Progress in brain research
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The natural history of recovery from brain injury typically consists of a period of impaired consciousness, a subsequent period of confusion and amnesia, followed by a period of post-confusional recovery of function. Patients with more severe injuries may have more prolonged episodes of unconsciousness or minimal consciousness and may not fully evolve through this continuum of recovery. There is limited information on the course of recovery and long-term outcome of patients with prolonged unconsciousness, particularly those with extended periods in the minimally conscious state. Further, patients with impaired consciousness are frequently denied access to hospital-based rehabilitation services because of uncertain prognosis and a perceived lack of benefit from rehabilitative interventions. ⋯ Patients in VS whose transition to MCS occurred within 8 weeks of onset are likely to continue recovering to higher levels of functioning, a substantial proportion to household independence, and productive pursuits. Patients with TBI are more likely to progress than patients with nonTBI, though significant improvement in the nonTBI group is still possible. Active, higher intensity, rehabilitation should be strongly considered for patients with severely impaired consciousness after brain injury, especially for patients with TBI who have signs of progression to the MCS.
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Review
The use of repetitive transcranial magnetic stimulation (rTMS) for the treatment of spasticity.
Spasticity is a common disorder in patients with injury of the brain and spinal cord, especially in patients affected by multiple sclerosis (MS). In MS, spasticity is a major cause of long-term disability, it significantly impacts daily activities and quality of life and is only partially influenced by traditional spasmolytic drugs. ⋯ The H reflex is a reliable electrophysiologic measure of the stretch reflex, and has been used in previous studies to test the effects of rTMS of the motor cortex on spinal circuitry. Based on these premises, originating from physiological studies in normal subjects, some studies have demonstrated that rTMS of the leg motor cortex can be beneficial in the management of spasticity by enhancing corticospinal tract excitability and reducing H reflex amplitude.
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Why do complex-partial seizures in temporal lobe epilepsy (TLE) cause a loss of consciousness? Abnormal function of the medial temporal lobe is expected to cause memory loss, but it is unclear why profoundly impaired consciousness is so common in temporal lobe seizures. Recent exciting advances in behavioral, electrophysiological, and neuroimaging techniques spanning both human patients and animal models may allow new insights into this old question. While behavioral automatisms are often associated with diminished consciousness during temporal lobe seizures, impaired consciousness without ictal motor activity has also been described. ⋯ Supporting this hypothesis, recent rat studies during partial limbic seizures have shown that behavioral arrest is associated with frontal cortical slow waves, decreased neuronal firing, and hypometabolism. Animal studies further demonstrate that cortical deactivation and behavioral changes depend on seizure spread to subcortical structures including the lateral septum. Understanding the contributions of network inhibition to impaired consciousness in TLE is an important goal, as recurrent limbic seizures often result in cortical dysfunction during and between epileptic events that adversely affects patients' quality of life.
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Disorders of consciousness (DOC) raise profound scientific, clinical, ethical, and philosophical issues. Growing knowledge on fundamental principles of brain organization in healthy individuals offers new opportunities for a better understanding of residual brain function in DOCs. We here discuss new perspectives derived from a recently proposed scheme of brain organization underlying consciousness in healthy individuals. ⋯ A state where both extrinsic and intrinsic systems are hypofunctional is predicted to lead to markedly impaired consciousness as seen in DOCs. Finally, we review the potential use of ultra-slow fluctuations in BOLD signal as a tool for assessing the functional integrity of extrinsic and intrinsic systems during "resting state" fMRI acquisitions. In particular, we discuss the potential provided by assessment of these slow spontaneous BOLD fluctuations as a novel tool in assessing the cognitive state and chances of recovery from brain pathologies underlying DOCs.
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Perceptual decision making is the process by which information gathered from sensory systems is combined and used to influence our behavior. Importantly, however, the route from perception to action is not a one-way street, rather, perception and action interact continuously. ⋯ We conclude that there is evidence for the liaison of action and perception in simple decision-making tasks. This framework may also be extended to reward-based decision making in humans.