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From proof of principle to clinical application
SCIENCE AND MEDICINE
“Sleep on it”, say scientists rain regions that are activated when a person learns a new task are reactivated during sleep, suggesting a relationship between sleep and memory processing, says Pierre Maquet (Institute of Neurology, University College London, UK). Maquet and colleagues used positron emission tomography (PET) and regional cerebral blood flow measurements to assess brain activity during the learning of a new task and during rapid eye movement (REM) sleep. Study participants were trained to press buttons in response to symbols appearing on a screen; they became faster with practice, and faster still after a night’s sleep. Similar patterns of brain activity—most notably, activation of the cuneus and adjacent striate cortex, left premotor cortex, and mesencephalon—were seen in trained individuals when they per-
formed the task awake, and during REM sleep. By contrast, those who were not trained in the task had significantly less activation in these
Rights were not granted to include this image in electronic media. Please refer to the printed journal.
To sleep, perchance to learn
brain areas during REM sleep (Nat Neurosci 2000; 3: 831–36). The findings “provide some cerebral correlates to previous behavioural observations” suggesting that memory consolidation might occur during sleep, says Maquet. “To get subjects to sleep consistently while in the PET scanner is
Science Photo Library
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quite remarkable, [and this has led to] an exciting step forward in understanding the functions of sleep”, comments Charles George of the University of Western Ontario, Canada. But while the data point to an important role for REM sleep in the creation of new memory from information processing, they also raise questions, he notes. For example, are there differences in brain activity compared with wakefulness for slow wave sleep, as for REM sleep? Is the first REM period more or less important in memory processing than the second or third? Will drugs that typically alter REM sleep, such as antidepressants, influence acquisition of new memory, asks George. Such questions are the stuff that dreams (and subsequent studies) are made of. Marilynn Larkin
Spinal cord recovery moves one step closer elegates at the International Society for Autonomic Neuroscience Millenium Congress (London, UK; July 17–21) heard a series of talks on the recovery of autonomic nervous system function after spinal injury. Of particular interest to the audience of autonomic neuroscientists and clinicians was a presentation given by a researcher studing the somatic nervous system. Geoffrey Raisman (National Institute for Medical Research, London, UK) showed that functional repair of corticospinal axons was possible in rats by transplantating olfactory ensheathing cells into the lesion. Since neurosensory cells of the adult olfactory system are continuously replaced, this means that new neurosensory cell axons must grow continuously into the brain. Their entry point is provided by a special type of glial cell, the olfactory ensheathing cell. Raisman’s team hypothesised that injection of these special olfactory ensheathing cells into a region of damage in the corticospinal tract (CST) might also be able to provide a pathway for CST axons to regenerate. The researchers made unilateral lesions in the upper cervical corticospinal tract of rats, and used behavioural tests to determine whether function had returned after transplantation of the olfactory cells.
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THE LANCET • Vol 356 • July 29, 2000
Raisman showed a video that clearly demonstrated that rats who had received the transplant recovered the ability to perform a directed pawreaching task. In untreated animals this function did not return. “I can count on the fingers of one hand the number of researchers who have been able to show functional regeneration”, says Lawrence Schramm (John Hopkins University School of Medicine, Baltimore, MD, USA), who was so impressed with Raisman’s data that he arranged an impromtu visit of his lab and is now hoping to
collaborate with him. For Schramm, who is an autonomic neurophysiologist, of special interest is the potential of this technique for treating the autonomic effects of a spinal-cord injury. After all, he explains, although paralysis of the lower limbs is a tragic consequence of many road traffic accidents, it is autonomic dysfunctions, such as kidney infections or sudden episodes of hypertension, that can potentially prove fatal to a patient. James Butcher
From proof of principle to clinical application A transplantation-based therapy for CNS diseases such as multiple sclerosis moves one step closer this week with the publication of a paper by Sue Barnett (University of Glasgow, UK), Robin Franklin (University of Cambridge, UK) and colleagues which shows that human olfactory ensheathing cells (OECs) can be isolated and grown in culture (Brain 2000; 123: 1581–88). These cells have been shown to remyelinate damaged axons in rats, but it was uncertain whether it would be possible to identify OECs in human beings, whose olfactory system is less well developed than that in rodents. “This study represents a significant advance for those considering olfactory glia as a potential cell type to use in clinical trials aimed at enhancing regeneration of axons following spinal cord trauma”, according to William Blakemore (Cambridge University, Cambridge, UK) . Blakemore also points out that making the transition between the proof of principle established using rodents to the use of the approach in man is not automatic: “[This paper] demonstrates once again that the cultivation and expansion of human cells is not as straightforward as expansion of their rodent counterparts. [Barnett’s] observations indicate that new reagents and techniques have to be developed by those who need to work with human cells”. James Butcher
405
For personal use only. Not to be reproduced without permission of The Lancet.
