Increased responsiveness of cortical neurons in contrast to thalamic neurons during isoflurane-induced EEG bursts in rats.
The neuronal mechanisms underlying the electroencephalographic (EEG) burst-suppression pattern are not yet understood, however, they are generally attributed to interactions within thalamocortical networks. In contrast, we report that the sensory cortex and the thalamus are disconnected, with thalamic sensory processing being unaffected by cortical EEG bursts. We studied the activity of single neurons of the somatosensory thalamocortical system in rats during burst-suppression EEG induced by the volatile anesthetic, isoflurane. In neurons of the thalamic ventrobasal complex, the discharge rate in response to tactile stimulation of their receptive fields did not differ significantly during EEG bursts and isoelectric periods. In contrast, in neurons of the primary somatosensory cortex, the response magnitude was significantly greater during EEG bursts as compared with isoelectric periods (mean increase to 293%). The results suggest that the profound suppression of cortical sensory information processing by isoflurane is suspended during EEG burst-induced elevated cortical excitation.
Detsch
Oliver
O
Klinik für Anaesthesiologie, Technische Universität München, Munich, Germany.
Kochs
Eberhard
E
Siemers
Matthias
M
Bromm
Burkhart
B
Vahle-Hinz
Christiane
C
D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D004569:Electroencephalography / Q000187:drug effects*; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects / Q000502:physiology; D007530:Isoflurane / Q000494:pharmacology*; D008465:Mechanoreceptors / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects* / Q000502:physiology; D009434:Neural Pathways / Q000187:drug effects* / Q000502:physiology; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D013003:Somatosensory Cortex / Q000187:drug effects* / Q000502:physiology; D020651:Ventral Thalamic Nuclei / Q000187:drug effects* / Q000502:physiology; D014738:Vibrissae / Q000187:drug effects / Q000502:physiology
D018685:Anesthetics, Inhalation; D007530:Isoflurane