Sensorimotor Recalibration Depends on Attribution of Sensory Prediction Errors to Internal Causes

Sensorimotor learning critically depends on error signals. Learning usually tries to minimise these error signals to guarantee optimal performance. Errors can, however, have both internal causes, resulting from one’s sensorimotor system, and external causes, resulting from external disturbances. Does learning take into account the perceived cause of error information? Here, we investigated the recalibration of internal predictions about the sensory consequences of one’s actions. Since these predictions underlie the distinction of self- and externally produced sensory events, we assumed them to be recalibrated only by prediction errors attributed to internal causes. When subjects were confronted with experimentally induced visual prediction errors about their pointing movements in virtual reality, they recalibrated the predicted visual consequences of their movements. Recalibration was not proportional to the externally generated prediction error, but correlated with the error component which subjects attributed to internal causes. We also revealed adaptation in subjects’ motor performance which reflected their recalibrated sensory predictions. Thus, causal attribution of error information is essential for sensorimotor learning.     

多普勒超声引导下行痔动脉结扎术术前肠道准备时机探讨

目的:探讨多普勒超声引导下行痔动脉结扎术(DG-HAL)患者口服复方聚乙二醇电解质行肠道准备的时机.方法:采取前瞻性随机对照的方法,从2010年7月到2011年6月,共有120例接受DG-HAL术的痔患者被随机分成对照组和护理干预组,各60例.对照组术前1天16:00口服复方聚乙二醇电解质,实验组手术当天4:30口服复方聚乙二醇电解质,比较两种方法服药后初次排便时间、自行排便次数、大量不保留灌肠次数;患者手术前晚的食欲、睡眠情况;肠道清洁程度.结果:两组服药后初次排便时间、自行排便次数、排清水样大便时间、大量不保留灌肠次数差异无统计学意义;患者手术前晚的食欲、睡眠情况和肠道清洁程度差异有统计学意义.结论:实验组术日晨口服复方聚乙二醇电解质用于DG-HAL术术前肠道准备,手术前晚食欲、睡眠情况及肠道清洁程度均优于对照组.     

A Supramodal Neural Network for Speech and Gesture Semantics: An fMRI Study

In a natural setting, speech is often accompanied by gestures. As language, speech-accompanying iconic gestures to some extent convey semantic information. However, if comprehension of the information contained in both the auditory and visual modality depends on same or different brain-networks is quite unknown. In this fMRI study, we aimed at identifying the cortical areas engaged in supramodal processing of semantic information. BOLD changes were recorded in 18 healthy right-handed male subjects watching video clips showing an actor who either performed speech (S, acoustic) or gestures (G, visual) in more (+) or less (−) meaningful varieties. In the experimental conditions familiar speech or isolated iconic gestures were presented; during the visual control condition the volunteers watched meaningless gestures (G−), while during the acoustic control condition a foreign language was presented (S−). The conjunction of the visual and acoustic semantic processing revealed activations extending from the left inferior frontal gyrus to the precentral gyrus, and included bilateral posterior temporal regions. We conclude that proclaiming this frontotemporal network the brain''s core language system is to take too narrow a view. Our results rather indicate that these regions constitute a supramodal semantic processing network.     

Beyond Motor Scheme: A Supramodal Distributed Representation in the Action-Observation Network

The representation of actions within the action-observation network is thought to rely on a distributed functional organization. Furthermore, recent findings indicate that the action-observation network encodes not merely the observed motor act, but rather a representation that is independent from a specific sensory modality or sensory experience. In the present study, we wished to determine to what extent this distributed and ‘more abstract’ representation of action is truly supramodal, i.e. shares a common coding across sensory modalities. To this aim, a pattern recognition approach was employed to analyze neural responses in sighted and congenitally blind subjects during visual and/or auditory presentation of hand-made actions. Multivoxel pattern analyses-based classifiers discriminated action from non-action stimuli across sensory conditions (visual and auditory) and experimental groups (blind and sighted). Moreover, these classifiers labeled as ‘action’ the pattern of neural responses evoked during actual motor execution. Interestingly, discriminative information for the action/non action classification was located in a bilateral, but left-prevalent, network that strongly overlaps with brain regions known to form the action-observation network and the human mirror system. The ability to identify action features with a multivoxel pattern analyses-based classifier in both sighted and blind individuals and independently from the sensory modality conveying the stimuli clearly supports the hypothesis of a supramodal, distributed functional representation of actions, mainly within the action-observation network.     

Selective Attention Modulates the Direction of Audio-Visual Temporal Recalibration

Temporal recalibration of cross-modal synchrony has been proposed as a mechanism to compensate for timing differences between sensory modalities. However, far from the rich complexity of everyday life sensory environments, most studies to date have examined recalibration on isolated cross-modal pairings. Here, we hypothesize that selective attention might provide an effective filter to help resolve which stimuli are selected when multiple events compete for recalibration. We addressed this question by testing audio-visual recalibration following an adaptation phase where two opposing audio-visual asynchronies were present. The direction of voluntary visual attention, and therefore to one of the two possible asynchronies (flash leading or flash lagging), was manipulated using colour as a selection criterion. We found a shift in the point of subjective audio-visual simultaneity as a function of whether the observer had focused attention to audio-then-flash or to flash-then-audio groupings during the adaptation phase. A baseline adaptation condition revealed that this effect of endogenous attention was only effective toward the lagging flash. This hints at the role of exogenous capture and/or additional endogenous effects producing an asymmetry toward the leading flash. We conclude that selective attention helps promote selected audio-visual pairings to be combined and subsequently adjusted in time but, stimulus organization exerts a strong impact on recalibration. We tentatively hypothesize that the resolution of recalibration in complex scenarios involves the orchestration of top-down selection mechanisms and stimulus-driven processes.     

Sensorimotor integration: locating locomotion in neural circuits

Neural components of the circuits that transform sensory cues into changes in motor activities are largely unknown. Several recent studies have now functionally mapped the sensorimotor circuits responsible for locomotion behaviors under defined environmental conditions in the nematode Caenorhabditis elegans.     

Sensorimotor gating: startle submits to presynaptic inhibition

Prepulse inhibition is a type of sensorimotor gating that is disrupted in some neuropsychiatric disorders. Its cellular basis has eluded investigators but now, using a molluscan model system, a cellular mechanism has been established.     

Supralinear and Supramodal Integration of Visual and Tactile Signals in Rats: Psychophysics and Neuronal Mechanisms

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Sensorimotor control of the spine.

The spinal viscoelastic structures including disk, capsule and ligaments were reviewed with special focus on their sensory motor functions. Afferent capable of monitoring proprioceptive and kinesthetic information are abundant in the disc, capsule and ligament. Electrical stimulation of the lumbar afferents in the discs, capsules and ligaments seem to elicit reflex contraction of the multifidus and also longissimus muscles. The muscular excitation is pronounced in the level of excitation and with weaker radiation 1 to 2 levels above and below. Similarly, mechanical stimulation of the spinal viscoelastic tissues excites the muscles with higher excitation intensity when more than one tissue (ligaments and discs for example) is stimulated. Overall, it seems that spinal structures are well suited to monitor sensory information as well as to control spinal muscles and probably also provide kinesthetic perception to the sensory cortex.     

Prominent Inhibitory Projections Guide Sensorimotor Computation: An Invertebrate Perspective

From single‐cell organisms to complex neural networks, all evolved to provide control solutions to generate context‐ and goal‐specific actions. Neural circuits performing sensorimotor computation to drive navigation employ inhibitory control as a gating mechanism as they hierarchically transform (multi)sensory information into motor actions. Here, the focus is on this literature to critically discuss the proposition that prominent inhibitory projections form sensorimotor circuits. After reviewing the neural circuits of navigation across various invertebrate species, it is argued that with increased neural circuit complexity and the emergence of parallel computations, inhibitory circuits acquire new functions. The contribution of inhibitory neurotransmission for navigation goes beyond shaping the communication that drives motor neurons, and instead includes encoding of emergent sensorimotor representations. A mechanistic understanding of the neural circuits performing sensorimotor computations in invertebrates will unravel the minimum circuit requirements driving adaptive navigation.     

