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graviceptive bias

Laure Mathevon, Nicolas Leroux, Céline Piscicelli, Emmanuelle Clarac, Shenhao Dai, Patrice Davoine, Paul Krack, Dominic Perennou
OBJECTIVE: To take care of postural disorders is a major issue in Parkinson's disease (PD). We present a documented observation suggesting the existence of a biased representation of verticality in PD, resulting in a severe retropulsion and recurrent falls. A rehabilitation program aimed to modulate verticality perception dramatically improved the postural perception of the vertical, trunk posture and balance abilities, and reduced retropulsion as well as lastingly fall frequency. OBSERVATIONS: A 68 year-old patient with Parkinson's disease fall backward 3 times a day...
September 2016: Annals of Physical and Rehabilitation Medicine
A Drakul, C J Bockisch, A A Tarnutzer
The visual line bisection task (LBT) is sensitive to perceptual biases of visuospatial attention, showing slight leftward (for horizontal lines) and upward (for vertical lines) errors in healthy subjects. It may be solved in an egocentric or allocentric reference frame, and there is no obvious need for graviceptive input. However, for other visual line adjustments, such as the subjective visual vertical, otolith input is integrated. We hypothesized that graviceptive input is incorporated when performing the LBT and predicted reduced accuracy and precision when roll-tilted...
August 1, 2016: Journal of Neurophysiology
Carmen Krewer, Katrin Rieß, Jeannine Bergmann, Friedemann Müller, Klaus Jahn, Eberhard Koenig
Some stroke patients with hemiparesis exhibit a so-called pusher behaviour, i.e., they actively push away from the unaffected side and lean towards the hemiparetic side. This impairs their postural balance to such a degree that they are often unable to sit or stand. Pusher behaviour thus substantially hampers the rehabilitation of these patients. So far only a few case studies on treatment strategies have been performed. This study investigated the immediate after-effects of galvanic vestibular stimulation (GVS), machine-supported gait training with the Lokomat, and physiotherapy with visual feedback components (PT-vf)...
February 2013: Gait & Posture
Julien Barra, Adélaïde Marquer, Roxane Joassin, Céline Reymond, Liliane Metge, Valérie Chauvineau, Dominic Pérennou
Internal models serve sensory processing, sensorimotor integration and motor control. They could be a way to construct and update a sense of verticality, by combining vestibular and somatosensory graviception. We tested this hypothesis by investigating self-orientation relative to gravity in 39 normal subjects and in subjects with various somatosensory losses showing either a complete deafferentation of trunk and lower limbs (14 paraplegic patients after complete traumatic spinal cord injury) or a gradient in the degree of a hemibody sensory loss (23 hemiplegic patients after stroke)...
December 2010: Brain: a Journal of Neurology
A A Tarnutzer, C J Bockisch, D Straumann
Precision and accuracy of the subjective visual vertical (SVV) modulate in the roll plane. At large roll angles, systematic SVV errors are biased toward the subject's body-longitudinal axis and SVV precision is decreased. To explain this, SVV models typically implement a bias signal, or a prior, in a head-fixed reference frame and assume the sensory input to be optimally tuned along the head-longitudinal axis. We tested the pattern of SVV adjustments both in terms of accuracy and precision in experiments in which the head and the trunk reference frames were not aligned...
February 2010: Journal of Neurophysiology
D A Pérennou, G Mazibrada, V Chauvineau, R Greenwood, J Rothwell, M A Gresty, A M Bronstein
The relationships between perception of verticality by different sensory modalities, lateropulsion and pushing behaviour and lesion location were investigated in 86 patients with a first stroke. Participants sat restrained in a drum-like framework facing along the axis of rotation. They gave estimates of their subjective postural vertical by signalling the point of feeling upright during slow drum rotation which tilted them rightwards-leftwards. The subjective visual vertical was indicated by setting a line to upright on a computer screen...
September 2008: Brain: a Journal of Neurology
Dominic Alain Pérennou, Bernard Amblard, El Mostafa Laassel, Charles Benaim, Christian Hérisson, Jacques Pélissier
OBJECTIVE: To investigate whether pusher behavior (ie, a tendency among stroke patients with spatial deficits to actively push away from the nonparalyzed side and to resist any attempt to hold a more upright posture) affects only the trunk, for which gravitational feedback is given by somesthetic information, or the head as well, whose gravitational information is mainly given by the vestibular system (without vision). DESIGN: Description and measurement of clinical features...
April 2002: Archives of Physical Medicine and Rehabilitation
G Clément, S J Wood, C E Lathan, R J Peterka, M F Reschke
Spatial transformations of the vestibular-optokinetic system must account for changes in head position with respect to gravity in order to produce compensatory oculomotor responses. The purpose of this experiment was to study the influence of gravity on the vestibulo-ocular reflex (VOR) in darkness and on visual-vestibular interaction in the pitch plane in human subjects using two different comparisons: (1) Earth-horizontal axis (EHA) rotation about an upright versus a supine body orientation, and (2) Earth-horizontal versus Earth-vertical (EVA) rotation axes...
1999: Journal of Vestibular Research: Equilibrium & Orientation
H O Karnath, M Fetter, M Niemeier
Previous studies in neglect patients using rotation of the body around the roll-axis revealed neglect of visual stimuli not only in the egocentric, body-centered left but also in the environmental left. The latter has been taken as evidence for a gravity-based environment-centered component of neglect occurring independently of the subject's actual body orientation. However, by using visual stimuli in a normally lightened room, the studies confounded the gravitational upright with the visible upright of the surround...
November 1998: Journal of Cognitive Neuroscience
D A Pérennou, B Amblard, C Leblond, J Pélissier
This study was aimed at demonstrating the existence of a biased postural vertical in humans with a recent cerebral lesion. The postural vertical of patients and controls was analysed comparatively using a self-regulated balancing task, performed in sitting posture. Patients displayed a quite constant (19/22) contralesional tilt of the postural vertical (mean -2.6 degrees), varying with the severity of their spatial neglect and hemianaethesia. Eight of them showed a pathological contralesional bias (mean -5...
August 14, 1998: Neuroscience Letters
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