Spontaneous phasic activity in the brain: differences between waves in lateral geniculate and central lateral nuclei across sleep states

SUMMARY  Ponto-geniculo-occipital (PGO) waves are spontaneously-occurring macropotential waveforms recorded in the pons, lateral geniculate body (LGB) and occipital cortex. PGO waves mark the onset and course of rapid eye movement sleep (REM). PGO-like waves can be recorded in several brain areas including the thalamic central lateral nucleus (CL). Alerting stimuli elicit PGO waves (PGO_E) from LGB and waves from CL (CL_E) in all behavioural states. We compared spontaneous activity in LGB and CL across behavioral states to examine the relationship of CL waves to PGO waves. Spontaneous waves in LGB and CL may occur concurrently or separately in all states. Although REM is marked by a high level of LGB PGO activity, CL waves are rare. Frequencies of CL and LGB waves are similar in non-REM (NREM) although the waves do not necessarily occur at the same time. These findings suggest that the widespread phasic activity recorded throughout the brain in sleep cannot be assumed to be a non-specific unitary phenomenon propagated from a single brainstem generator.     

Effects of different speeds of induction with sevoflurane on the EEG in Man

The effects of two kinds of induction speed of sevoflurane anesthesia on the EEG pattern were compared in the same individual using medical student volunteers: a first exposure of 4% was given, followed after full recovery, by incremental doses of 1, 2 and 4% successively, each being administered for 10min. The arterial blood level of the anesthetic was measured using gaschromatograph. The changes of EEG pattern during fast induction with 4% were not represented by the abbreviation of those observed during the slow induction with the incremental doses. The administration of 4% induced a sudden appearance of high voltage, rhythmic slow waves of 2–3Hz at 1–3min when the arterial blood anesthetic level increased maximally, which was then followed by a pattern of faster activities of 10–14Hz mixed with 5–8Hz slow waves. In contrast, the administration of incremental doses induced an increase in frequency and amplitude of EEG activities in the light plane, followed by their decreases in deeper planes. The final EEG patterns were identical for both these methods of induction. These findings confirmed our previous hypothesis that not only the arterial blood level of anesthetics but the rate of its increase are important factors determining the EEG pattern of anesthesia.(Avramov MN et al.: Effects of different speeds of induction with sevoflurane on the EEG in man. J Anesth 1: 1–7, 1987)     

Are eye movement evoked potentials different from pattern reversal evoked potentials?

The averaged lambda wave elicited by saccadic eye movements across a checkerboard pattern has been reported to differ from checkerboard reversal evoked reponses, even when the electroencephalographic responses were corrected for the artefact caused by the movement of the dipole moment of the eye itself. Because of these differences it was suggested that the recording of the lambda wave might provide extra information in pathological circumstances. We performed experiments in which the parameters of the pattern (high contrast checkerboard pattern, 20 checks, large field 72 × 72 degrees) shift across the retina were carefully adjusted. For instance, eye movements were made across an integer and odd number of checks in order to mimic the pattern reversal. Furthermore, the timing of the pattern movement in the pattern reversal condition was adjusted so as to simulate the saccadic eye movement. The results seem to suggest that the reported dissimilarities between pattern reversal and eye movement evoked responses can be accounted for by the small differences of the retinal shift in the two conditions.     

松质骨中两种纵波的传播特性分析

基于松质骨的层状模型，利用Schoenberg理论分析了松质骨中两种纵波(快纵波和慢纵波)的传播特性；并在理论和实验上详细分析了骨小梁方向与传播方向间的夹角对松质骨中快纵波和慢纵波传播特性的影响。分析结果表明，当超声波平行于骨小梁入射时，松质骨中两种纵波都传播，入射角度在60度附近时，松质骨中两种纵波的相速度曲线有一个转折点，入射角度在60度以上，角度越大时，骨髓和骨小梁耦合得越紧，因此阻止了慢纵波的传播，而只有快纵波传播。     

Hypothesized neural dynamics of working memory: several chunks might be marked simultaneously by harmonic frequencies within an octave band of brain waves

The capacity of working memory (WM) for up to about seven simple items holds true both for humans and other species, and may depend upon a common characteristic of mammalian brains. This paper develops the conjecture that each WM item is represented by a different brain wave frequency. The binding-by-synchrony hypothesis, now being widely investigated, holds that the attributes of a single cognitive element cohere because electroencephalogram (EEG) synchrony temporarily unifies their substrates, which are distributed among different brain regions. However, thought requires keeping active more than one cognitive element, or WM "chunk," at a time. If there is indeed a brain wave frequency code for cognitive item-representations that are copresent within the same volume of neural tissue, the simple mathematical relationships of harmonies could provide a basis for maintaining distinctness and for orderly changes. Thus, a basic aspect of music may provide a model for an essential characteristic of WM. Music is a communicative phenomenon of "intermediate complexity," more highly organized than the firing patterns of individual neurons but simpler than language. If there is a distinct level of neural processing within which the microscopic physiological activity of neurons self-organizes into the macroscopic psychology of the organism, it might require such moderate complexity. Some of the obvious properties of music--orderly mixing and transitions among limited numbers of signal lines-are suggestive of properties that a dynamic neural process might need in order to organize and reorganize WM markers, but there are a number of additional, nonobvious advantageous properties of summating sinusoids in music-like relationships. In particular, harmonies register a stable periodic signal in the briefest possible time. Thus, the regularity of summating sinusoids whose frequencies bear harmony ratios suggests a particular kind of tradeoff between parallel and serial processing. When there are few copresent waves, at EEG frequencies, this sort of parallel coding retains behaviorally meaningful brief periods. A necessary companion hypothesis is that the brain wave frequencies underlying WM are confined to a single octave; that is, the upper and lower bounds of the band are in the ratio of 2:1. This hypothesized restriction, suggested by an empirical property of EEG bands that has been widely reported but rarely commented upon, has the important property of precluding spurious difference rhythms. A restriction to an octave, of "harmonious" frequency-markers for WM items, also seems consistent with a great deal of behavioral data suggesting that WM comprises a rapidly fading trace process in which only up to three or four item-representations are strongly activated simultaneously. There is also an additional, sequential renewal-or-revision process, within which up to another three or four items are being actively refreshed by rehearsal or replaced. Such serial processing may involve a less stringent octave band crowding problem.     

