BACKGROUND: Previous studies have demonstrated inconsistent neurophysiologic effects of ketamine, although discrepant findings might relate to differences in doses studied, brain regions analyzed, coadministration of other anesthetic medications, and resolution of the electroencephalograph. The objective of this study was to characterize the dose-dependent effects of ketamine on cortical oscillations and functional connectivity. METHODS: Ten healthy human volunteers were recruited for study participation. The data were recorded using a 128-channel electroencephalograph during baseline consciousness, subanesthetic dosing (0.5 mg/kg over 40 min), anesthetic dosing (1.5 mg/kg bolus), and recovery. No other sedative or anesthetic medications were administered. Spectrograms, topomaps, and functional connectivity (weighted and directed phase lag index) were computed and analyzed. RESULTS: Frontal theta bandwidth power increased most dramatically during ketamine anesthesia (mean power ± SD, 4.25 ± 1.90 dB) compared to the baseline (0.64 ± 0.28 dB), subanesthetic (0.60 ± 0.30 dB), and recovery (0.68 ± 0.41 dB) states; P < 0.001. Gamma power also increased during ketamine anesthesia. Weighted phase lag index demonstrated theta phase locking within anterior regions (0.2349 ± 0.1170, P < 0.001) and between anterior and posterior regions (0.2159 ± 0.1538, P < 0.01) during ketamine anesthesia. Alpha power gradually decreased with subanesthetic ketamine, and anterior-to-posterior directed connectivity was maximally reduced (0.0282 ± 0.0772) during ketamine anesthesia compared to all other states (P < 0.05). CONCLUSIONS: Ketamine anesthesia correlates most clearly with distinct changes in the theta bandwidth, including increased power and functional connectivity. Anterior-to-posterior connectivity in the alpha bandwidth becomes maximally depressed with anesthetic ketamine administration, suggesting a dose-dependent effect.
BACKGROUND: Previous studies have demonstrated inconsistent neurophysiologic effects of ketamine, although discrepant findings might relate to differences in doses studied, brain regions analyzed, coadministration of other anesthetic medications, and resolution of the electroencephalograph. The objective of this study was to characterize the dose-dependent effects of ketamine on cortical oscillations and functional connectivity. METHODS: Ten healthy human volunteers were recruited for study participation. The data were recorded using a 128-channel electroencephalograph during baseline consciousness, subanesthetic dosing (0.5 mg/kg over 40 min), anesthetic dosing (1.5 mg/kg bolus), and recovery. No other sedative or anesthetic medications were administered. Spectrograms, topomaps, and functional connectivity (weighted and directed phase lag index) were computed and analyzed. RESULTS: Frontal theta bandwidth power increased most dramatically during ketamine anesthesia (mean power ± SD, 4.25 ± 1.90 dB) compared to the baseline (0.64 ± 0.28 dB), subanesthetic (0.60 ± 0.30 dB), and recovery (0.68 ± 0.41 dB) states; P < 0.001. Gamma power also increased during ketamine anesthesia. Weighted phase lag index demonstrated theta phase locking within anterior regions (0.2349 ± 0.1170, P < 0.001) and between anterior and posterior regions (0.2159 ± 0.1538, P < 0.01) during ketamine anesthesia. Alpha power gradually decreased with subanesthetic ketamine, and anterior-to-posterior directed connectivity was maximally reduced (0.0282 ± 0.0772) during ketamine anesthesia compared to all other states (P < 0.05). CONCLUSIONS:Ketamine anesthesia correlates most clearly with distinct changes in the theta bandwidth, including increased power and functional connectivity. Anterior-to-posterior connectivity in the alpha bandwidth becomes maximally depressed with anesthetic ketamine administration, suggesting a dose-dependent effect.
Authors: Emma M Whitham; Kenneth J Pope; Sean P Fitzgibbon; Trent Lewis; C Richard Clark; Stephen Loveless; Marita Broberg; Angus Wallace; Dylan DeLosAngeles; Peter Lillie; Andrew Hardy; Rik Fronsko; Alyson Pulbrook; John O Willoughby Journal: Clin Neurophysiol Date: 2007-06-15 Impact factor: 3.708
Authors: Emma M Whitham; Trent Lewis; Kenneth J Pope; Sean P Fitzgibbon; C Richard Clark; Stephen Loveless; Dylan DeLosAngeles; Angus K Wallace; Marita Broberg; John O Willoughby Journal: Clin Neurophysiol Date: 2008-03-10 Impact factor: 3.708
Authors: Laura D Lewis; Veronica S Weiner; Eran A Mukamel; Jacob A Donoghue; Emad N Eskandar; Joseph R Madsen; William S Anderson; Leigh R Hochberg; Sydney S Cash; Emery N Brown; Patrick L Purdon Journal: Proc Natl Acad Sci U S A Date: 2012-11-05 Impact factor: 11.205
Authors: Sounak Mohanta; Mohsen Afrasiabi; Cameron P Casey; Sean Tanabe; Michelle J Redinbaugh; Niranjan A Kambi; Jessica M Phillips; Daniel Polyakov; William Filbey; Joseph L Austerweil; Robert D Sanders; Yuri B Saalmann Journal: J Neurosci Date: 2021-11-03 Impact factor: 6.709
Authors: Charles William Carspecken; Sirisak Chanprasert; Franck Kalume; Margaret M Sedensky; Philip G Morgan Journal: Anesthesiology Date: 2018-10 Impact factor: 7.892
Authors: P E Vlisides; T Bel-Bahar; A Nelson; K Chilton; E Smith; E Janke; V Tarnal; P Picton; R E Harris; G A Mashour Journal: Br J Anaesth Date: 2018-04-13 Impact factor: 9.166