“Sleep on it”, say scientists rain regions that are activated when a person learns a new task are reactivated during sleep, suggesting a relationship between sleep and memory processing, says Pierre Maquet (Institute of Neurology, University College London, UK). Maquet and colleagues used positron emission tomography (PET) and regional cerebral blood flow measurements to assess brain activity during the learning of a new task and during rapid eye movement (REM) sleep. Study participants were trained to press buttons in response to symbols appearing on a screen; they became faster with practice, and faster still after a night’s sleep. Similar patterns of brain activity—most notably, activation of the cuneus and adjacent striate cortex, left premotor cortex, and mesencephalon—were seen in trained individuals when they per-
formed the task awake, and during REM sleep. By contrast, those who were not trained in the task had significantly less activation in these
Rights were not granted to include this image in electronic media. Please refer to the printed journal.
To sleep, perchance to learn
brain areas during REM sleep (Nat Neurosci 2000; 3: 831–36). The findings “provide some cerebral correlates to previous behavioural observations” suggesting that memory consolidation might occur during sleep, says Maquet. “To get subjects to sleep consistently while in the PET scanner is
Science Photo Library
B
quite remarkable, [and this has led to] an exciting step forward in understanding the functions of sleep”, comments Charles George of the University of Western Ontario, Canada. But while the data point to an important role for REM sleep in the creation of new memory from information processing, they also raise questions, he notes. For example, are there differences in brain activity compared with wakefulness for slow wave sleep, as for REM sleep? Is the first REM period more or less important in memory processing than the second or third? Will drugs that typically alter REM sleep, such as antidepressants, influence acquisition of new memory, asks George. Such questions are the stuff that dreams (and subsequent studies) are made of. Marilynn Larkin
Spinal cord recovery moves one step closer elegates at the International Society for Autonomic Neuroscience Millenium Congress (London, UK; July 17–21) heard a series of talks on the recovery of autonomic nervous system function after spinal injury. Of particular interest to the audience of autonomic neuroscientists and clinicians was a presentation given by a researcher studing the somatic nervous system. Geoffrey Raisman (National Institute for Medical Research, London, UK) showed that functional repair of corticospinal axons was possible in rats by transplantating olfactory ensheathing cells into the lesion. Since neurosensory cells of the adult olfactory system are continuously replaced, this means that new neurosensory cell axons must grow continuously into the brain. Their entry point is provided by a special type of glial cell, the olfactory ensheathing cell. Raisman’s team hypothesised that injection of these special olfactory ensheathing cells into a region of damage in the corticospinal tract (CST) might also be able to provide a pathway for CST axons to regenerate. The researchers made unilateral lesions in the upper cervical corticospinal tract of rats, and used behavioural tests to determine whether function had returned after transplantation of the olfactory cells.
D
THE LANCET • Vol 356 • July 29, 2000
Raisman showed a video that clearly demonstrated that rats who had received the transplant recovered the ability to perform a directed pawreaching task. In untreated animals this function did not return. “I can count on the fingers of one hand the number of researchers who have been able to show functional regeneration”, says Lawrence Schramm (John Hopkins University School of Medicine, Baltimore, MD, USA), who was so impressed with Raisman’s data that he arranged an impromtu visit of his lab and is now hoping to
collaborate with him. For Schramm, who is an autonomic neurophysiologist, of special interest is the potential of this technique for treating the autonomic effects of a spinal-cord injury. After all, he explains, although paralysis of the lower limbs is a tragic consequence of many road traffic accidents, it is autonomic dysfunctions, such as kidney infections or sudden episodes of hypertension, that can potentially prove fatal to a patient. James Butcher
From proof of principle to clinical application A transplantation-based therapy for CNS diseases such as multiple sclerosis moves one step closer this week with the publication of a paper by Sue Barnett (University of Glasgow, UK), Robin Franklin (University of Cambridge, UK) and colleagues which shows that human olfactory ensheathing cells (OECs) can be isolated and grown in culture (Brain 2000; 123: 1581–88). These cells have been shown to remyelinate damaged axons in rats, but it was uncertain whether it would be possible to identify OECs in human beings, whose olfactory system is less well developed than that in rodents. “This study represents a significant advance for those considering olfactory glia as a potential cell type to use in clinical trials aimed at enhancing regeneration of axons following spinal cord trauma”, according to William Blakemore (Cambridge University, Cambridge, UK) . Blakemore also points out that making the transition between the proof of principle established using rodents to the use of the approach in man is not automatic: “[This paper] demonstrates once again that the cultivation and expansion of human cells is not as straightforward as expansion of their rodent counterparts. [Barnett’s] observations indicate that new reagents and techniques have to be developed by those who need to work with human cells”. James Butcher
405
For personal use only. Not to be reproduced without permission of The Lancet.