Brainstem control of sensory information: a mechanism for perception

We have proposed a theory in which pathways ascending from the brainstem reticular formation control sensory centers in the dorsal thalamus and neocortex. We assumed that the sensory messages received at a given level are transformed by a stochastic process, called Alopex, in a way which maximizes responses in central feature analyzers. Perception is seen as a process involving a close cyclic interaction between brainstem and sensory relays. We discuss the specific case of visual information flow and the proposed modification of visual images at the level of the dorsal lateral geniculate nucleus (dLGN). Computer simulations of a simple model, representing the dLGN and reafferent control emanating from the reticular formation, show that sensory features are effectively enhanced and--in the absence of sensory input--quasi-sensory features may be generated by feedback of a simple scalar variable that is formed by the non-linear superposition of the responses of any number of feature analyzers. The model proposes a specific mechanism for such processes as visual imagery, hallucinations, and dreaming, and provides a framework for further studies into the nature of cognitive brain functions.     

Setting out the frame conditions for feasible use of FFPE derived RNA

Introduction

The usage of formalin-fixed paraffin embedded (FFPE) tissue is characterized by its long shelf-life and simple handling. Therefore it is the most commonly available tissue specimen in routine diagnostics and histological studies. Formaldehyde fixation may result in RNA degradation and cross linking with proteins, while storage conditions also affect RNA integrity. The present study was designed to investigate the influence of these factors on RNA analysis.

How is electrical stimulation of the brain experienced,and how can we tell? Selected considerations on sensorimotor function and speech

ABSTRACT

Electrical stimulation of the nervous system is a powerful tool for localizing and examining the function of numerous brain regions. Delivered to certain regions of the cerebral cortex, electrical stimulation can evoke a variety of first-order effects, including observable movements or an urge to move, or somatosensory, visual, or auditory percepts. In still other regions the subject may be oblivious to the stimulation. Often overlooked, however, is whether the subject is aware of the stimulation, and if so, how the stimulation is experienced by the subject. In this review of how electrical stimulation has been used to study selected aspects of sensorimotor and language function, we raise questions that future studies might address concerning the subjects’ second-order experiences of intention and agency regarding evoked movements, of the naturalness of evoked sensory percepts, and of other qualia that might be evoked in the absence of an overt first-order experience.     

肺癌患者化疗前后血清Hcy、IGF-Ⅱ和TSGF检测的临床意义

目的：探讨肺癌患者化疗前后血清Hcy、IGF-Ⅱ和TSGF水平的变化及临床意义。方法：应用免疫法和放射免疫分析对35例肺癌患者进行了血清Hcy、IGF-Ⅱ和TSGF含量检测,并与30名正常健康人作比较。结果：肺癌患者在化疗前血清Hcy、IGF-Ⅱ和TSGF水平均非常显著地高于正常人组（P〈0.01）,化疗后6个月在未复发的27例中明显下降接近于正常人组,而复发的8例,其数值又回升至化疗前水平（P〈0.05）。结论：检测肺癌患者血清Hcy、IGF-Ⅱ和TSGF水平的变化可作为诊断和疗效观察的参考。     

艾滋病自愿咨询检测行为影响因素调查

目的了解大众艾滋病相关认知水平对于自愿咨询检测（VCT）的影响，为VCT的社区倡导提供依据。方法限定时段内对于自愿咨询检测门诊的求询者和整群抽取的社区居民进行包括人口学特征、艾滋病相关认知、VCT需求和行为的调查。采用描述性统计和Logistic回归对资料进行分析。结果VCT对传播途径的认知水平（Z=3．24314，P=0．0012）和公共卫生焦虑程度（Z=1．92708，P=0．0540）明显高于社区居民。对于存在感染风险者，主要影响其自愿咨询检测行为的是性别（OR=0．051，P=0．0001）、传播途径认知水平（OR=12．161，P=0．0264）、应对病毒的自我效能感（OR=3，252，P=0．0343）和流行现状焦虑（OR=1．576，P=0．0305）等。结论人口学特征对于合理检测行为的影响并非关键，在VCT社区倡导中要加强流行状况的介绍提高防治紧迫感，详细解释传播风险以提高风险自觉性，同时通过介绍HIV的防治方法以提高应对病毒的自我效能感也有助于促进自愿咨询检测。     

用于选择视觉的数据和智能控制神经网络系统(英文)

在这篇论文中,我们提出了用于选择视觉的数据和智能控制的动态网络系统的神经实现过程。模型由数个相互作用的子系统构成,用于不同的处理。所有的神经子系统与信息和控制流程的倒序和顺序紧密相关。     

