Journal of neurophysiology
October 1, 2021
Christopher B O'Brien, Clarence E Locklear, Zachary T Glovak et al.
18 citations
Antinociceptive doses of fentanyl, morphine, and buprenorphine significantly and differentially disrupt EEG-defined states of consciousness in adult male C57BL/6J mice. Compared with saline, fentanyl and morphine decreased NREM sleep, morphine eliminated REM sleep, and buprenorphine eliminated both NREM and REM sleep. The opioids altered specific EEG frequency bands and caused dissociated states of consciousness, disrupting the temporal organization of sleep/wake states. These findings are relevant because buprenorphine is used in medication-assisted therapy for opioid addiction, and disordered sleep can promote addiction relapse.
Journal of neurophysiology
October 1, 2022
Don M Tucker, Phan Luu, Mark Johnson
16 citations
Conscious experience is intricately linked to neurophysiological mechanisms of memory. A study involving 100 participants revealed that implicit memory, regulated by lemnothalamic pathways during REM sleep, underpins unconscious awareness, while explicit memory, driven by collothalamic structures during NREM sleep, shapes focused consciousness. This dual system highlights how ongoing cognitive processes are influenced by a hierarchy of neural connections across various brain regions. Understanding these mechanisms may shed light on the enigmatic qualities of subjective experiences, often referred to as "the hard problem of consciousness."
Journal of neurophysiology
April 1, 2026
Yoshihiro Iwamura, Kantaro Nishigori, Masataka Yamaguchi et al.
At a dose matching the concentration found effective for depression in humans, the anesthetic (R,S)-ketamine increased gamma power in the EEG of rhesus macaques, replicating clinical findings. The enantiomer (R)-ketamine produced a similar rise in gamma power but had weaker effects on EEG features linked to side effects. Ketamine metabolites caused only mild EEG changes, suggesting they contribute little to ketamine's EEG effects. The results indicate (R)-ketamine may have a broader therapeutic range and lower risk of adverse effects than (R,S)-ketamine.
Journal of neurophysiology
July 14, 2025
Alexander Schielke, Bart Krekelberg
Coordinated neural activity is impaired in neuropsychiatric disorders. Steady-state visual evoked potentials (SSVEPs), large-scale rhythmic brain responses to flickering light, are reduced in people with schizophrenia. Hypofunction of the N-methyl d-aspartate receptor (NMDAR) may contribute to schizophrenia symptoms. In nonhuman primates with permanent electrode arrays in primary visual cortex, a subanesthetic dose of ketamine (an NMDAR antagonist) induced NMDAR hypofunction and substantially reduced SSVEPs across frequencies from 5 to 40 Hz, mirroring findings in schizophrenia. These results suggest NMDAR hypofunction can account for altered coordinated activity and support its role in schizophrenia symptoms.
Journal of neurophysiology
April 1, 2025
Tobias Teichert, László Papp, Ferenc Vincze et al.
A new imaging method called MePhys (mesoscopic electrophysiology) records local field potentials from 992 electrode contacts distributed across 62 shafts implanted throughout a monkey hemisphere, enabling simultaneous measurement of over 300,000 electrode pairs. This technique combines millisecond temporal resolution with millimeter spatial resolution across a large field of view. Administering a subanesthetic dose of ketamine, which can mimic aspects of psychosis, induced a pronounced state of functional disconnection and prevented the formation of stable large-scale intrinsic brain states. MePhys offers a complementary window into brain function that bridges the gaps between fMRI, EEG, and microscopic electrophysiology.
Journal of neurophysiology
April 1, 2026
Inga Griškova-bulanova, Čestmír Vejmola, Tomáš Páleníček
Psilocin, the active metabolite of psilocybin, selectively disrupts auditory neural synchronization in rats in a frequency- and region-specific manner. In eight adult male Wistar rats implanted with cortical electrodes, psilocin (4 mg/kg) reduced phase-locking at 40 Hz stimulation in the right temporal cortex, with no significant changes in frontal or left temporal regions or at 80 Hz stimulation. Spectral power was globally reduced at 80 Hz after psilocin, but not consistently at 40 Hz. These results indicate that low-gamma oscillations are sensitive to serotonergic modulation via 5-HT2A receptor signaling, supporting auditory steady-state responses as translational biomarkers for altered perceptual states.
Journal of neurophysiology
May 1, 2025
Petra Valtonen, Stanislav Rozov, Iina Annala et al.
Short-term administration of nitrous oxide (N2O) increases power in the theta frequency range (4-7 Hz) of the electroencephalogram (EEG) after the gas is withdrawn, but does not affect delta frequency (0.5-4 Hz) power. In a study of 14 healthy male participants, those receiving 50% N2O either continuously for 20 minutes or in two 10-minute inhalations showed rapid EEG transitions during gas administration and withdrawal. Power in high-frequency gamma bands increased during N2O, while beta and alpha frequencies decreased. After withdrawal, theta power increased in several electrodes, with negligible differences between the two treatment groups. The effect was reproducible with repeated dosing.
Journal of neurophysiology
September 1, 2023
Ludovic Molle, Alexandre Coste, Charles-Etienne Benoit et al.
Inhalation, compared with exhalation, improves perceptual awareness and speeds up objective decision-making without impairing accuracy. The breathing phase modulates attention, with exhalation linked to reduced awareness and slower decisions. The study recorded the breathing rhythms of 30 humans performing a near-threshold decision-making task involving a liminal Gabor stimulus. The findings suggest that breathing shapes the emergence of subjective experience and decision-making, building on questions about the physiological mechanisms underlying consciousness.