Perception-related modulations of local field potential power and coherence in primary visual cortex of awake monkey during binocular rivalry

Cortical synchronization at gamma-frequencies (35-90 Hz) has been proposed to define the connectedness among the local parts of a perceived visual object. This hypothesis is still under debate. We tested it under conditions of binocular rivalry (BR), where a monkey perceived alternations among conflicting gratings presented singly to each eye at orthogonal orientations. We made multi-channel microelectrode recordings of multi-unit activity (MUA) and local field potentials (LFP) from striate cortex (V1) during BR while the monkey indicated his perception by pushing a lever. We analyzed spectral power and coherence of MUA and LFP over 4-90 Hz. As in previous work, coherence of gamma-signals in most pairs of recording locations strongly depended on grating orientation when stimuli were presented congruently in both eyes. With incongruent (rivalrous) stimulation LFP power was often consistently modulated in consonance with the perceptual state. This was not visible in MUA. These perception-related modulations of LFP occurred at low and medium frequencies (< 30 Hz), but not at gamma-frequencies. Perception-related modulations of LFP coherence were also restricted to the low-medium range. In conclusion, our results do not support the expectation that gamma-synchronization in V1 is related to the perceptual state during BR, but instead suggest a perception-related role of synchrony at low and medium frequencies.     

Stimulus duration in working memory is represented by neuronal activity in the monkey prefrontal cortex

Humans are capable of memorizing several attributes of a presented stimulus as well as its duration of presentation. However, the neuronal representation of stimulus duration in memory remains unknown. This study investigated activities of single neurons in the prefrontal cortex of monkeys while they were performing a behavioral task in which working memory for stimulus duration was needed. Here we describe specific neurons whose discharge rates reflect encoding or retention of the duration of the presentation of stimuli to be remembered. We also describe other specific neurons whose activities reflect encoding or retention of fixed duration, similar but unrelated to the stimulus duration presented in each trial. Some of these specific neurons showed the same duration-related discharges even while the monkeys were performing a different task, in which working memory for stimulus duration was no longer needed. From these results, we suggest that neurons in the prefrontal cortex play roles in encoding and retention of temporal information in working memory and that some of those neurons are dedicated to representation of temporal information attributed to stimuli even when the temporal information is unnecessary for correct performance.     

How many positions can we perceptually encode,one or many?

Here we show that our sensitivity for discriminating relative position across the visual field is limited. In experiment 1 we show that we are much worse at detecting a texture defined by the relative position of elements within an array than would be expected if we had access to multiple estimates of relative position across the visual field. In experiment 2 we show that human performance is impaired for positional judgments when there is uncertainty as to which of a number of possible elements is misaligned. This impairment is greater than one would expect from an ideal observer model and greater than that found for a comparable task involving orientation. It is consistent with positional thresholds being determined by only one estimate of relative position. In experiment 3 we estimate the number of suprathreshold positional signals that can be pooled at the same time across the visual field using a standard summation variance paradigm. The results suggest that the human visual system is limited to one estimate of position, but additional estimates can be built up serially over time; however, this process is slow and probably cognitive in nature. These experiments taken as a whole suggest that only one estimate of relative position (i.e. relative to a predefined reference) at a time is accessible at the perceptual level.     

A single nucleotide polymorphism in the transmembrane domain coding region of HER-2 is associated with development and malignant phenotype of gastric cancer

Alterations of the HER-2 (erbB-2/neu) proto-oncogene have been associated with carcinogenesis and poor prognosis of certain cancers. A single nucleotide polymorphism (Ile/Val, A/G) in the transmembrane domain was reported to be associated with a risk of breast cancer. In our study, we examined the association between the HER-2 polymorphism and gastric carcinoma. The Ile/Ile, Ile/Val and Val/Val genotypes were found in 146 (68.9%), 56 (26.4%) and 10 (4.7%) of 212 gastric cancer patients and in 234 (81.5%), 48 (16.7%) and 5 (1.8%) of 287 control subjects, respectively. The Ile/Val or Val/Val genotype was significantly more frequent in patients than in controls (p = 0.005 and 0.033, respectively). The OR of Val/Val genotype then revealed a significantly enhanced risk of 3.25 (95% CI 1.09-9.70) compared to Ile/Ile genotype; heterozygous Ile/Val genotype showed an intermediate risk of 1.97 (1.27-3.06). In patients, carcinomas of advanced stage were significantly more frequent in patients with Ile/Val or Val/Val genotype than those with Ile/Ile genotype (p < 0.001). The logistic regression analysis for tumor invasion, lymph node metastasis and distant metastasis revealed that lymph node metastasis was most closely associated with the HER-2 genotype. These results suggest that this nucleotide polymorphism in the transmembrane domain-coding region of HER-2 could be associated with development of gastric carcinoma and may serve as a predictor of risk for a malignant phenotype of gastric cancer. The association of HER-2 genotype with clinicopathologic characteristics of gastric cancer was also suggested, which has to be confirmed with a larger sample size.     

