title: Gamma band unit activity and population responses in the pedunculopontine nucleus.
abstract: The pedunculopontine nucleus (PPN) is involved in the activated states of waking and paradoxical sleep, forming part of the reticular activating system (RAS). The studies described tested the hypothesis that single unit and/or population responses of PPN neurons are capable of generating gamma band frequency activity. Whole cell patch clamp recordings (immersion chamber) and population responses (interface chamber) were conducted on 9- to 20-day-old rat brain stem slices. Regardless of cell type (I, II, or III) or type of response to the nonselective cholinergic receptor agonist carbachol (excitation, inhibition, biphasic), almost all PPN neurons fired at gamma band frequency, but no higher, when subjected to depolarizing steps (50 +/- 2 Hz, mean +/- SE). Nonaccommodating neurons fired at 18-100 Hz throughout depolarizing steps, while most accommodating neurons exhibited gamma band frequency of action potentials followed by gamma band membrane oscillations. These oscillations were blocked by the sodium channel blocker tetrodotoxin (TTX), suggesting that at least some are mediated by sodium currents. Population responses in the PPN showed that carbachol induced peaks of activation in the theta and gamma range, while glutamatergic receptor agonists induced overall increases in activity at theta and gamma frequencies, although in differing patterns. Gamma band activity appears to be a part of the intrinsic membrane properties of PPN neurons, and the population as a whole generates different patterns of gamma band activity under the influence of specific transmitters. Given sufficient excitation, the PPN may impart gamma band activation on its targets.
authors.affiliation: Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
authors.forename: Christen
authors.initials: C
authors.lastname: Simon
authors.forename: Nebojsa
authors.initials: N
authors.lastname: Kezunovic
authors.forename: Meijun
authors.initials: M
authors.lastname: Ye
authors.forename: James
authors.initials: J
authors.lastname: Hyde
authors.forename: A
authors.initials: A
authors.lastname: Hayar
authors.forename: D K
authors.initials: DK
authors.lastname: Williams
authors.forename: E
authors.initials: E
authors.lastname: Garcia-Rill
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D004569:Electroencephalography / Q000187:drug effects*; D055724:Electrophysiological Phenomena; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005260:Female; D007608:Kainic Acid / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018721:Muscarinic Agonists / Q000494:pharmacology; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D045042:Pedunculopontine Tegmental Nucleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D013826:Theta Rhythm / Q000187:drug effects
chemical_list: D018690:Excitatory Amino Acid Agonists; D018721:Muscarinic Agonists; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D026941:Sodium Channel Blockers; D013779:Tetrodotoxin; D016202:N-Methylaspartate; D002217:Carbachol; D007608:Kainic Acid
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