The time course of implicit affective picture processing: an eye movement study

Consistent with a negativity bias account, neuroscientific and behavioral evidence demonstrates modulation of even early sensory processes by unpleasant, potentially threat-relevant information. The aim of this research is to assess the extent to which pleasant and unpleasant visual stimuli presented extrafoveally capture attention and impact eye movement control. We report an experiment examining deviations in saccade metrics in the presence of emotional image distractors that are close to a nonemotional target. We additionally manipulate the saccade latency to test when the emotional distractor has its biggest impact on oculomotor control. The results demonstrate that saccade landing position was pulled toward unpleasant distractors, and that this pull was due to the quick saccade responses. Overall, these findings support a negativity bias account of early attentional control and call for the need to consider the time course of motivated attention when affect is implicit

Exploration of the neural correlates of cerebral palsy for sensorimotor BCI control

Cerebral palsy (CP) includes a broad range of disorders, which can result in impairment of posture and movement control. Brain-computer interfaces (BCIs) have been proposed as assistive devices for individuals with CP. Better understanding of the neural processing underlying motor control in affected individuals could lead to more targeted BCI rehabilitation and treatment options. We have explored well-known neural correlates of movement, including event-related desynchronization (ERD), phase synchrony, and a recently-introduced measure of phase dynamics, in participants with CP and healthy control participants. Although present, significantly less ERD and phase locking were found in the group with CP. Additionally, inter-group differences in phase dynamics were also significant. Taken together these findings suggest that users with CP exhibit lower levels of motor cortex activation during motor imagery, as reflected in lower levels of ongoing mu suppression and less functional connectivity. These differences indicate that development of BCIs for individuals with CP may pose additional challenges beyond those faced in providing BCIs to healthy individuals.

Gaze pursuit and arm control of adolescent males diagnosed with attention deficit hyperactivity disorder (ADHD) and normal controls: evidence of a dissociation in processing visual information of short and long duration

Three-dimensional kinematic analysis of line of gaze, arm and ball was used to describe the visual and motor behaviour of male adolescents diagnosed with attention deficit hyperactivity disorder (ADHD). The ADHD participants were tested when both on (ADHD-On) and off (ADHD-Off) their medication and compared to age-matched normal controls in a modified table tennis task that required tracking the ball and hitting to cued right and left targets. Long-duration information was provided by a pre-cue, in which the target was illuminated approximately 2 s before the serve, and short-duration information by an early-cue illuminated about 350 ms after the serve, leaving -500 ms to select the target and perform the action. The ADHD groups differed significantly from the control group in both the pre-cue and early-cue conditions in being less accurate, in having a later onset and duration of pursuit tracking, and a higher frequency of gaze on and off the ball. The use of medication significantly reduced the gaze frequency of the ADHD participants, but surprisingly this did not lead to an increase in pursuit tracking, suggesting a barrier was reached beyond which ball flight information could not be processed. The control and ADHD groups did not differ in arm movement onset, duration and velocity in the short-duration early-cue condition; in the long-duration pre-cue condition, however, the ADHD group's movement time onset and arm velocity differed significantly from controls. The results show that the ADHD groups were able to process short-duration information without experiencing adverse effects on their motor behaviour; however, long-duration information contributed to irregular movement control.

Continuous torque system with control of the reaction unit

This article describes an orthodontic system used to obtain active continuous torque with movement control of both active and reactive units; the system relies on principles of the segmented technique. A cantilever system with .017 x .025-in beta-titanium alloy wire was designed to provide the desirable moment on the active unit. A transpalatal bar or a lingual arch increases the anchorage and neutralizes the side effects on the reactive unit. This technique is an efficient approach for major corrections of buccolingual inclinations of certain teeth. © 2010 American Association of Orthodontists.

Investigation of the effect of movement and irrigation systems on temperature in the conventional drilling of cortical bone

We have compared the results of the external irrigation technique with those of a double irrigation technique with continuous intermittent movement. Maximum thermal measurements were made in the cortical part of 10 samples of bovine ribs during osteotomy to simulate the preparation of a surgical bed for the installation of dental implants at a depth of 10 mm Twenty specimens were drilled for each group: external irrigation and continuous movement (control group 1, CG1); external irrigation and intermittent movement (control group 2, CG2); double irrigation and continuous movement (test group 1, TG1); and double irrigation and intermittent movement (test group 2, TG2). The double irrigation technique gave significantly better results regardless of the drilling movement used. Thermal increases between samples was 19.2% in group CG1, 10.4% in CG2, 5.4% in TG1, and 3.4% in TG2. The double irrigation technique produced a significantly smaller increase in temperature in the cortical bone during both types of drilling (p = 0.001), which illustrated its greater efficiency compared with that of the external irrigation technique. (C) 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Verbal instructions and top-down saccade control.

