, poor (score > 8). Results After rehabilitation, there was significant improvement in the overall mean ODS score (P < 0.001). Thirty (76.9%) patients were included as class I (good results), of whom eight (20.5%) were symptom free. Five (12.8%) patients were considered class III. A significant postrehabilitative direct correlation was found between ODS score and pelvic surgery (ρ_s = 0.54; P < 0.05). Significant differences were found between pre‐ and postrehabilitative manometric data from the straining test (P < 0.001), duration of maximal voluntary contraction (P < 0.001) and conscious rectal sensitivity threshold (P < 0.02). Conclusion After rehabilitation, some patients become symptom free and many had an improved ODS score.     

Brain activity in near-death experiencers during a meditative state

Aim

To measure brain activity in near-death experiencers during a meditative state.

Methods

In two separate experiments, brain activity was measured with functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) during a Meditation condition and a Control condition. In the Meditation condition, participants were asked to mentally visualize and emotionally connect with the “being of light” allegedly encountered during their “near-death experience”. In the Control condition, participants were instructed to mentally visualize the light emitted by a lamp.

Results

In the fMRI experiment, significant loci of activation were found during the Meditation condition (compared to the Control condition) in the right brainstem, right lateral orbitofrontal cortex, right medial prefrontal cortex, right superior parietal lobule, left superior occipital gyrus, left anterior temporal pole, left inferior temporal gyrus, left anterior insula, left parahippocampal gyrus and left substantia nigra. In the EEG experiment, electrode sites showed greater theta power in the Meditation condition relative to the Control condition at FP1, F7, F3, T5, P3, O1, FP2, F4, F8, P4, Fz, Cz and Pz. In addition, higher alpha power was detected at FP1, F7, T3 and FP2, whereas higher gamma power was found at FP2, F7, T4 and T5.

Conclusions

The results indicate that the meditative state was associated with marked hemodynamic and neuroelectric changes in brain regions known to be involved either in positive emotions, visual mental imagery, attention or spiritual experiences.     

脑电图检查在重型颅脑损伤患者预后病情评估中的作用

目的 探讨脑电图检查在重型颅脑损伤患者预后病情评估中的作用.方法 选择57例重型颅脑损伤患者作为研究对象,对其临床资料进行回顾性分析.所有患者均行脑电图检查,对脑电图分级与格拉斯哥昏迷量表(GCS)评分、预后转归之间的关系进行分析.结果 57例重型颅脑损伤患者入院24h内脑电图检查全部异常.脑电图分级与GCS评分之间呈显著负相关(r=-0.742,P＜0.05):脑电图分级与预后转归之间呈显著正相关(r=0.730,P＜0.05).结论 脑电图检查及其分级可以评估重型颅脑损伤患者预后,为临床治疗提供参考依据.