The receptive field construction of midget ganglion cells in primate retina.

The midget pathway of the primate retina provides the visual system with the foundations for high spatial resolution and color perception. An essential contributor to these properties is center-surround organization, in which responses from the central area of a cell's receptive field are antagonized by responses from a surrounding area. Two key questions about center-surround organization are unresolved.

Thyroid disease in cervical dystonia.

There are many possible etiologies for cervical dystonia (CD), but a cause cannot be identified in most cases. Most recent attention has focused on genetic causes, although a few prior studies have highlighted autoimmune mechanisms instead. Because autoimmune disorders frequently co-exist, the current study evaluated the hypothesis that autoimmune disorders might be more common in CD than neurological controls.

A model for the development of binocular congruence in primary visual cortex.

Neurons in primary visual cortex are selective for stimulus orientation, and a neuron's preferred orientation changes little when the stimulus is switched from one eye to the other. It has recently been shown that monocular orientation preferences are uncorrelated before eye opening; how, then, do they become aligned during visual experience? We aimed to provide a model for this acquired congruence. Our model, which simulates the cat's visual system, comprises multiple on-centre and off-centre channels from both eyes converging onto neurons in primary visual cortex; development proceeds in two phases via Hebbian plasticity in the geniculocortical synapse.

A Multi-center Genome-wide Association Study of Cervical Dystonia.

Background: Several monogenic causes for isolated dystonia have been identified, but they collectively account for only a small proportion of cases. Two genome-wide association studies have reported a few potential dystonia risk loci; but conclusions have been limited by small sample sizes, partial coverage of genetic variants, or poor reproducibility.

Objective: To identify robust genetic variants and loci in a large multicenter cervical dystonia cohort using a genome-wide approach.

A metabolomic study of cervical dystonia.

Introduction: Cervical dystonia is the most common of the adult-onset focal dystonias. Most cases are idiopathic. The current view is that cervical dystonia may be caused by some combination of genetic and environmental factors.

A Model for the Origin of Motion Direction Selectivity in Visual Cortex.

Motion perception is a vital part of our sensory repertoire in that it contributes to navigation, awareness of moving objects, and communication. Motion sense in carnivores and primates originates with primary visual cortical neurons selective for motion direction. More than 60 years after the discovery of these neurons, there is still no consensus on the mechanism underlying direction selectivity.

A model for the origin and development of visual orientation selectivity.

Orientation selectivity is a key property of primary visual cortex that contributes, downstream, to object recognition. The origin of orientation selectivity, however, has been debated for decades. It is known that on- and off-centre subcortical pathways converge onto single neurons in primary visual cortex, and that the spatial offset between these pathways gives rise to orientation selectivity.

Motion changes response balance between ON and OFF visual pathways.

Humans are faster at detecting dark than light stationary stimuli, a temporal difference that originates early in the visual pathway. Here we show that this difference reverses when stimuli move, making detection faster for moving lights than darks. Human subjects judged the direction of moving edges and bars, and made faster and more accurate responses for light than for dark stimuli.

Pilot Single-Blind Trial of AbobotulinumtoxinA in Oromandibular Dystonia.

Oromandibular dystonia (OMD) causes involuntary movements of masticatory and lingual muscles impairing eating, speaking, and swallowing. Treatment options are limited. The objective of this study was to determine the safety and efficacy of abobotulinumtoxinA (aboBoNTA) in OMD.

Affective Correlates of Psychosis in Parkinson's Disease.

Objective: To examine the nature of the association between affective disorders and psychosis in Parkinson's disease (PD).

Background: In PD, psychosis and affective disorders are common and independently impact quality of life and mortality. Both depression and psychosis are correlated with the occurrence of cognitive dysfunction, suggesting that they may share neurobiological substrates.

Orientation discrimination requires coactivation of on- and off-dominated visual channels.

Orientation sensitivity depends on the cortical convergence of on- and off-center subcortical neurons. Off-center inputs are faster and stronger than their on-center counterparts: How does this asymmetry affect orientation discrimination? We tackled this question psychophysically with grating stimuli that either increased or decreased luminance. The gratings were of low contrast in order to avoid the complicating influences of nonlinearities such as response saturation, masking, and aftereffects.

A Functional Magnetic Resonance Imaging Study of Head Movements in Cervical Dystonia.

Cervical dystonia (CD) is a neurological disorder characterized by abnormal movements and postures of the head. The brain regions responsible for these abnormal movements are not well understood, because most imaging techniques for assessing regional brain activity cannot be used when the head is moving. Recently, we mapped brain activation in healthy individuals using functional magnetic resonance imaging during isometric head rotation, when muscle contractions occur without actual head movements.

Botulinum toxin treatment failures in cervical dystonia: causes, management, and outcomes.

