Effects of Sleep Deprivation and Recovery on Cognitive Functions
Condition: Sleep Deprivation
MeSH terms: Sleep Deprivation
Study type: Observational

Summary: 
      This study will measure brain activity in individuals performing language tasks while in
      various states of alertness to learn more about how the central nervous system is affected by
      impairments such as sleepiness.

      Healthy normal volunteers between 20 and 40 years of age may be eligible for this study.
      Candidates must be non-smokers, right-handed, speak English fluently and have at least 12
      years of education. They are screened with a medical history, physical examination, hearing
      and speech evaluation, computer task training, blood and urine tests and a late-night
      functional magnetic resonance imaging (fMRI) scan (see description below). Before screening
      and again before participating in the study, candidates wear an actigraph (a wristwatch-like
      device that records motion) for 7 days to provide a measure of their sleep-wake patterns.

      Participants undergo the following tests and procedures:

        -  Extended wakefulness: Subjects are kept awake longer than is normal for them in their
           everyday life to be able to examine the brain under conditions of sleepiness. They are
           engaged in activities with the research staff during this waking time.

        -  Functional magnetic resonance imaging: Subjects undergo five separate fMRI scans-one
           during screening and four others during the main part of the study. fMRI uses a magnetic
           field and radio waves to produce images of the brain. The subject lies on a table that
           is moved into the scanner (a narrow cylinder), wearing earplugs to muffle loud knocking
           and thumping sounds that occur during the scanning process. Brain scans are taken at
           rest and while the subject performs tasks, which include pressing a button upon seeing
           certain shapes and performing various language tasks, such as saying memorized or new
           words, listening to narratives, and describing everyday procedures.

        -  Neurological, speech-language, and neuropsychological testing: Before the fMRI exams and
           during the period of extended wakefulness, subjects complete a series of tests that
           measure speech, language, memory and visual skills. Portions of the tests may be video-
           or autiotaped.

        -  Interviews and questionnaires: Participants are interviewed about their handedness,
           sleep history, and presence of medical or neurological symptoms.

        -  Electrophysiological studies: Subjects have an electroencephalograph (EEG) to measure
           the electrical activity of the brain and surface electromyography (EMG) to measure
           movements of muscles involved in moving and speaking. For the EEG, electrodes (small
           metal disks) are attached to the surface of the scalp or to a cap placed over the head.
           For the EMG, electrodes are attached to the skin of the face and neck by plastic or
           paper tape.
    

Detailed description: 
      Objectives of this protocol are to examine fMRI data taken concurrently with speech,
      language, and decision making tasks under conditions of both alertness and sleep deprivation,
      comparing fMRI-defined neural activation across states and behavioral performance, assessing
      changes in brain function with sleep deprivation. An additional objective is to develop an
      fMRI signal based sleep scoring system. Subjects will be 45 normal healthy volunteers, age
      20-40, who meet criteria both for safe participation in an fMRI environment and for
      suitability for research on normal human sleep. To examine speech and language processing and
      also to examine depth of sleep, we will use a within-subjects free behavior design in which
      we search for patterns in the arterial spin labeled (ASL) or the blood oxygen dependent
      (BOLD) signal in fMRI data recorded while subjects say rehearsed word sets, describe or
      listen to novel procedures, or transition from wake to sleep. To gauge subjects' speech and
      language, we will record, concurrently with fMRI, their voice for analysis in conditions of
      both alertness and sleep deprivation. To examine decision making, we will compare the fMRI
      signal during response execution and inhibition across conditions of alertness and sleep
      deprivation. To gauge subjects' depth of sleep during fMRI, we will use both physiological
      (e.g., EEG) and behavioral measures (e.g., latency and quality of rehearsed verbal response
      to external stimuli presented during sleep). For speech, language processing, and depth of
      sleep, key measures will include fundamental frequency, speaking rate, voice onset, word
      production, and linguistic variables (phonological, syntactic, and pragmatic) derived from
      recorded transcripts. For decision making, the key measure will be subjects' errors and
      latencies in responding to cues to make or refrain from making a prescribed action. The fMRI
      data corresponding to these behavioral data are expected to show systematic changes in neural
      activation patterns that parallel behavioral changes with sleep deprivation.
    

Keywords: Sleep Architecture; Sleep Measures; Speech Articulation; Cerebral Perfusion; Neuroimaging; Healthy Volunteer; HV