Leif Johannsen

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Our aim was to examine how brain imaging in the initial phase of a stroke could predict both acute/subacute as well as chronic spatial neglect. We present the first voxel-wise longitudinal lesion-behaviour mapping study, examining acute/subacute as well as chronic performance in the same individuals. Acute brain imaging (acquired on average 6.2 days(More)
Stroke patients with "pusher syndrome" show severe misperception of their own upright body orientation although visualvestibular processing is almost intact. This dissociation argues for a second graviceptive system in humans for the perception of body orientation. Recent studies revealed that the posterior thalamus is an important part of this system. The(More)
OBJECTIVE It has been shown recently that neck muscle vibration in combination with an exploration training leads to lasting amelioration of spatial neglect. The present study evaluated whether vibration of the left posterior neck muscles alone has the potential to induce lasting reduction in spatial neglect. DESIGN A multiple baseline design was used to(More)
Sirs: A recent study of Saj and colleagues [16] investigated the perception of the subjective visual vertical (SVV) in a small group of 4 subacute stroke patients with pusher syndrome following the development of a right hemisphere lesion. Hemiparetic stroke patients with ‘‘pusher syndrome’’ show the peculiar behavior of using the nonaffected arm or leg to(More)
Sensory information about body sway is used to drive corrective muscle action to keep the body's centre of mass located over the base of support provided by the feet. Loss of vision, by closing the eyes, usually results in increased sway as indexed by fluctuations (i.e. standard deviation, s.d.) in the velocity of a marker at C7 on the neck, s.d. dC7.(More)
BACKGROUND Walking in time with a metronome is associated with improved spatiotemporal parameters in hemiparetic gait; however, the mechanism linking auditory and motor systems is poorly understood. OBJECTIVE Hemiparetic cadence control with metronome synchronization was examined to determine specific influences of metronome timing on treadmill walking.(More)
Light touch contact between the body and an environmental referent reduces fluctuations of center of pressure (CoP) in quiet standing although the contact forces are insufficient to provide significant forces to stabilize standing balance. Maintenance of upright standing posture (with light touch contact) may include both predictive and reactive components.(More)
Stroke patients with ‘pusher syndrome’ actively push away from the non-hemiparetic side leading to a loss of postural balance and falling towards the paralysed side. The behaviour is due to an altered perception of the body's orientation in relation to gravity. Here, we studied the prognosis of the disorder. Twelve pusher patients first investigated(More)
BACKGROUND Recent findings argue for a pathway in humans for sensing the orientation of gravity and controlling upright body posture, separate from the one for orientation perception of the visual world. Stroke patients with contraversive pushing were shown to experience their body as oriented upright when actually tilted about 20 degrees to the(More)