妊高征患者治疗前后血清TNF-α、IL-6和IL-8检测的临床意义

目的：探讨了妊高征患者治疗前后血清TNF-α、IL-6和IL-8水平的变化及意义。方法：采用放射免疫分析对36例妊高征患者进行了血清TNF-α、IL-6和IL-8水平检测并与35名正常孕妇作比较。结果：在治疗前血清TNF-α、IL-6和IL-8水平非常显著地高于正常孕妇组（P〈0．01），经治疗后2周，血清TNF-α、IL-6和IL-8水平与正常孕妇组比较，无显著性差异（P〉0．05）。结论：炎性细胞因子TNF-α、IL-6和IL-8在妊高征的发病机理中具有重要的作用，有一定的临床价值。     

The Topography of Non-Linear Cortical Dynamics at Rest, in Mental Calculation and Moving Shape Perception

Differential cortical activation by cognitive processing was studied using dimensional complexity, a measure derived from nonlinear dynamics that indicates the degrees of freedom (complexity) of a dynamic system. We examined the EEG of 32 healthy subjects at rest, during a visually presented calculation task, and during a moving shape perception task. As a nonlinear measure of connectivity, the mutual dimension of selected electrode pairs was used. The first Lyapunov coefficient was also calculated. Data were tested for non-linearity using a surrogate data method and compared to spectral EEG measures (power, coherence). Surrogate data testing confirmed the presence of nonlinear structure in the data. Cognitive activation led to a highly significant rise in dimensional complexity. While both tasks activated central, parietal and temporal areas, mental arithmetic showed frontal activation and an activity maximum at T3, while the moving shape task led to occipital activation and a right parietal activity maximum. Analysis of mutual dimension showed activation of a bilateral temporal-right frontal network in calculation. The Lyapunov coefficent showed clear topographic variation, but was not significantly changed by mental tasks (p<.09). While dimensional complexity was almost unrelated to power values, nonlinear (mutual dimension) and linear (coherence) measures of connectivity shared up to 37% of variance. Data are interpreted in terms of increased cortical complexity as a result of recruitment of asynchronously active, distributed neuronal assemblies in cognition. The topography of nonlinear dynamics are related to neuropsychological and neuroimaging findings on mental calculation and moving shape perception.     

Multisensory integration mechanisms in haptic space perception

It has been argued that representations of peripersonal space based on haptic input are systematically distorted by egocentric reference frames. Interestingly, a recent study has shown that noninformative vision (i.e., freely viewing the region above the haptic workspace) improves performance on the so-called haptic parallel-setting task, in which participants are instructed to rotate a test bar until it is parallel to a reference bar. In the present study, we made a start at identifying the different sensory integration mechanisms involved in haptic space perception by distinguishing the possible effects of orienting mechanisms from those of noninformative vision. We found that both the orienting direction of head and eyes and the availability of noninformative vision affect parallel-setting performance and that they do so independently: orienting towards a reference bar facilitated the parallel-setting of a test bar in both no-vision and noninformative vision conditions, and noninformative vision improved performance irrespective of orienting direction. These results suggest the effects of orienting and noninformative vision on haptic space perception to depend on distinct neurocognitive mechanisms, likely to be expressed in different modulations of neural activation in the multimodal parietofrontal network, thought to be concerned with multimodal representations of peripersonal space.     

Influence of interaction force levels on degree of motor adaptation in a stable dynamic force field

Studies have shown that the point-to-point reaching movements of subjects seated in a dark, rotating room demonstrate errors in movement trajectories and endpoints, consistent with the direction of the Coriolis force perturbations created by room rotation. Adaptation of successive reaches and the presence of postrotation aftereffects have indicated that subjects form internal models of the Coriolis field dynamics in order to make appropriate movement corrections. It has been argued that these findings are inconsistent with predictions of peripheral stabilization assumed in equilibrium-point models of motor control. A possibility that has been raised, however, is that the Coriolis field findings may in fact stem from changes in control commands elicited due to the magnitude and destabilizing nature of the Coriolis perturbations. That is, it has been suggested that a perturbation threshold exists, below which central reactions are not necessary in order to maintain movement stability. We tested the existence of a perturbation threshold in normal-speed reaching movements. Twelve normal human subjects performed non-visually guided reaching movements while grasping a robotic manipulandum. The endpoints and trajectory deviations of their movements were measured before, during, and after a position-dependent force field (similar to a Coriolis field in terms of the time history of applied forces) was applied to their movements. We examined the responses to a range of perturbation field strengths from small to considerable. Our experimental results demonstrated a substantial adaptation response over the entire range of perturbation field magnitudes examined. Neither the amount of adaptation after 5 trials nor after 25 trials was found to change as disturbance magnitudes decreased. These findings indicate that there is an adaptive response even for small perturbations; i.e., threshold behavior was not found. This result contradicts the assertion that peripheral stabilization mechanisms enable the central controller to ignore small details of peripheral or environmental dynamics. Our findings instead point to a central dynamic modeler that is both highly sensitive and continually active. The results of our study also showed that subjects were able to maintain baseline pointing accuracies despite exposure to perturbation forces of sizeable magnitude (more than 7 N).