title: Sleep modulates cortical connectivity and excitability in humans: Direct evidence from neural activity induced by single-pulse electrical stimulation.
abstract: Sleep-induced changes in human brain connectivity/excitability and their physiologic basis remain unclear, especially in the frontal lobe. We investigated sleep-induced connectivity and excitability changes in 11 patients who underwent chronic implantation of subdural electrodes for epilepsy surgery. Single-pulse electrical stimuli were directly injected to a part of the cortices, and cortico-cortical evoked potentials (CCEPs) and CCEP-related high-gamma activities (HGA: 100-200 Hz) were recorded from adjacent and remote cortices as proxies of effective connectivity and induced neuronal activity, respectively. HGA power during the initial CCEP component (N1) correlated with the N1 size itself across all states investigated. The degree of cortical connectivity and excitability changed during sleep depending on sleep stage, approximately showing dichotomy of awake vs. non-rapid eye movement (REM) [NREM] sleep. On the other hand, REM sleep partly had properties of both awake and NREM sleep, placing itself in the intermediate state between them. Compared with the awake state, single-pulse stimulation especially during NREM sleep induced increased connectivity (N1 size) and neuronal excitability (HGA increase at N1), which was immediately followed by intense inhibition (HGA decrease). The HGA decrease was temporally followed by the N2 peak (the second CCEP component), and then by HGA re-increase during sleep across all lobes. This HGA rebound or re-increase of neuronal synchrony was largest in the frontal lobe compared with the other lobes. These properties of sleep-induced changes of the cortex may be related to unconsciousness during sleep and frequent nocturnal seizures in frontal lobe epilepsy.
authors: Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Kiyohide
authors: K
authors: Usami
authors: Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Riki
authors: R
authors: Matsumoto
authors: Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Katsuya
authors: K
authors: Kobayashi
authors: Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.|Department of Respiratory Care and Sleep Control Medicine, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Takefumi
authors: T
authors: Hitomi
authors: Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Akihiro
authors: A
authors: Shimotake
authors: Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Takayuki
authors: T
authors: Kikuchi
authors: Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Masao
authors: M
authors: Matsuhashi
authors: Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Takeharu
authors: T
authors: Kunieda
authors: Department of Neurosurgery, Sapporo Medical University School of Medicine, Sapporo, 060-8543, Japan.
authors: Nobuhiro
authors: N
authors: Mikuni
authors: Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Susumu
authors: S
authors: Miyamoto
authors: Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Hidenao
authors: H
authors: Fukuyama
authors: Department of Neurology, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Ryosuke
authors: R
authors: Takahashi
authors: Department of Epilepsy, Movement Disorders and Physiology, Kyoto University Graduate School of Medicine, Kyoto, 606-8507, Japan.
authors: Akio
authors: A
authors: Ikeda
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology* / Q000503:physiopathology; D063132:Connectome / Q000379:methods*; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods; D004567:Electrodes, Implanted; D004827:Epilepsy / Q000503:physiopathology; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D065818:Gamma Rhythm / Q000502:physiology*; D006801:Humans; D008297:Male; D012894:Sleep Stages / Q000502:physiology*; D055815:Young Adult
keywords: CCEP; consciousness; frontal lobe epilepsy; high-gamma activity; non-REM; sleep