Few studies have addressed the interaction between instruction content and saccadic eye movement control. To assess the impact of instructions on top-down control, we instructed 20 healthy volunteers to deliberately delay saccade triggering, to make inaccurate saccades or to redirect saccades--i.e. to glimpse towards and then immediately opposite to the target. Regular pro- and antisaccade tasks were used for comparison. Bottom-up visual input remained unchanged and was a gap paradigm for all instructions. In the inaccuracy and delay tasks, both latencies and accuracies were detrimentally impaired by either type of instruction and the variability of latency and accuracy was increased. The intersaccadic interval (ISI) required to correct erroneous antisaccades was shorter than the ISI for instructed direction changes in the redirection task. The word-by-word instruction content interferes with top-down saccade control. Top-down control is a time consuming process, which may override bottom-up processing only during a limited time period. It is questionable whether parallel processing is possible in top-down control, since the long ISI for instructed direction changes suggests sequential planning.

Disorganization and timing of motor behavior : insight from gesture impairments and movement patterns in schizophrenia

Background: Motor symptoms are frequent phenomena across the entire course of schizophrenia1. Some have argued that disorganized behavior was associated with aberrant motor behavior. We have studied the association of motor disturbances and disorganization in two projects focusing on the timing of movements. Method: In two studies, we assessed motor behavior and psychopathology. The first study applied a validated test of upper limb apraxia in 30 schizophrenia patients2,3. We used standardized video assessments of hand gestures by a blinded rater. The second study tested the stability of movement patterns using time series analysis in actigraphy data of 100 schizophrenia patients4. Both stability of movement patterns and the overall amount of movement were calculated from data of two hours with high degrees of social interaction comparable across the 100 subjects. Results: In total, 67% of the patients had gesture performance deficits3. Most frequently, they made spatial, temporal and body-part-as-object errors. Gesture performance relied on frontal lobe function2. Poor gesture performance was associated with increased disorganization scores. In the second study, we found disorganization to be predicted only by more irregular movement patterns irrespective of the overall amount of movement4. Conclusion : Both studies provide evidence for a link between aberrant timing of motor behavior and disorganization. Disturbed movement control seems critical for disorganized behavior in schizophrenia.

Development of a magnetic resonance compatible wrist device for the analysis of movement encoding in the brain

Tese de mestrado integrado em Engenharia Biomédica e Biofísica, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016

The relationship of cervical joint position error to balance and eye movement disturbances in persistent whiplash

Cervical joint position error (JPE) has been used as a measure of cervical afferent input to detect disturbances in sensori-motor control as a possible contributor to a neck pain syndrome. This study aimed to investigate the relationship between cervical JPE, balance and eye movement control. It was of particular interest whether assessment of cervical ME alone was sufficient to signal the presence of disturbances in the two other tests. One hundred subjects with persistent whiplash-associated disorders (WADs) and 40 healthy controls subjects were assessed on measures of cervical JPE, standing balance and the smooth pursuit neck torsion test (SPNT). The results indicated that over all subjects, significant but weak-to-moderate correlations existed between all comfortable stance balance tests and both the SPNT and rotation cervical ME tests. A weak correlation was found between the SPNT and right rotation cervical JPE. An abnormal rotation cervical JPE score had a high positive prediction value (88%) but low sensitivity (60%) and specificity (54%) to determine abnormality in balance and or SPNT test. The results suggest that in patients with persistent WAD, it is not sufficient to measure ME alone. All three measures are required to identify disturbances in the postural control system. (C) 2005 Elsevier Ltd. All rights reserved.

Control of mobile robotic platforms by handheld devices

The intent of this work was to develop a mobile robotic platform that was controlled by a Palm Pilot PDA. Advances in consumer electronics are producing powerful yet small handheld devices. Some of these devices present quasi-PC capabilities for a fraction of the cost; furthermore, they are compact enough that they fit in all but the smallest of platforms. The platform prototype built for testing purposes has a differential-drive configuration to provide simple but agile movement control. The sensor package consisted of two infrared ranging sensors mounted on servomotors that provide a wide area of detection. Building such a platform involved selection of hardware, circuit integration and software development. The software suite selected to develop code for the Palm Pilot was CodeWarrior, a C compiler that can generate code in Palm-native PRC files.

