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
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.