Visual imagery is the invention or recreation of a perceptual experience in the absence of retinal input.The degree to which the same neural representations are involved in both visual imagery and visual perception is unclear. Previous studies have shown that visual imagery interferes with perception (Perky effect). We report here psychophysical data showing a direct facilitatory effect of visu...

In order to survive and develop effectively in an increasingly dynamic and uncertain environment, an organization should have the capacity for continuous and adaptive changes. Change can only occur through the collaboration of participants of this process. Collaboration should be adaptive. Adaptability of collaboration is expressed by its adjustment to dynamic organizational changes. Adaptive c...

BACKGROUND AND PURPOSE Botulinum toxin is increasingly used to treat upper limb spasticity due to stroke, but its impact on arm function is unclear. We evaluated botulinum toxin for upper limb spasticity and function poststroke. METHODS Three hundred thirty-three patients with stroke with upper limb spasticity and reduced arm function participated in a multicenter randomized controlled trial....

Learning is often understood as an organism's gradual acquisition of the association between a given sensory stimulus and the correct motor response. Mathematically, this corresponds to regressing a mapping between the set of observations and the set of actions. Recently, however, it has been shown both in cognitive and motor neuroscience that humans are not only able to learn particular stimul...

The purpose of this study was to investigate whether the gating of interlimb cutaneous reflexes is altered by holding an earth-referenced handrail during locomotion. In the first experiment, subjects performed locomotor tasks of varying difficulty (level walking, incline walking, and stair climbing) while lightly holding an earth-referenced rail. In the second experiment, the extent of rail con...

Motor responses evoked by transcranial magnetic stimulation OMS) or transcranial electrical stimulation (TCS) can be facilitated by a prior conditioning stimulus to an afferent nerve. Two facilitation periods are described short (SI), when the nerve stimulus is given near 0 to 10 ms after cranial stimulation, and long (LI), when nerve stimulation is given 25-60 ms before the cranial stimula...

Prior learning of a motor skill creates motor memories that can facilitate or interfere with learning of new, but related, motor skills. One hypothesis of motor learning posits that for a sensorimotor task with redundant degrees of freedom, the nervous system learns the geometric structure of the task and improves performance by selectively operating within that task space. We tested this hypot...

INTRODUCTION Motor commands to perform exercise tasks may also induce activation of cardiovascular centres to supply the energy needs of the contracting muscles. Mental stressors per se may also influence cardiovascular homeostasis. We investigated the cardiovascular response of trained runners simultaneously engaged in mental and physical tasks to establish if aerobically trained subjects coul...

In an earlier paper, we reported task-specific impairments and improvements caused by applying TMS over cortical visual area V5 [Proceedings of the Royal Society of London B 265 (1998) 537]. The phenomenon is further investigated in the present study using two of the previous tasks: a motion/form conjunction in which TMS impaired performance and a colour/form conjunction in which performance wa...