Force controlled hexapod walking

In this paper we describe the dynamic simulation of an 18 degrees of freedom hexapod robot with the objective of developing control algorithms for smooth, efficient and robust walking in irregular terrain. This is to be achieved by using force sensors in addition to the conventional joint angle sensors as proprioceptors. The reaction forces on the feet of the robot provide the necessary information on the robots interaction with the terrain. As a first step we validate the simulator by implementing movement control by joint torques using PID controllers. As an unexpected by-product we find that it is simple to achieve robust walking behaviour on even terrain for a hexapod with the help of PID controllers and by specifying a trajectory of only a few joint configurations.

Significant features of the epidemiology of equine influenza in Queensland, Australia, 2007.

An outbreak of equine influenza (EI) caused by influenza A H3N8 subtype virus occurred in the Australian states of Queensland and New South Wales in August 2007. Infection in the Australian horse population was associated with the introduction of infection by horses from overseas. The first case of EI in Queensland was detected on 25 August 2007 at an equestrian sporting event. Infection subsequently spread locally and to other clusters through horse movements prior to the implementation of an official standstill. There were five main clusters of infected properties during this outbreak and several outliers, which were investigated to find the potential mechanism of disease spread. To contain the outbreak, Queensland was divided into infection status zones, with different movement controls applied to each zone. Vaccination was implemented strategically in infected areas and within horse subpopulations. Control and eventual eradication of EI from Queensland was achieved through a combination of quarantine, biosecurity measures, movement control, rapid diagnostic testing and vaccination.

The oculomotor system: (1) Vertical-horizontal interaction and signal recognition, (2) Time delays and power spectra

In the first section of this thesis, two-dimensional properties of the human eye movement control system were studied. The vertical - horizontal interaction was investigated by using a two-dimensional target motion consisting of a sinusoid in one of the directions vertical or horizontal, and low-pass filtered Gaussian random motion of variable bandwidth (and hence information content) in the orthogonal direction. It was found that the random motion reduced the efficiency of the sinusoidal tracking. However, the sinusoidal tracking was only slightly dependent on the bandwidth of the random motion. Thus the system should be thought of as consisting of two independent channels with a small amount of mutual cross-talk.

These target motions were then rotated to discover whether or not the system is capable of recognizing the two-component nature of the target motion. That is, the sinusoid was presented along an oblique line (neither vertical nor horizontal) with the random motion orthogonal to it. The system did not simply track the vertical and horizontal components of motion, but rotated its frame of reference so that its two tracking channels coincided with the directions of the two target motion components. This recognition occurred even when the two orthogonal motions were both random, but with different bandwidths.

In the second section, time delays, prediction and power spectra were examined. Time delays were calculated in response to various periodic signals, various bandwidths of narrow-band Gaussian random motions and sinusoids. It was demonstrated that prediction occurred only when the target motion was periodic, and only if the harmonic content was such that the signal was sufficiently narrow-band. It appears as if general periodic motions are split into predictive and non-predictive components.

For unpredictable motions, the relationship between the time delay and the average speed of the retinal image was linear. Based on this I proposed a model explaining the time delays for both random and periodic motions. My experiments did not prove that the system is sampled data, or that it is continuous. However, the model can be interpreted as representative of a sample data system whose sample interval is a function of the target motion.

It was shown that increasing the bandwidth of the low-pass filtered Gaussian random motion resulted in an increase of the eye movement bandwidth. Some properties of the eyeball-muscle dynamics and the extraocular muscle "active state tension" were derived.

基于网络直角坐标机器人视觉伺服系统研究

为了实现定位抓取任务,提出基于网络的直角坐标机器人视觉控制系统。针对机器人运动控制的非线性与强耦合特性,采用神经网络控制器,构建了图像偏差与运动控制量之间的对应关系。通过对图像增强、边缘提取、特征提取等图像处理方法的综合分析,提出了一套优化组合图像处理法。在计算机网络环境下,采用自定义协议实现图像处理器与运动控制器协调控制,并将远程监控应用到机器人控制中。实验结果表明,该系统能够在视野范围内自动实现定位抓取动作。

化学冷铁——焓变涂料的研究

焓变涂料是以在一定的温度区间内可发生吸热化学反应的物质为基料配制的,将其涂在砂型(芯)表面,可代替常规冷铁.它对解决难于放置冷铁的串皮芯部位的激冷问题,效果明显.焓变涂料激冷作用的大小,取决于基料物质比焓变的大小以及涂层厚度等因素。