The motion-induced shift in the perceived location of a grating also shifts its aftereffect.

Motion can bias the perceived location of a stationary stimulus (Whitney & Cavanagh, 2000), but whether this occurs at a high level of representation or at early, retinotopic stages of visual processing remains an open question. As coding of orientation emerges early in visual processing, we tested whether motion could influence the spatial location at which orientation adaptation is seen. Specifically, we examined whether the tilt aftereffect (TAE) depends on the perceived or the retinal location of the adapting stimulus, or both.

Optimization and comparison of balloon-based partial breast brachytherapy using a single source, a standard plan line source, and both forward and inverse planned multilumen techniques.

Purpose: This study directly compares four dosimetric techniques for balloon-based partial breast brachytherapy: single source, standard line source, and both forward planned and inverse planned multilumen (ML). A standard line source plan is presented to be used in a single catheter or as a starting point for forward planned ML.

Methods And Materials: The study population consists of 12 patients previously treated with a single lumen.

Perceiving group behavior: sensitive ensemble coding mechanisms for biological motion of human crowds.

Many species, including humans, display group behavior. Thus, perceiving crowds may be important for social interaction and survival. Here, we provide the first evidence that humans use ensemble-coding mechanisms to perceive the behavior of a crowd of people with surprisingly high sensitivity.

Reference repulsion in the categorical perception of biological motion.

Perceiving biological motion is important for understanding the intentions and future actions of others. Perceiving an approaching person's behavior may be particularly important, because such behavior often precedes social interaction. To this end, the visual system may devote extra resources for perceiving an oncoming person's heading.

Crowd perception in prosopagnosia.

Prosopagnosics, individuals who are impaired at recognizing single faces, often report increased difficulty when confronted with crowds. However, the discrimination of crowds has never been fully tested in the prosopagnosic population. Here we investigate whether developmental prosopagnosics can extract ensemble characteristics from groups of faces.

The frozen face effect: why static photographs may not do you justice.

When a video of someone speaking is paused, the stationary image of the speaker typically appears less flattering than the video, which contained motion. We call this the frozen face effect (FFE). Here we report six experiments intended to quantify this effect and determine its cause.

The perceived position of moving objects: transcranial magnetic stimulation of area MT+ reduces the flash-lag effect.

How does the visual system assign the perceived position of a moving object? This question is surprisingly complex, since sluggish responses of photoreceptors and transmission delays along the visual pathway mean that visual cortex does not have immediate information about a moving object's position. In the flash-lag effect (FLE), a moving object is perceived ahead of an aligned flash. Psychophysical work on this illusion has inspired models for visual localization of moving objects.

An aftereffect of adaptation to mean size.

The visual system rapidly represents the mean size of sets of objects. Here, we investigated whether mean size is explicitly encoded by the visual system, along a single dimension like texture, numerosity, and other visual dimensions susceptible to adaptation. Observers adapted to two sets of dots with different mean sizes, presented simultaneously in opposite visual fields.

Ultrafine spatial acuity of blind expert human echolocators.

Echolocating organisms represent their external environment using reflected auditory information from emitted vocalizations. This ability, long known in various non-human species, has also been documented in some blind humans as an aid to navigation, as well as object detection and coarse localization. Surprisingly, our understanding of the basic acuity attainable by practitioners-the most fundamental underpinning of echoic spatial perception-remains crude.

A flash-drag effect in random motion reveals involvement of preattentive motion processing.

The flash-drag (FDE) effect refers to the phenomenon in which the position of a stationary flashed object in one location appears shifted in the direction of nearby motion. Over the past decade, it has been debated how bottom-up and top-down processes contribute to this illusion. In this study, we demonstrate that randomly phase-shifting gratings can produce the FDE.

A conformational switch in the CRIB-PDZ module of Par-6.

Here, we report a novel mechanism of PDZ (PSD-95/Dlg/ZO-1) domain regulation that distorts a conserved element of PDZ ligand recognition. The polarity regulator Par-6 assembles a conserved multiprotein complex and is directly modulated by the Rho GTPase Cdc42. Cdc42 binds the adjacent Cdc42/Rac interactive binding (CRIB) and PDZ domains of Par-6, increasing C-terminal ligand binding affinity by 10-fold.

Resolution of spatial and temporal visual attention in infants with fragile X syndrome.

Fragile X syndrome is the most common cause of inherited intellectual impairment and the most common single-gene cause of autism. Individuals with fragile X syndrome present with a neurobehavioural phenotype that includes selective deficits in spatiotemporal visual perception associated with neural processing in frontal-parietal networks of the brain. The goal of the current study was to examine whether reduced resolution of spatial and/or temporal visual attention may underlie perceptual deficits related to fragile X syndrome.

Stress and mental disorders in female military personnel: comparisons between the sexes in a male dominated profession.

