Eligibility Criteria:
* INCLUSION CRITERIA:
Healthy male and female volunteers who have no present or past diagnosis of neurologic, medical or psychiatric conditions which may confound either learning trails, normal sleep patterns or the ability to undergo sleep deprivation.
Healthy male and female subjects, 18-28 years of age, who do not meet any exclusion criteria, with self-reported normal sleep patterns (i.e., 6-9 h per night) and no major sleep disruptions during the four weeks prior to evaluation will be considered for inclusion in the study.
EXCLUSION CRITERIA INCLUDE A HISTORY OF, OR CURRENT:
1. chronic medical condition which is a contraindication for PET or MRI scanning,
2. past or present diagnosis of psychiatric conditions (DSM-IV criteria) (many conditions (e.g. depression), may confound performance on learning trails or be associated with baseline sleep abnormalities),
3. chronic/degenerative/acquired neurologic disorder, (4) family history of genetically transmissible neurologic disorder,
(5) sleep disorders or medical conditions associated with chronically disordered sleep which may confound performance on learning trails or interfere with the sleep requirements of this study,
(6) visual impairments which may confound performance on learning trails,
(7) claustrophobic subjects,
(8) subjects who meet the above inclusion criteria, but are unable to cooperate with the requirements of the study (e.g. refusal to wear actigraphs or maintain 10 hours time in bed, reported difficulty sleeping away from home or on their backs).
(9) Subjects with chronic indicated or non-indicated use of any medications which interfere with sleep architecture and/or learning trails will be excluded. Generally, we will prohibit the use of medications/agents (e.g. anti-histamines, benadryl, melatonin, cigarettes, chocolate, coffee, tea, caffeine drinks etc.), which have significant CNS penetration, are alerting, and/or disrupt physiologic sleep-wake cycles or sleep architecture, for the 72 hrs immediately preceding presentation for the study. To acclimatize subjects, we will encourage patients to discontinue or minimize the use of these agents/medications (e.g. less than or equal to 1 cup of coffee/day) at the time of initial screening (at the same time as actigraphy application, approximately 2 wks prior to the study).
Similarly, we ask subjects to minimize alcohol use for the 2 wks prior to the study and will discontinue alcohol use for the 72 hrs immediately preceding the study.
(10) Subjects who have used illicit drugs (marijuana, cocaine, heroin, etc.) within the immediate 2 wks preceding the study.
(11) Female subjects will be excluded if either clinical history is suspicious for, or laboratory evaluation is consistent with pregnancy.
(12) Subjects unwilling to undergo HIV testing, unless enrolling in Part IIa of the study.
(13) Subjects who test HIV positive.
(14) Patients with para- and/or ferro-magnetic prosthesis/implants/fragments in their body will be excluded from the study.