Novel genetic findings in an extended family pedigree with sleepwalking.

BACKGROUND: Sleepwalking is a common and highly heritable sleep disorder. However, inheritance patterns of sleepwalking are poorly understood and there have been no prior reports of genes or chromosomal localization of genes responsible for this disorder. OBJECTIVE: To describe the inheritance pattern of sleepwalking in a 4-generation family and to identify the chromosomal location of a gene responsible for sleepwalking in this family. METHODS: Nine affected and 13 unaffected family members of a single large family were interviewed and DNA samples collected. Parametric linkage analysis was performed. RESULTS: Sleepwalking was inherited as an autosomal dominant disorder with reduced penetrance in this family. Genome-wide multipoint parametric linkage analysis for sleepwalking revealed a maximum logarithm of the odds score of 3.44 at chromosome 20q12-q13.12 between 55.6 and 61.4 cM. CONCLUSION: Sleepwalking may be transmitted as an autosomal dominant trait with reduced penetrance. Here we describe the first genetic locus for sleepwalking at chromosome 20q12-q13.12.

Active sleep and its role in the prevention of apoptosis in the developing brain.

The aim of this study is to identify a possible function of Active Sleep (AS), also known as Rapid Eye Movement Sleep (REM) in humans, as a protective state during early Central Nervous System (CNS) development. Previous research suggest pharmacological agents that inhibit high levels of neuronal activity in the CNS (e.g., benzodiazepines, ethanol, and anesthetics) precipitate massive CNS programmed cell death (PCD), in developing mammals. AS is characterized by high levels of CNS activity at levels comparable to waking. AS occupies up to 75% of the circadian cycle in developing mammals (rodents from postnatal days 1-14 days (p1-p14), and humans from prenatal month seven to postnatal year one). Many studies have implicated AS as having an active role in the normal development of the visual system and have documented myriad behavioral anomalies as a result of AS deprivation. Reduced adult brain mass has also been observed after AS deprivation in developing rats during this period, however, no study to date has documented this process as it occurs (i.e., the cellular mechanisms that result in behavioral anomalies or reduced adult brain mass). The purpose of this study is to begin documentation of this process by utilizing histological techniques that identify the PCD process, if it occurs, after acute and prolonged AS deprivation in rats from ages p7 to p14 (a time of active synaptogenesis). Our methodology includes utilization of the alpha2-adrenergic receptor agonist clonidine, to deprive rat pups of AS at ages varying from p7 to p14. Pilot data from our laboratory has shown that an acute exposure to clonidine significantly reduces time spent in AS. The animals that were AS deprived also showed a statistically significant decrease in brain mass and have stained positively for PCD. If our hypotheses are correct, this research will have major implications with regard to determining the function(s) of REM sleep.

Characterization of the mu rhythm during rapid eye movement sleep.

OBJECTIVE: The rolandic mu rhythm, a resting activity of somatosensory cortex, is a striking feature of the waking human electroencephalogram. This study will demonstrate that activity with identical features occurs during rapid eye movement (REM) sleep. METHODS: Eye and chin leads were added during prolonged closed circuit television (video) electroencephalographic (EEG) recording with scalp (12 patients) or subdural electrodes including 64 contract grids over the frontoparietal cortices (5 patients). Sleep staging was performed by reformatting into standard polysomnography montages (using two EEG channels, and eye and chin channels) and applying standard scoring criteria. The recordings were then reviewed using all EEG channels to assess rhythmic EEG activity by a reader blinded to the sleep staging. RESULTS: During scalp recordings, 7-10 Hz central rhythms were seen during wakefulness in 7 patients, with 6 of these also having similar rhythms during REM sleep. Similar activity was seen over somatosensory cortex during wakefulness and REM in all invasively recorded patients. This activity was blocked by contralateral body movement or contralateral somatosensory stimuli, even during REM sleep. It was absent in other sleep stages. CONCLUSIONS: This REM sleep activity recapitulates all the characteristics of the waking rolandic mu rhythm. This demonstrates functional similarity between the states of wakefulness and REM sleep.