F波和面神经电图对早期周围性面瘫预后诊断的价值

目的 通过随访调查评价F波和面神经电图在早期周围性面瘫预后中的价值。方法 对发病21天内做过F波和面神经电图检查、病史已达3年的35例周围性面瘫患者进行了恢复结果随访,比较两种诊断方法预后判断的准确度。F波是否存在及面神经电图值是否大于90％分别作为两种方法的诊断界值。结果 用F波是否能引出判断周围性面瘫患者好坏的准确度为97.14％,高于面神经电图的88.57％,用F波是否消失判断患者有无并发症的准确度为94.29％,高于面神经电图的85.71％,两种方法经配对卡方检验,有显著性差异(x~2=17.72,P<0.01)。F波存在是较好预后的定性指标。结论 F波是早期周围性面瘫一种理想的判断预后的客观诊断指标。     

声测胆经体表循行线的实验研究

足少阳胆经，多弯多折，循行线长，检测难度较大。本文用低频输声的方法对３９名健康学生进行了右侧胆经的全程检测，循经性波出现率达到７２．７３％～９０．００％。再次证实了低频声波具有循本经经线传导的特异性，其传导轨迹与古典描述的胆经经线十分一致，并客观证实了胆经走行中５处弯曲的存在，同时也证实了胆经与三焦经、肝经的衔接，显示了经络是声的良导路     

周围性面瘫电生理检查与预后相关分析

目的 评价面神经电图（ENoG）、F波和瞬目反射（BR）等电生理检查在早期周围性面瘫预后判断中的价值及相关性.方法 对发病3周内行ENoG、F波和BR检测的31例周围性面瘫患者的恢复情况进行随访,时间6个月～2年,分别以F波、BR异常与否以及ENoG是否≥90％作为诊断界值,比较3种诊断方法判断预后的准确度以及三者间的相关性.结果 3种方法均能准确判断周围性面瘫的预后,ENoG≥ 90％、F波和BR异常均预示预后差.Pearson相关性分析显示,F波和BR结果之间（r=0.674,P＜0.01）、ENoG与BR间（r =0.445,P＜ 0.05）具有一定的相关性,ENoG与F波的无相关性（r=0.251,P＞0.05）.结论 结合多项适当的电生理检查全面综合分析,对周围性面瘫早期预后判断起重要作用.     

大脑功能及α波优势频分析在厌学青少年的应用

目的探讨厌学青少年大脑功能状态和α波优势频特点及对心理咨询的指导价值。方法以厌学进行心理咨询的青少年为研究组,以发展咨询的青少年为对照组。统一使用ML-2001脑功能状态检查仪对其脑功能状态和α波优势竞争频率及熵值进行测量,并对测量结果进行分析。结果两组的α波竞争优势主频分布于各频之间无显著性差异,但主频与次频之差均值和熵值差异显著（P〈0.01）;各脑区同时段主频不统一和多频互扰现象和大脑少氧、疲劳、左右对称性、前后功率逆转情况差异显著（P〈0.01）。结论厌学青少年大脑工作状态和脑电活动的有序性和统一性较差,影响厌学青少年的认知和行为。     

Four Waves of the COVID-19 Pandemic: Comparison of Clinical and Pregnancy Outcomes

During the last two and a half years, clinical manifestations, disease severity, and pregnancy outcomes have differed among pregnant patients with SARS-CoV-2 infection. These changes were preceded by the presence of new variants of SARS-CoV-2, known in the literature as variants of concern. The aim of this study is to describe the differences between maternal clinical characteristics and perinatal outcomes among pregnant women with COVID-19 during four waves of the COVID-19 epidemic in Serbia. This retrospective study included a series of 192 pregnant patients who were hospitalized due to the severity of their clinical status of SARS-CoV-2 infection. During four outbreaks of COVID-19 infection in Serbia, we compared and analyzed three sets of variables, including signs, symptoms, and characteristics of COVID-19 infection, clinical endpoints, and maternal and newborn parameters. During the dominance of the Delta variant, the duration of hospitalization was the longest (10.67 ± 1.42 days), the frequency of stillbirths was the highest (17.4%), as well as the frequency of progression of COVID infection (28.9%) and the requirement for non-invasive oxygen support (37%). The dominance of the Delta variant was associated with the highest number of prescribed antibiotics (2.35 ± 0.28), the most common presence of nosocomial infections (21.7%), and the highest frequency of corticosteroid therapy use (34.8%). The observed differences during the dominance of four variants of concern are potential pathways for risk stratification and the establishment of timely and proper treatments for pregnant patients. Early identification of the Delta variant, and possibly some new variants with similar features in the future, should be a priority and, perhaps, even an opportunity to introduce more accurate and predictive clinical algorithms for pregnant patients.