Phasic REM Transiently Approaches Wakefulness in the Human Cortex-A Single-Pulse Electrical Stimulation Study.
Kiyohide Usami, Riki Matsumoto, Katsuya Kobayashi, Takefumi Hitomi, Masao Matsuhashi, Akihiro Shimotake, Takayuki Kikuchi, Kazumichi Yoshida, Takeharu Kunieda, Nobuhiro Mikuni, Susumu Miyamoto, Ryosuke Takahashi, Akio Ikeda
Sleep August 1, 2017 DOI: 10.1093/sleep/zsx077 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Sample size | 7 |
| Population | Patients with intractable partial epilepsy undergoing invasive presurgical evaluation |
| Intervention | Single-pulse electrical stimulation |
| Keywords | Ccep Rem sleep Phasic rem Single-pulse electrical stimulation |
| Key findings | Cortical excitability to exogenous input differs between phasic and tonic REM sleep, with phasic REM showing weaker suppression of high gamma activity and thus a shift toward wakefulness. |
Abstract
To investigate the changes in cortical neural responses induced by external inputs during phasic rapid eye movement (p-REM) sleep. Single-pulse electrical stimulation (SPES) was directly applied to the human cortex during REM sleep through subdural electrodes, in seven patients who underwent invasive presurgical evaluation for intractable partial epilepsy. SPES was applied to parts of the cortex through the subdural electrodes, and induced cortical responses were recorded from adjacent and remote cortical areas. Phase-locked corticocortical-evoked potentials (CCEPs) and nonphase-locked or induced CCEP-related high gamma activity (CCEP-HGA, 100-200 Hz), which are considered proxies for cortical connectivity and cortical excitability, respectively, were compared among wakefulness, p-REM (within ±2 seconds of significant bursts of REM), and tonic REM (t-REM) (periphasic REM) periods. During REM sleep, SPES elicited a transient increase in CCEP-HGA, followed by a subsequent decrease or suppression. The HGA suppression during both p-REM and t-REM was stronger than during wakefulness. However, its suppression during p-REM was weaker than during t-REM. On the other hand, the CCEP waveform did not show any significant difference between the two REM periods. Cortical excitability to exogenous input was different between p-REM and t-REM. The change of the cortical excitability in p-REM was directed toward wakefulness, which may produce incomplete short bursts of consciousness, leading to dreams.