Visual Cortical Function Changes After Perceptual Learning with Dichoptic Attention Tasks in Adults with Amblyopia: A Case Study Evaluated Using fMRI.

Amblyopia is a neurodevelopmental disorder of vision, commonly caused by strabismus or anisometropia during early childhood. While studies demonstrated that perceptual learning improves visual acuity and stereopsis in adults with amblyopia, accompanying changes in visual cortical function remain unclear. We measured functional magnetic resonance imaging (fMRI) responses before and after perceptual learning in seven adults with amblyopia.

Touch to text: Spatiotemporal evolution of braille letter representations in blind readers.

Visual deprivation does not silence the visual cortex, which is responsive to auditory, tactile, and other nonvisual tasks in blind persons. However, the underlying functional dynamics of the neural networks mediating such crossmodal responses remain unclear. Here, using braille reading as a model framework to investigate these networks, we presented sighted (N=13) and blind (N=12) readers with individual visual print and tactile braille alphabetic letters, respectively, during MEG recording.

The digital signature of emergent tremor in Parkinson's disease.

Emergent tremor in Parkinson's disease (PD) can occur during sustained postures or movements that are different from action tremor. Tremor can contaminate the clinical rating of bradykinesia during finger tapping. Currently, there is no reliable way of isolating emergent tremor and measuring the cardinal motor symptoms based on voluntary movements only.

Smooth pursuit deficits impact dynamic visual acuity in macular degeneration.

Significance: Prior studies with large, highly visible targets report low smooth pursuit gains in individuals with macular degeneration (MD). We show that lower gains persist even when observers are pursuing a target that requires discrimination at the acuity limit. This low gain causes retinal slip, potentially leading to motion blur and target disappearance in the scotoma, which further compromise the visibility of moving object.

Co-Designing Auditory Navigation Solutions for Traveling as a Blind Individual During the COVID-19 Pandemic.

A group co-design was held in March 2021 with six blind and low-vision individuals (BLIs) from the United States. Participants were asked to discuss problems related to travel during the COVID-19 pandemic and make recommendations for possible solutions. Two probes (prototypes) of a non-visual neighborhood travel map and a non-visual COVID-19 choropleth map (a map using colors or sounds over each state to represent different values) of COVID-19 state data were shown to participants for inspiration.

Visual Field Dependence Persists in Age-Related Central Visual Field Loss.

Purpose: To examine whether the age-related increase in visual field dependence persists in older adults with central field loss (CFL).

Methods: Twenty individuals with CFL were grouped into participants with age-related binocular CFL (CFL, n = 9), age-related monocular CFL/relative scotomata (mCFL, n = 8), and CFL occurring at a young age (yCFL, n = 3). Seventeen controls were age-matched to the older CFL groups (OA) and three to the yCFL group (yOA).

A new approach to measure interocular suppression in amblyopia and strabismus.

Interocular suppression is commonly estimated by the contrast "balance point" between the eyes in individuals with amblyopia, in which the depth of suppression is defined as the increased contrast in the amblyopic eye that is perceptually matched to the fellow eye. However, this method may not be suitable for individuals with strabismus who have normal or even better contrast sensitivity in the non-fixating eye. In this study, I introduced a new approach that can be used for measuring interocular suppression for both amblyopia and strabismus without balancing contrasts between the eyes.

A Comparison of Walking Behavior during the Instrumented TUG and Habitual Gait.

The timed up and go test (TUG) is a common clinical functional balance test often used to complement findings on sensorimotor changes due to aging or sensory/motor dysfunction. The instrumented TUG can be used to obtain objective postural and gait measures that are more sensitive to mobility changes. We investigated whether gait and body coordination during TUG is representative of walking.

Noise estimation for head-mounted 3D binocular eye tracking using Pupil Core eye-tracking goggles.

Head-mounted, video-based eye tracking is becoming increasingly common and has promise in a range of applications. Here, we provide a practical and systematic assessment of the sources of measurement uncertainty for one such device - the Pupil Core - in three eye-tracking domains: (1) the 2D scene camera image; (2) the physical rotation of the eye relative to the scene camera 3D space; and (3) the external projection of the estimated gaze point location onto the target plane or in relation to world coordinates. We also assess eye camera motion during active tasks relative to the eye and the scene camera, an important consideration as the rigid arrangement of eye and scene camera is essential for proper alignment of the detected gaze.

ISCEV guidelines for calibration and verification of stimuli and recording instruments (2023 update).

This document developed by the International Society for Clinical Electrophysiology of Vision (ISCEV) provides guidance for calibration and verification of stimulus and recording systems specific to clinical electrophysiology of vision. This guideline provides additional information for those using ISCEV Standards and Extended protocols and supersedes earlier Guidelines. The ISCEV guidelines for calibration and verification of stimuli and recording instruments (2023 update) were approved by the ISCEV Board of Directors 01, March 2023.

Peripheral targets attenuate miniature eye movements during fixation.

Fixating a small dot is a universal technique for stabilizing gaze in vision and eye movement research, and for clinical imaging of normal and diseased retinae. During fixation, microsaccades and drifts occur that presumably benefit vision, yet microsaccades compromise image stability and usurp task attention. Previous work suggested that microsaccades and smooth pursuit catch-up saccades are controlled by similar mechanisms.

Bradykinesia and Its Progression Are Related to Interhemispheric Beta Coherence.

Objective: Bradykinesia is the major cardinal motor sign of Parkinson disease (PD), but its neural underpinnings are unclear. The goal of this study was to examine whether changes in bradykinesia following long-term subthalamic nucleus (STN) deep brain stimulation (DBS) are linked to local STN beta (13-30 Hz) dynamics or a wider bilateral network dysfunction.

