Early Video-assisted Thoracoscopic Surgery or Intrapleural Enzyme Therapy in Pleural Infection: A Feasibility Randomized Controlled Trial. The Third Multicenter Intrapleural Sepsis Trial-MIST-3.

Assessing the early use of video-assisted thoracoscopic surgery (VATS) or intrapleural enzyme therapy (IET) in pleural infection requires a phase III randomized controlled trial (RCT). To establish the feasibility of randomization in a surgery-versus-nonsurgery trial as well as the key outcome measures that are important to identify relevant patient-centered outcomes in a subsequent RCT. The MIST-3 (third Multicenter Intrapleural Sepsis Trial) was a prospective multicenter RCT involving eight U.

Clinical application of eye movement tasks as an aid to understanding Parkinson's disease pathophysiology.

Parkinson's disease (PD) is a progressive neurodegenerative disorder of the basal ganglia. Most PD patients suffer from somatomotor and oculomotor disorders. The oculomotor system facilitates obtaining accurate information from the visual world.

Impaired smooth-pursuit in Parkinson's disease: normal cue-information memory, but dysfunction of extra-retinal mechanisms for pursuit preparation and execution.

While retinal image motion is the primary input for smooth-pursuit, its efficiency depends on cognitive processes including prediction. Reports are conflicting on impaired prediction during pursuit in Parkinson's disease. By separating two major components of prediction (image motion direction memory and movement preparation) using a memory-based pursuit task, and by comparing tracking eye movements with those during a simple ramp-pursuit task that did not require visual memory, we examined smooth-pursuit in 25 patients with Parkinson's disease and compared the results with 14 age-matched controls.

Influence of predictability on control of extra-retinal components of smooth pursuit during prolonged 2D tracking.

We compared pursuit responses to 2D target motion in three separate conditions: predictable, randomised and randomised with timing cues. The target moved on a continuous quadrilateral path in which right-angle direction changes allowed anticipatory eye acceleration and deceleration in orthogonal axes to be assessed. Results indicated that whether the timing of direction changes was random or predictable, anticipatory acceleration, initiated by extra-retinal mechanisms, occurred in the new direction at approximately the same time as anticipatory deceleration in the terminating direction, but deceleration was of greater magnitude than acceleration.

Normal aging affects movement execution but not visual motion working memory and decision-making delay during cue-dependent memory-based smooth-pursuit.

Aging affects virtually all functions including sensory/motor and cognitive activities. While retinal image motion is the primary input for smooth-pursuit, its efficiency/accuracy depends on cognitive processes. Elderly subjects exhibit gain decrease during initial and steady-state pursuit, but reports on latencies are conflicting.

In pursuit of delay-related brain activity for anticipatory eye movements.

How the brain stores motion information and subsequently uses it to follow a moving target is largely unknown. This is mainly due to previous fMRI studies using paradigms in which the eye movements cannot be segregated from the storage of this motion information. To avoid this problem we used a novel paradigm designed in our lab in which we interlaced a delay (2, 4 or 6 seconds) between the 1(st) and 2(nd) presentation of a moving stimulus.

Cue-dependent memory-based smooth-pursuit in normal human subjects: importance of extra-retinal mechanisms for initial pursuit.

Using a cue-dependent memory-based smooth-pursuit task previously applied to monkeys, we examined the effects of visual motion-memory on smooth-pursuit eye movements in normal human subjects and compared the results with those of the trained monkeys. These results were also compared with those during simple ramp-pursuit that did not require visual motion-memory. During memory-based pursuit, all subjects exhibited virtually no errors in either pursuit-direction or go/no-go selection.

Cognitive processes involved in smooth pursuit eye movements: behavioral evidence, neural substrate and clinical correlation.

Smooth-pursuit eye movements allow primates to track moving objects. Efficient pursuit requires appropriate target selection and predictive compensation for inherent processing delays. Prediction depends on expectation of future object motion, storage of motion information and use of extra-retinal mechanisms in addition to visual feedback.

Facilitation of ocular pursuit during transient occlusion of externally-generated target motion by concurrent upper limb movement.

Smooth pursuit during prolonged occlusion is improved in the presence of sensorimotor signals when tracking self-generated target motion. The current study investigated whether concurrent arm tracking of externally-generated target motion conveys a similar facilitation to ocular pursuit of transiently occluded constant velocity (Experiment 1) or accelerating (Experiment 2) targets. Velocity characteristics and occlusion duration were arranged in random or blocked order, thus permitting a novel examination of the contribution from sensorimotor signals and predictive processes acting within the ocular system during transient occlusion.

The influence of cues and stimulus history on the non-linear frequency characteristics of the pursuit response to randomized target motion.

When humans pursue motion stimuli composed of alternating constant velocity segments of randomised duration (RD), they nevertheless initiate anticipatory eye deceleration before stimulus direction changes at a pre-programmed time based on averaging prior stimulus timing. We investigated, in both the time and frequency domains, how averaging interacts with deceleration cues by comparing responses to stimuli composed of segments that were either constant-velocity ramps or half-cycle sinusoids. RDs were randomized within 6 ranges, each comprising 8 RDs and having differing mean RD.

The neural correlates of inhibiting pursuit to smoothly moving targets.

A previous study has shown that actively pursuing a moving target provides a predictive motor advantage when compared with passive observation of the moving target while keeping the eyes still [Burke, M. R., & Barnes, G.

The interaction of visual, vestibular and extra-retinal mechanisms in the control of head and gaze during head-free pursuit.