Endocytosis and spatial restriction of cell signaling

Endocytosis and recycling are essential components of the wiring enabling cells to perceive extracellular signals and transduce them in a temporally and spatially controlled fashion, directly influencing not only the duration and intensity of the signaling output, but also their correct location. Here, we will discuss key experimental evidence that support how different internalization routes, the generation of diverse endomembrane platforms, and cycles of internalization and recycling ensure polarized compartmentalization of signals, regulating a number of physiological and pathologically-relevant processes in which the resolution of spatial information is vital for their execution.     

Optic tectum of the eastern garter snake, Thamnophis sirtalis. V. Morphology of brainstem afferents and general discussion

Brainstem neurons that project to the optic tectum of the eastern garter snake were identified by retrograde transport of horseradish peroxidase. The distribution and morphology of tectal afferent axons from the thalamus, pretectum, nucleus isthmi, and midbrain reticular formation were then studied by anterograde transport of horseradish peroxidase. Diencephalic projections to the tectum arise from the ventral lateral geniculate complex ipsilaterally and the ventrolateral nucleus, suprapeduncular nucleus, and nucleus of the ventral supraoptic decussation bilaterally. Three pretectal groups (the lentiform thalamic nucleus, the lentiform mesencephalic-pretectal complex and the geniculate pretectal nucleus) give rise to heavy, bilateral tectal projections. Small neurons in nucleus isthmi and large reticular neurons in nucleus lateralis profundus mesencephali also give rise to bilateral projections. Caudal to the tectum, projections arise bilaterally from the pontine and medullary tegmentum, nuclei of the lateral lemniscus, the posterior colliculus, and the sensory trigeminal nucleus. A small contralateral projection arises from the medial vestibular complex. Tectal afferents from the thalamus, pretectum, nucleus isthmi, and midbrain reticular formation had characteristic morphologies and laminar distributions within the tectum. However, these afferents fall into two groups based on their spatial organization. Afferents from the thalamus and nucleus isthmi arise from small neurons with spatially restricted, highly branched dendritic trees. Their axons terminate in single, highly branched and bouton-rich arbors about 100 micron in diameter. By contrast, afferents from the midbrain reticular formation and the pretectum arise from large neurons with long, radiate, and sparsely branched dendritic trees. Their axons course parallel to the tectal surface and emit numerous collateral branches that are distributed widely through the mediolateral and rostrocaudal extent of either the central or superficial gray layers. Each collateral bears several small, spatially disjunct clusters of boutons.     

利用网络资源查找疑难编码的疾病诊断

针对一些病案首页医师书写的疾病诊断在ICD-10第三卷书中无法直接查到，致使对其分类编码困难，诊断书写不规范及某些编码疑难的诊断是编码困难的主要原因，互联网为我们提供了丰富资源，编码人员需要学会利用互联网这一知识宝库的资源，查找网络相关内容获得“编码疑难的诊断”ICD-10编码。     

Prognosis of subacute low back pain patients according to pain response

Centralization of referred pain or failure to centralize has in earlier studies been shown to be a predictor of low back pain prognosis. Research suggests that there are differences in how males and females experience pain. The aim of this study was to evaluate the outcome after 1 year, and to evaluate the prognostic value of the pain response in a mechanical test at the first consultation at a spine clinic, and the influence of gender, in order to identify patients with especially high risk of chronicity. The patients in this study were low back pain patients, included consecutively from a spine clinic in Northern Denmark. The criteria for entering this spine clinic were neck or low back pain with radiating symptoms and a duration of 4–26 weeks, without satisfactory improvement after treatment in the primary care system. The 793 patients were categorised into four subgroups according to their pain response in a mechanical test performed at the initial examination: centralization, non-lasting centralization, peripheralization and no effect. The patients were instructed in doing specific exercises according to the test results. The four subgroups were compared after 1 year with regard to changes in back and leg pain, disability and return-to-work status. The statistical evaluation was undertaken for the study group as a whole and stratified according to gender. A significant improvement in all outcome measures was found in all the subgroups, among both men and women. There were no systematic or statistically significant differences in the prognosis between the four subgroups of patients. The proportion of Centralizers in this study was 18%. The mechanical test at baseline is important for deciding the subject-specific exercises, but when treated according to test results, the prognostic value of the test seems limited. The project is approved by the Regional Scientific Ethical Committee.     

γ-氨基丁酸能受体在嗅觉编码中作用的仿真研究

目的在建立蝗虫触角叶仿真模型的基础上，通过改变γ-氨基丁酸能（GABA，抑制性神经递质）突触电流的仿真参数．研究抑制性连接对嗅觉时空编码的影响。方法利用Hodgkin—Huxley方程，建立离子电流模型的常微分方程，运用MATLAB软件进行求解，计算每个兴奋性神经元（PN）动作电位相对于局部场电位峰值的相位，重复仿真计算20次。显示结果用黑点表示。结果阻断GABA突触连接会影响PNs的响应模式，具体表现在与局部场电压（LFP）保持同步的PNs的个数将会发生变化。结论进一步认识同步振荡现象和突触连接在嗅觉识别中起的关键作用。