The proportion of women in militaries is growing; however, many studies in the area of military mental health have been conducted with majority male samples. The present study examined sex differences in trauma exposure, work stress, and mental disorders in the Canadian Community Health Survey - Canadian Forces Supplement, a representative sample of 5155 regular force personnel and 3286 reservists ages 16-54. Past-year DSM-IV mental disorders (depression, generalized anxiety disorder, panic disorder, social phobia, PTSD, and alcohol dependence), lifetime exposure to 28 traumatic events, and work stress were assessed.

Conversion of the enzyme guanylate kinase into a mitotic-spindle orienting protein by a single mutation that inhibits GMP-induced closing.

New protein functions can require complex sequence changes, but the minimal path is not well understood. The guanylate kinase enzyme (GK(enz)), which catalyzes phosphotransfer from ATP to GMP, evolved into the GK domain (GK(dom)), a protein-binding domain found in membrane associate guanylate kinases that function in mitotic spindle orientation and cell adhesion. Using an induced polarity assay for GK(dom) function, we show that a single serine to proline mutation is sufficient to switch extant GK(enz) into a functional GK(dom).

Neural correlates of coherent and biological motion perception in autism.

Recent evidence suggests those with autism may be generally impaired in visual motion perception. To examine this, we investigated both coherent and biological motion processing in adolescents with autism employing both psychophysical and fMRI methods. Those with autism performed as well as matched controls during coherent motion perception but had significantly higher thresholds for biological motion perception.

Efficient summary statistical representation when change localization fails.

People are sensitive to the summary statistics of the visual world (e.g., average orientation/speed/facial expression).

Time crawls: the temporal resolution of infants' visual attention.

Conscious visual perception of the constantly changing environment is one of the brain's most critical functions. In virtually every moment of every daily activity, the visual system is confronted with the task of accurately representing and interpreting scenes that change rapidly over time. Adults can judge the identity and order of changing images presented at a rate of up to 10 Hz (~50 ms per image); this limit reflects a finite temporal resolution of attention.

Object-level visual information gets through the bottleneck of crowding.

Natural visual scenes are cluttered. In such scenes, many objects in the periphery can be crowded, blocked from identification, simply because of the dense array of clutter. Outside of the fovea, crowding constitutes the fundamental limitation on object recognition and is thought to arise from the limited resolution of the neural mechanisms that select and bind visual features into coherent objects.

Perceived positions determine crowding.

Crowding is a fundamental bottleneck in object recognition. In crowding, an object in the periphery becomes unrecognizable when surrounded by clutter or distractor objects. Crowding depends on the positions of target and distractors, both their eccentricity and their relative spacing.

The acuity of echolocation: Spatial resolution in the sighted compared to expert performance.

Compared with the echolocation performance of a blind expert, sighted novices rapidly learned size and position discrimination with surprising precision. We use a novel task to characterize the population distribution of echolocation skill in the sighted and report the highest known human echolocation acuity in our expert subject.

Visual crowding: a fundamental limit on conscious perception and object recognition.

Crowding, the inability to recognize objects in clutter, sets a fundamental limit on conscious visual perception and object recognition throughout most of the visual field. Despite how widespread and essential it is to object recognition, reading and visually guided action, a solid operational definition of what crowding is has only recently become clear. The goal of this review is to provide a broad-based synthesis of the most recent findings in this area, to define what crowding is and is not, and to set the stage for future work that will extend our understanding of crowding well beyond low-level vision.

Voluntary attention modulates motion-induced mislocalization.

When a test is flashed on top of two superimposed, opposing motions, the perceived location of the test is shifted in opposite directions depending on which of the two motions is attended. Because the stimulus remains unchanged as attention switches from one motion to the other, the effect cannot be due to stimulus-driven, low-level motion. A control condition ruled out any contribution from possible attention-induced cyclotorsion of the eyes.

Comparison of BD Bactec Plus blood culture media to VersaTREK Redox blood culture media for detection of bacterial pathogens in simulated adult blood cultures containing therapeutic concentrations of antibiotics.

Antibiotic neutralization in blood culture media from two automated systems was evaluated by measuring the recovery of organisms and times to detection in simulated cultures. Overall, BD Bactec Plus media (Bactec FX system) outperformed TREK 80 ml Redox media (VersaTREK system), although results suggest a relative rather than an absolute increased rate of recovery for the Bactec media.

Reexamining the possible benefits of visual crowding: dissociating crowding from ensemble percepts.

Peripheral objects and their features become indistinct when closely surrounding but nonoverlapping objects are present. Most models suggest that this phenomenon, called crowding, reflects limitations of visual processing, but an intriguing idea is that it may be, in part, adaptive. Specifically, the mechanism generating crowding may simultaneously facilitate ensemble representations of features, leaving meaningful information about clusters of objects.