The ability to co-ordinate the eyes and head when tracking moving objects is important for survival. Tracking with eyes alone is controlled by both visually dependent and extra-retinal mechanisms, the latter sustaining eye movement during target extinction. We investigated how the extra-retinal component develops at the beginning of randomised responses during head-free pursuit and how it interacts with the vestibulo-ocular reflex (VOR).

Extraction of visual motion information for the control of eye and head movement during head-free pursuit.

We investigated how effectively briefly presented visual motion could be assimilated and used to track future target motion with head and eyes during target disappearance. Without vision, continuation of eye and head movement is controlled by internal (extra-retinal) mechanisms, but head movement stimulates compensatory vestibulo-ocular reflex (VOR) responses that must be countermanded for gaze to remain in the direction of target motion. We used target exposures of 50-200 ms at the start of randomised step-ramp stimuli, followed by > 400 ms of target disappearance, to investigate the ability to sample target velocity and subsequently generate internally controlled responses.

Oscillatory eye movements resembling pendular nystagmus in normal juvenile macaques.

Purpose: Juvenile monkeys being trained on smooth-pursuit tasks exhibit ocular oscillations resembling pendular nystagmus. The purpose of this study was to analyze these oscillations, the effects of gabapentin on them, and responses of cerebellar floccular neurons to understand possible neuronal mechanisms.

Methods: Four monkeys were trained for horizontal and vertical smooth pursuit; in two, saccades were also tested.

Oculomotor prediction of accelerative target motion during occlusion: long-term and short-term effects.

The present study examined the influence of long-term (i.e., between-trial) and short-term (i.

Predicting the unpredictable: weighted averaging of past stimulus timing facilitates ocular pursuit of randomly timed stimuli.

In motor control, prediction of future events is vital for overcoming sensory-motor processing delays and facilitating rapid and accurate responses in a dynamic environment. In human ocular pursuit this is so pervasive that prediction of future target motion cannot easily be eliminated by randomizing stimulus parameters. We investigated the prediction of temporally randomized events during pursuit of alternating constant-velocity (ramp) stimuli in which the timing of direction changes varied unpredictably over a given range.

Target acceleration can be extracted and represented within the predictive drive to ocular pursuit.

Given sufficient exposure to stimulus presentation, the oculomotor system generates a representation of the stimulus characteristics, which is then used to predict the upcoming target motion. In addition to compensating for the perceptual-motor delay, these predictive processes perpetuate eye motion during a transient occlusion and compensate for the loss of visual input. At present, however, it is not well understood whether and how the oculomotor system extracts and represents target acceleration for subsequent predictive control.

Sequence learning in two-dimensional smooth pursuit eye movements in humans.

Sequence learning is common to all motor systems and is an essential aspect of human behavior necessary for the acquisition of motor skill. Many previous studies have demonstrated the ability to observe, store, and repeat sequences in a variety of modalities resulting in reduced reaction time. Recently, it has been found that subjects can make predictive smooth eye movements to a sequence of discrete horizontal target motions (C.

Smooth ocular pursuit during the transient disappearance of an accelerating visual target: the role of reflexive and voluntary control.

This study examined the extent to which human subjects predict future target motion for the control of smooth ocular pursuit. Subjects were required to pursue an accelerating target (0, 4 or 8 degrees/s2) that underwent a transient occlusion, and consequently reappeared with the same or increased velocity. Presentations were received in a random or blocked order.

Combined smooth and saccadic ocular pursuit during the transient occlusion of a moving visual object.

Accurate ocular pursuit during a transient occlusion interval would minimize retinal position and velocity error, and could provide an advantage when discriminating object characteristics at reappearance. This study was designed to examine how the smooth and saccadic response extrapolates the trajectory of a moving visual object during a transient occlusion. We confirmed that subjects could not maintain unity gain smooth pursuit during the transient occlusion.

Evidence for synergy between saccades and smooth pursuit during transient target disappearance.

Visual tracking of moving objects requires prediction to compensate for visual delays and minimize mismatches between eye and target position and velocity. In everyday life, objects often disappear behind an occluder, and prediction is required to align eye and target at reappearance. Earlier studies investigating eye motion during target blanking showed that eye velocity first decayed after disappearance but was sustained or often recovered in a predictive way.

The use of non-motion-based cues to pre-programme the timing of predictive velocity reversal in human smooth pursuit.

Human smooth pursuit eye movements are principally driven by visual feedback and cannot normally be initiated at will. However, when tracking periodic motion, smooth eye movements reverse direction prior to target reversal, driven by anticipation, not visual feedback. Here, we investigate cognitive control over such eye reversals.

Timing the anticipatory recovery in smooth ocular pursuit during the transient disappearance of a visual target.

After the disappearance of a moving target and the loss of visual feedback regarding image motion, smooth pursuit eye velocity decays rapidly. If, however, there is an expectation the target will reappear further along its trajectory, there is a scaled recovery in eye velocity before target reappearance. The aim of this study was to examine whether the timing of the anticipatory recovery is influenced by the duration of transient target disappearance.

Predictive smooth ocular pursuit during the transient disappearance of a visual target.

When a moving target disappears and there is a complete absence of visual feedback signals, eye velocity decays rapidly but often recovers to previous levels if there is an expectation the target will reappear further along its trajectory Given that eye velocity cannot be maintained under such circumstances, the anticipatory recovery may function to minimize the developing velocity error. When there is a change in target velocity during a transient, any recovery should ideally be scaled and hence predictive of the expected target velocity at reappearance. This study confirmed that subjects did not maintain eye velocity close to target velocity for the duration of the inter-stimulus interval (ISI).