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  • April 29, 2016

    Subtle Chemical Changes in Brain Can Alter Sleep-Wake Cycle

    Sleepy Brain

    A study out today in the journal Science sheds new light on the biological mechanisms that control the sleep-wake cycle. Specifically, it shows that a simple shift in the balance of chemicals found in the fluid that bathes and surrounds brain cells can alter the state of consciousness of animals.

    The study, which focuses on a collection of ions that reside in the cerebral spinal fluid (CSF), found that not only do these changes play a key role in stimulating or dampening the activity of nerve cells, but they also appear to alter cell volume causing brain cells to shrink while we sleep, a process that facilitates the removal of waste.

    Understanding what drives arousal is essential to deciphering consciousness and the lack thereof during sleep, said Maiken Nedergaard, M.D., D.M.Sc., co-director of the University of Rochester Center for Translational Neuromedicine and lead author of the study. We found that the transition from wakefulness to sleep is accompanied by a marked and sustained change in the concentration of key extracellular ions and the volume of the extracellular space.

    The current scientific consensus is that the brain is woken up by a set of neurotransmitters – which include compounds such as acetylcholine, hypocretin, histamine, serotonin, noradrenaline, and dopamine – that originate from structures deep within the brain and the brain stem. This cocktail of chemical messengers serve to activate – or arouse – a set of neurons in the cerebral cortex and other parts of the brain responsible for memory, thinking, and learning, placing the brain in a state of wakefulness.

  • January 11, 2016

    Immune System Cells Key to Maintaining Blood-Brain Barrier

    New research shows that the cells responsible for protecting the brain from infection and inflammation are also responsible for repairing the system of defenses that separates the brain from the rest of the body. These findings have significant clinical implications because certain cardiovascular drugs could possibly impede the brain's ability to repair itself after a stroke or other injury.

    This study shows that the resident immune cells of the central nervous system play a critical and previously unappreciated role in maintaining the integrity of the blood-brain barrier, said Maiken Nedergaard, M.D., D.M.Sc., co-director of the Center for Translational Neuromedicine at the University of Rochester Medical Center (URMC) and lead author of the study. When this barrier is breached it must be rapidly repaired in order to maintain the health of the brain and aid in recovery after an injury – a process that could be impaired by drugs that are intended to prevent this damage in the first place.

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