Anxiety provokes balance deficits that are selectively dopa-responsive in Parkinson's disease.

Previous research has suggested that balance impairments may be linked to anxiety in PD, yet there is little empirical evidence to support this link in PD. This study aimed to evaluate the influence of anxiety on balance, and also examine whether dopaminergic treatment modulates the influence of anxiety on balance. Forty-two participants (10 high anxious PD [HA-PD]; 11 low anxious PD [LA-PD], 21 controls [HC]) performed 10 quiet standing trials on a force platform in two virtual environments: LOW threat; on a plank located on the ground; HIGH threat; on an elevated plank.

Evaluating the Link Between Dopaminergic Treatment, Gait Impairment, and Anxiety in Parkinson's Disease.

Background: Anxiety is the most under-recognized nonmotor symptom of Parkinson's disease (PD), yet it is unclear whether motor impairment exacerbates anxiety observed in PD, or vice versa. The current study examined: (1) whether movement (i.e.

Virtually-induced threat in Parkinson's: Dopaminergic interactions between anxiety and sensory-perceptual processing while walking.

Research evidence has suggested that anxiety influences gait in PD, with an identified dopa-sensitive gait response in highly anxious PD. It has been well-established that accurate perception of the environment and sensory feedback is essential for gait. Arguably since sensory and perceptual deficits have been noted in PD, anxiety has the potential to exacerbate movement impairments, since one might expect that reducing resources needed to overcome or compensate for sensory-perceptual deficits may lead to even more severe gait impairments.

Anxiety-provoked gait changes are selectively dopa-responsive in Parkinson's disease.

In order to understand how dopamine modulates the effect of anxiety on gait, the goal of this study was to use virtual reality to provoke anxiety in Parkinson's disease (PD) (in both ON and OFF states) and quantify its effect on gait. Seventeen participants with PD and 20 healthy age-matched controls were instructed to walk in a virtual environment in two anxiety-provoking conditions: (i) across a plank that was located on the GROUND and (ii) across an ELEVATED plank. All participants with PD completed this experiment in both the ON and OFF states, and were then striated into groups based on baseline trait anxiety scores for further analyses.

Does manipulating the speed of visual flow in virtual reality change distance estimation while walking in Parkinson's disease?

Although dopaminergic replacement therapy is believed to improve sensory processing in PD, while delayed perceptual speed is thought to be caused by a predominantly cholinergic deficit, it is unclear whether sensory-perceptual deficits are a result of corrupt sensory processing, or a delay in updating perceived feedback during movement. The current study aimed to examine these two hypotheses by manipulating visual flow speed and dopaminergic medication to examine which influenced distance estimation in PD. Fourteen PD and sixteen HC participants were instructed to estimate the distance of a remembered target by walking to the position the target formerly occupied.

Does anxiety cause freezing of gait in Parkinson's disease?

Individuals with Parkinson's disease (PD) commonly experience freezing of gait under time constraints, in narrow spaces, and in the dark. One commonality between these different situations is that they may all provoke anxiety, yet anxiety has never been directly examined as a cause of FOG. In this study, virtual reality was used to induce anxiety and evaluate whether it directly causes FOG.

Dopaminergic contributions to distance estimation in Parkinson's disease: a sensory-perceptual deficit?

Recent research has found that perceptual deficits exist in Parkinson's disease (PD), yet the link between perception and movement impairments is not well understood. Inaccurate estimation of distance has the potential to be an underlying cause of movement impairments. Alternatively, those with PD may not be able to perceive their own movements accurately.

Functional analysis of concealment: a novel application of prospect and refuge theory.

According to prospect-refuge theory, humans prefer environments that afford protection from threat (refuge), but also provide large fields of view (prospect). Prospect-refuge theory in the past has traditionally only been applied to humans, but many of the same contingencies governing spatial preference ought to also hold true in animals. The focus of this study was to examine if this phenomena also occurs in animals.

Spatial cognition in the gerbil: computing optimal escape routes from visual threats.

Previous studies in our laboratory have shown that when presented with a sudden stimulus simulating an oncoming predator, Mongolian gerbils can compute the optimal trajectory to a safe refuge, taking into account the position of the threat, the location of a clearly visible refuge, and several other contextual variables as well. In the present studies, the main goal was to explore the abilities of gerbils to use mental representations of spaces that were visually occluded by opaque barriers to compute efficient escape trajectories. In all studies, gerbils were placed into a round open field containing a single refuge.

Plasticity of the association between visual space and action space in a blind-walking task.

Many experiments have shown that a brief visual preview provides sufficient information to complete certain kinds of movements (reaching, grasping, and walking) with high precision. This suggests that participants must possess a calibration between visual target location and the kinaesthetic, proprioceptive, and/or vestibular stimulation generated during movement towards the target. We investigated the properties of this calibration using a cue-conflict paradigm in which participants were trained with mismatched locomotor and visual input.

Short-term memory impairment and reduced hippocampal c-Fos expression in an animal model of fetal alcohol syndrome.

Background: Previous work in our laboratory has shown that exposure to ethanol during the brain growth spurt impairs spatial short-term memory in rats on the delayed matching-to-place (DMP) version of the Morris water maze. The objectives of this study were to ascertain whether this impairment could: 1) be prevented by increasing the length of encoding time and 2) be related to hippocampal c-Fos expression.

Methods: Using an artificial rearing model, male Long-Evans rats were fed 6.

The contributions of static visual cues, nonvisual cues, and optic flow in distance estimation.

By systematically varying cue availability in the stimulus and response phases of a series of same-modality and cross-modality distance matching tasks, we examined the contributions of static visual information, idiothetic information, and optic flow information. The experiment was conducted in a large-scale, open, outdoor environment. Subjects were presented with information about a distance and were then required to turn 180 before producing a distance estimate.

Visually guided locomotion in the gerbil: a comparison of open- and closed-loop control.

Two experiments were conducted in order to explore the effects of visual feedback on control of locomotion in the gerbil. In the first experiment, gerbils were trained to run down an alleyway towards a visual target in order to obtain food reward. One group of animals was trained to run to a target whose size never varied while another group was trained to run to a target whose size varied randomly from trial to trial.

A comparison of visual and nonvisual sensory inputs to walked distance in a blind-walking task.

Two experiments were conducted in order to assess the contribution of locomotor information to estimates of egocentric distance in a walking task. In the first experiment, participants were either shown, or led blind to, a target located at a distance ranging from 4 to 10 m and were then asked to indicate the distance to the target by walking to the location previously occupied by the target. Participants in both the visual and locomotor conditions were very accurate in this task and there was no significant difference between conditions.