Methods: Twenty-one individuals with PD implanted with sensing neurostimulators (Activa® PC + S, Medtronic, PLC) in the STN participated in a longitudinal 'washout' therapy study every three to 6 months for an average of 3 years.

Non-Visual Access to an Interactive 3D Map.

Maps are indispensable for helping people learn about unfamiliar environments and plan trips. While tactile (2D) and 3D maps offer non-visual map access to people who are blind or visually impaired (BVI), this access is greatly enhanced by adding interactivity to the maps: when the user points at a feature of interest on the map, the name and other information about the feature is read aloud in audio. We explore how the use of an interactive 3D map of a playground, containing over seventy play structures and other features, affects spatial learning and cognition.

A novel method for utilizing dichoptic attention tasks in amblyopic training.

There is converging evidence of attention deficits in individuals with amblyopia. It has been reported that selective visual attention is allocated preferentially toward the non-amblyopic fellow eye in strabismic ambloypes. This attention allocation bias between the eyes is found related to visual suppression in amblyopia.

Quantitative Digitography Measures Motor Symptoms and Disease Progression in Parkinson's Disease.

Background: Assessment of motor signs in Parkinson's disease (PD) requires an in-person examination. However, 50% of people with PD do not have access to a neurologist. Wearable sensors can provide remote measures of some motor signs but require continuous monitoring for several days.

Perceptual learning with dichoptic attention tasks improves attentional modulation in V1 and IPS and reduces interocular suppression in human amblyopia.

Long-term and chronic visual suppression to the non-preferred eye in early childhood is a key factor in developing amblyopia, as well as a critical barrier to treat amblyopia. To explore the relationship between selective visual attention and amblyopic suppression and its role in the success of amblyopic training, we used EEG source-imaging to show that training human adults with strabismic and anisometropic amblyopia with dichoptic attention tasks improved attentional modulation of neural populations in the primary visual cortex (V1) and intraparietal sulcus (IPS). We also used psychophysics to show that training reduced interocular suppression along with visual acuity and stereoacuity improvements.

Do we enjoy what we sense and perceive? A dissociation between aesthetic appreciation and basic perception of environmental objects or events.

This integrative review rearticulates the notion of human aesthetics by critically appraising the conventional definitions, offerring a new, more comprehensive definition, and identifying the fundamental components associated with it. It intends to advance holistic understanding of the notion by differentiating aesthetic perception from basic perceptual recognition, and by characterizing these concepts from the perspective of information processing in both visual and nonvisual modalities. To this end, we analyze the dissociative nature of information processing in the brain, introducing a novel local-global integrative model that differentiates aesthetic processing from basic perceptual processing.

Perception and Appreciation of Tactile Objects: The Role of Visual Experience and Texture Parameters.

This exploratory study was designed to examine the effects of visual experience and specific texture parameters on both discriminative and aesthetic aspects of tactile perception. To this end, the authors conducted two experiments using a novel behavioral (ranking) approach in blind and (blindfolded) sighted individuals. Groups of congenitally blind, late blind, and (blindfolded) sighted participants made relative stimulus preference, aesthetic appreciation, and smoothness or softness judgment of two-dimensional (2D) or three-dimensional (3D) tactile surfaces through active touch.

Higher Visual Function Deficits in Children With Cerebral Visual Impairment and Good Visual Acuity.

In clinical practice Cerebral Visual Impairment (CVI) is typically diagnosed by observation of abnormal visually guided behaviors which indicate higher visual function deficits (HVFDs) suggesting abnormal brain development or brain damage in a child with a suitable clinical history. HVFDs can occur even in the presence of good visual acuity and may remain undiagnosed the good visual acuity does not prompt further investigation. This leads to a lack of understanding of the child's visual perceptual difficulties.

Lack of progression of beta dynamics after long-term subthalamic neurostimulation.

Objective: To investigate the progression of neural and motor features of Parkinson's disease in a longitudinal study, after washout of medication and bilateral subthalamic nucleus deep brain stimulation (STN DBS).

Methods: Participants with clinically established Parkinson's disease underwent bilateral implantation of DBS leads (18 participants, 13 male) within the STN using standard functional frameless stereotactic technique and multi-pass microelectrode recording. Both DBS leads were connected to an implanted investigative sensing neurostimulator (Activa™ PC + S, Medtronic, PLC).

Neuroplasticity and Crossmodal Connectivity in the Normal, Healthy Brain.

Objective: Neuroplasticity enables the brain to establish new crossmodal connections or reorganize old connections which are essential to perceiving a multisensorial world. The intent of this review is to identify and summarize the current developments in neuroplasticity and crossmodal connectivity, and deepen understanding of how crossmodal connectivity develops in the normal, healthy brain, highlighting novel perspectives about the principles that guide this connectivity.

Methods: To the above end, a narrative review is carried out.

A covered eye fails to follow an object moving in depth.

To clearly view approaching objects, the eyes rotate inward (vergence), and the intraocular lenses focus (accommodation). Current ocular control models assume both eyes are driven by unitary vergence and unitary accommodation commands that causally interact. The models typically describe discrete gaze shifts to non-accommodative targets performed under laboratory conditions.

Eye Movements in Macular Degeneration.

In healthy vision, the fovea provides high acuity and serves as the locus for fixation achieved through saccadic eye movements. Bilateral loss of the foveal regions in both eyes causes individuals to adopt an eccentric locus for fixation. This review deals with the eye movement consequences of the loss of the foveal oculomotor reference and the ability of individuals to use an eccentric fixation locus as the new oculomotor reference.