Sensorimotor regulation of movements: Novel strategies for the recovery of mobility

A series of observations have provided important insight into properties of the spinal as well as supraspinal circuitries that control posture and movement. We have demonstrated that spinal rats can regain full weight-bearing standing and stepping over a range of speeds and directions with the aid of electrically enabling motor control (eEmc), pharmacological modulation (fEmc), and training [1, 2]. Also, we have reported that voluntary control movements of individual joints and limbs can be regained after complete paralysis in humans [3, 4]. However, the ability to generate significant levels of voluntary weight-bearing stepping with or without epidural spinal cord stimulation remains limited. Herein we introduce a novel method of painless transcutaneous electrical enabling motor control (pcEmc) and sensory enabling motor control (sEmc) strategy to neuromodulate the physiological state of the spinal cord. We have found that a combination of a novel non-invasive transcutaneous spinal cord stimulation and sensory-motor stimulation of leg mechanoreceptors can modulate the spinal locomotor circuitry to state that enables voluntary rhythmic locomotor movements.     

Self-Biting in Caged Macaques: Cause, Effect, and Treatment

Injurious self-biting is one of the most serious problems in primate colonies (Niemeyer, Gray, & Stephen, 1996). “Approximately 10% of captive, individually-housed monkeys engage in the disturbing phenomenon of self-injurious behavior (SIB). To date, no adequate explanation or effective therapy has been developed for this disorder ”(Jorgensen, Novak, Kinsey, Tiefenbacher, & Meyer, 1996; cf. Novak, Kinsey, Jorgensen, & Hazen, 1998). In rhesus macaques-the predominant species found in laboratories-the incidence of self-biting may be as high as 14% (recorded in a colony of 188 single-caged males; Jorgensen, Kinsey, & Novak, 1998). Individuals affected with this “behavioral pathology ”(Erwin & Deni, 1979, p. 4) repeatedly bite parts of their own bodies (see Figure 1) while intermittently showing signs of intense excitation such as threatening, trembling, head jerking, and piloerection (Reinhardt, 1999; Tinklepaugh, 1928).     

Self-Biting in Caged Macaques: Cause,Effect, and Treatment

Injurious self-biting is one of the most serious problems in primate colonies (Niemeyer, Gray, & Stephen, 1996). "Approximately 10% of captive, individually-housed monkeys engage in the disturbing phenomenon of self-injurious behavior (SIB). To date, no adequate explanation or effective therapy has been developed for this disorder" (Jorgensen, Novak, Kinsey, Tiefenbacher, & Meyer, 1996; cf. Novak, Kinsey, Jorgensen, & Hazen, 1998). In rhesus macaques-the predominant species found in laboratories-the incidence of self-biting may be as high as 14% (recorded in a colony of 188 single-caged males; Jorgensen, Kinsey, & Novak, 1998). Individuals affected with this "behavioral pathology" (Erwin & Deni, 1979, p. 4) repeatedly bite parts of their own bodies (see Figure 1) while intermittently showing signs of intense excitation such as threatening, trembling, head jerking, and piloerection (Reinhardt, 1999; Tinklepaugh, 1928).     

研究报告: 大鼠感觉运动系统静息态脑网络研究

为了理解啮齿类动物的脑功能连接,本文利用9.4T fMRI获得轻度麻醉状态下大鼠静息状态及刺激激活的数据,通过互相关分析构建节点之间的相关系数矩阵并计算相应的网络参数．结果发现：给予前爪电刺激时,刺激对侧初级感觉皮层(S1)、丘脑(Tha)有较强的正激活,双侧尾状壳核(CPu)有较强的负激活．静息状态时大鼠感觉/运动皮层内部、丘脑内部的连接性较强,而感觉/运动皮层与丘脑之间的连接较弱,双侧感觉运动系统之间存在较强的同步低频振荡,感觉运动系统在静息态时的脑网络具有小世界属性．结果提示,啮齿类动物在大脑信息处理中的功能分离和整合可能与人类存在某些相似性,支持哺乳动物中枢神经系统的基本功能存在遗传保守性的观点．