Regional Rates of Cerebral Protein Synthesis: Effects of Sleep and Memory Consolidation
Condition: Brain Mapping
Study type: Observational

Summary: 
      Background:

        -  The brain needs sleep to function normally, but the purpose of sleep is not understood.
           Brain activity decreases during sleep, so it may be that sleep is important to maintain,
           repair, or reorganize brain cells. In animals, the formation of brain proteins increases
           during sleep, and the same thing may happen in humans.

        -  There is also evidence that learning and memory are helped by sleep, and that the
           synthesis of proteins in the brain are involved.

      Objectives:

        -  To examine the formation of proteins in the brain while people are awake, deprived of
           sleep, and during sleep.

        -  To look at the formation of proteins in the brain while awake or asleep and following
           learning a task.

      Eligibility:

        -  Healthy volunteers between 18 and 28 years of age.

        -  Volunteers must not have psychiatric, neurologic, or sleep disorders or certain types of
           vision problems, and must be able to undergo imaging studies.

      Design:

        -  Study Part I (protein formation in waking, sleep deprivation, and sleep):

        -  Participants will wear an actigraph (a unit to record motor activity) for 2 weeks prior
           to admission.

        -  Participants will have physical and psychological examinations, along with a blood
           sample.

        -  After admission participants will have three positron emission tomography (PET) scans to
           study protein formation and one magnetic resonance imaging (MRI) scan over the course of
           two days.

        -  Participants may be asked to stay awake for as long as 20 hours and will be monitored
           throughout.

        -  Participants will be able to sleep overnight after they complete the required scans and
           monitoring, and will be discharged the following morning.

        -  Study Part II (protein formation in waking and sleep combined with a learning task):

        -  Participants will wear an actigraph (a unit to record motor activity) for 2 weeks prior
           to admission.

        -  Participants will have physical and psychological examinations, along with a blood
           sample.

        -  After admission participants may be asked to stay awake for as long as 20 hours and will
           be monitored throughout.

        -  The next morning, participants will be trained to perform a computerized visual
           discrimination task, and will be tested 8 hours later (after sleep or after remaining
           awake) on the visual discrimination task.

        -  Some participants may have PET and MRI scans as part of the study.

        -  Participants will be able to sleep overnight after they complete the required tests and
           scans, and will be discharged the following morning.

        -  Participants will receive financial compensation for their participation in these
           studies.
    

Detailed description: 
      The importance of sleep is widely appreciated, but the actual function of sleep remains
      unknown. Sleep occurs in much of the animal kingdom, in all mammals and birds and even in
      some lower forms. Sleep deprivation impairs brain function, and in rats, total sleep
      deprivation for 2-3 weeks results in death. One hypothesized role of sleep is for restoration
      and reorganization of neuronal circuits. There is some indirect evidence that during sleep,
      when cerebral energy requirements are reduced, cell resources are diverted to protein
      synthesis for the restoration of structure and function. The objectives of the present study
      are: 1) to further define the relationship between regional rates of cerebral protein
      synthesis (rCPS) and sleep and 2) to ascertain whether sleep-dependent visual learning during
      slow wave sleep (SWS) results in increases in rCPS in the primary visual cortex. We propose
      to use a novel positron emission tomography (PET)-based technique to quantify regional rates
      of cerebral protein synthesis (rCPS) in young, adult, healthy volunteers. The first objective
      will be addressed in Part I in which we will study each subject under the following three
      conditions: 1) awake and sleep-sated, 2) awake and sleep-deprived, and 3) during SWS after
      sleep-deprivation. Our aim is to complete fully successful studies in 15 subjects. The second
      objective will be addressed in Part II in which we will assess the relationship between rCPS
      and sleep-dependent visual learning on a retinotopically specific task. Each participant will
      serve as his own control by comparing the trained primary visual cortex hemisphere with the
      untrained hemisphere to which comparable visual information is presented but without
      learning. In Part II we will study two groups of subjects: 1) One group will be studied
      during SWS following the training session; 2) The second group will be studied at the same
      interval following the training session but awake. Subjects will be monitored with
      polysomnography to identify the stages of sleep. Our aim in part II is to complete fully
      successful studies in 15 subjects in each of the two groups. We anticipate that the results
      of Part I will identify changes in rCPS in specific brain regions which are characteristic of
      SWS and results of Part II may reveal relationships between rCPS and memory consolidation
      during SWS.
    

Observational model: Cohort
Time perspective: Prospective
Keywords: Sleep; 14C-Leucine; Cerebral Protein Synthesis; Memory; Positron Emission Tomography (PET); HV; Healthy Volunteer