Botulinum toxin (BoNT) is highly effective in the treatment of cervical dystonia (CD), yet a significant proportion of patients report low levels of satisfaction following treatment and fail to follow up for repeated treatments. The goal of this study was to determine the reasons that some patients have unsatisfactory responses. A total of 35 subjects who came to our center requesting alternative treatments due to unsatisfactory responses following BoNT treatment for CD were evaluated.

Ocular palatal tremor plus dystonia - new syndromic association.

Objective: Ocular palatal tremor typically develops after a breach in the Guillian-Mollaret triangle. We herein describe a variant of this syndrome in which dystonia is also present, hence called, here, ocular palatal tremor plus dystonia.

Methods: We assessed eye-head movements and dystonia in six patients with ocular palatal plus dystonia.

Chronic and acute biases in perceptual stabilization.

When perceptually ambiguous stimuli are presented intermittently, the percept on one presentation tends to be the same as that on the previous presentation. The role of short-term, acute biases in the production of this perceptual stability is relatively well understood. In addition, however, long-lasting, chronic bias may also contribute to stability.

Cognitive correlates of hallucinations and delusions in Parkinson's disease.

Background: Hallucinations and delusions that complicate Parkinson's disease (PD) could lead to nursing home placement and are linked to increased mortality. Cognitive impairments are typically associated with the presence of hallucinations but there are no data regarding whether such a relationship exists with delusions.

Objective: We hypothesized that hallucinations would be associated with executive and visuospatial disturbance.

Temporal profile of improvement of tardive dystonia after globus pallidus deep brain stimulation.

Background: Several case reports and small series have indicated that tardive dystonia is responsive to globus pallidus deep brain stimulation. Whether different subtypes or distributions of tardive dystonia are associated with different outcomes remains unknown.

Methods: We assessed the outcomes and temporal profile of improvement of eight tardive dystonia patients who underwent globus pallidus deep brain stimulation over the past six years through record review.

Globus pallidus deep brain stimulation for adult-onset axial dystonia.

Introduction: Generalized dystonia, both primary and secondary forms, and axial dystonias such as tardive dystonia, and idiopathic cervical dystonia are responsive to globus pallidus interna (GPi) DBS. There is a paucity of investigations probing the impact of DBS on adult-onset axial dystonia. We assessed the efficacy of GPi DBS in four patients with rare adult-onset axial dystonia.

Measuring perception without introspection.

Binocular rivalry, the perceptual alternation between incompatible monocular stimuli, is conventionally measured by asking the subject which percept is currently visible. This is problematic because the response is unverifiable, open to response bias, and falsely assumes that the perceptual experience is binary. We overcame these limitations in a new approach that does not require subjective reporting of perceptual state.

An ¹⁸F-FDG PET study of cervical muscle in parkinsonian anterocollis.

The underlying etiology of parkinsonian anterocollis has been the subject of recent debate. The purpose of this study is to test the hypothesis that anterocollis in parkinsonian syndromes is associated with dystonia of the deep cervical flexors (longus colli and capitis). Eight patients with anterocollis, six in the setting of parkinsonism and two primary cervical dystonia control subjects with anterocollis underwent prospective structured clinical evaluations (interview, examination and rating scales), systematic electromyography of the cervical extensor musculature and (18)F-FDG PET/CT studies of cervical muscles to examine evidence of hypermetabolism or overactivity of deep cervical flexors.

Motions add, orientations don't, in the human visual system.

Humans can distinguish between contours of similar orientation, and between directions of visual motion. There is consensus that both of these capabilities depend on selective activation of tuned neural channels. The bandwidths of these tuned channels are estimated here by modelling previously published empirical data.

How long does it take to diagnose cervical dystonia?

Background: Dystonia is a neurological disorder characterized by involuntary twisting movements and postures. The neck is among the most commonly affected regions, and diagnosis can be made readily through a simple clinical evaluation. The goal of this study was to explore how long it took patients to receive a diagnosis of cervical dystonia after symptom onset.

Sleep and impulsivity in Parkinson's disease.

Background: Impulsive behavior and poor sleep are important non-motor features of Parkinson's disease (PD) that negatively impact the quality of life of patients and their families. Previous research suggests a higher level of sleep complaints in PD patients who demonstrate impulsive behaviors, but the nature of the sleep disturbances has yet to be comprehensively tested.

Methods: Consecutive idiopathic PD patients (N = 143) completed the Minnesota Impulse Disorder Interview and a sleep questionnaire that assessed sleep efficiency, excessive daytime sleepiness, restless legs symptoms, snoring, dreams/nightmares, and nocturia.

Daytime REM sleep in Parkinson's disease.

Background: Previous studies have demonstrated both clinical and neurochemical similarities between Parkinson's disease (PD) and narcolepsy. The intrusion of REM sleep into the daytime remains a cardinal feature of narcolepsy, but the importance of these intrusions in PD remains unclear. In this study we examined REM sleep during daytime Maintenance of Wakefulness Testing (MWT) in PD patients.