Active sleep-related depolarization of feline trigemino-thalamic afferent terminals.
Presynaptic depolarization of trigemino-thalamic (TGT) terminals may contribute to modulation of ascending oro-facial somatosensory information during active (or rapid eye movement) sleep. The relative excitability of TGT terminals was inferred from changes in the current required to maintain an antidromic firing probability of 50% (EC50) during quiet wakefulness as compared to active sleep. Depolarization or hyperpolarization of TGT terminals was defined as a decrease or increase, respectively, in the EC50. Overall, the EC50 of 8 TGT terminals was reduced by a mean 8.8+/-3.6 microA during active sleep relative to quiet wakefulness. This result suggests that depolarization of TGT terminals, which may act to suppress the transfer of sensory information from the trigeminal nucleus to the thalamus, occurs during active sleep.
Cairns
B E
BE
Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, Canada.
Soja
P J
PJ
D000200:Action Potentials; D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D001933:Brain Stem / Q000502:physiology; D002415:Cats; D004558:Electric Stimulation; D005154:Facial Nerve / Q000502:physiology; D007839:Functional Laterality; D006197:Hair; D008465:Mechanoreceptors / Q000502:physiology; D009411:Nerve Endings / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D011336:Probability; D012867:Skin / Q000294:innervation; D012895:Sleep, REM / Q000502:physiology*; D013569:Synapses / Q000502:physiology; D013788:Thalamus / Q000502:physiology*; D014276:Trigeminal Nerve / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology