title: Phase-amplitude coupled persistent theta and gamma oscillations in rat primary motor cortex in vitro.
abstract: In vivo, theta (4-7 Hz) and gamma (30-80 Hz) neuronal network oscillations are known to coexist and display phase-amplitude coupling (PAC). However, in vitro, these oscillations have for many years been studied in isolation. Using an improved brain slice preparation technique we have, using co-application of carbachol (10 μM) and kainic acid (150 nM), elicited simultaneous theta (6.6 ± 0.1 Hz) and gamma (36.6 ± 0.4 Hz) oscillations in rodent primary motor cortex (M1). Each oscillation showed greatest power in layer V. Using a variety of time series analyses we detected significant cross-frequency coupling in 74% of slice preparations. Differences were observed in the pharmacological profile of each oscillation. Thus, gamma oscillations were reduced by the GABAAreceptor antagonists, gabazine (250 nM and 2 μM), and picrotoxin (50 μM) and augmented by AMPA receptor antagonism with SYM2206 (20 μM). In contrast, theta oscillatory power was increased by gabazine, picrotoxin and SYM2206. GABABreceptor blockade with CGP55845 (5 μM) increased both theta and gamma power, and similar effects were seen with diazepam, zolpidem, MK801 and a series of metabotropic glutamate receptor antagonists. Oscillatory activity at both frequencies was reduced by the gap junction blocker carbenoxolone (200 μM) and by atropine (5 μM). These data show theta and gamma oscillations in layer V of rat M1 in vitro are cross-frequency coupled, and are mechanistically distinct. The development of an in vitro model of phase-amplitude coupled oscillations will facilitate further mechanistic investigation of the generation and modulation of coupled activity in mammalian cortex.
authors.affiliation: Aston Brain Centre, Aston University, School of Life and Health Sciences, Birmingham, B4 7ET, United Kingdom.
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Johnson
authors.affiliation: Department of Anatomy, School of Medicine, Marmara University, Istanbul, Turkey.
authors.forename: Mazhar
authors.initials: M
authors.lastname: Özkan
authors.affiliation: Aston Brain Centre, Aston University, School of Life and Health Sciences, Birmingham, B4 7ET, United Kingdom.
authors.forename: Adrian P
authors.initials: AP
authors.lastname: Burgess
authors.affiliation: Aston Brain Centre, Aston University, School of Life and Health Sciences, Birmingham, B4 7ET, United Kingdom.
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Prokic
authors.affiliation: Neuroscience Division, Eli Lilly & Co. Ltd., Windlesham, GU20 6PH, United Kingdom.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Wafford
authors.affiliation: Neuroscience Division, Eli Lilly & Co. Ltd., Windlesham, GU20 6PH, United Kingdom.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: O'Neill
authors.affiliation: Aston Brain Centre, Aston University, School of Life and Health Sciences, Birmingham, B4 7ET, United Kingdom.
authors.forename: Stuart D
authors.initials: SD
authors.lastname: Greenhill
authors.affiliation: Aston Brain Centre, Aston University, School of Life and Health Sciences, Birmingham, B4 7ET, United Kingdom.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Stanford
authors.affiliation: Aston Brain Centre, Aston University, School of Life and Health Sciences, Birmingham, B4 7ET, United Kingdom. Electronic address: G.L.Woodhall@aston.ac.uk.
authors.forename: Gavin L
authors.initials: GL
authors.lastname: Woodhall
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists; D065818:Gamma Rhythm / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D009044:Motor Cortex / Q000187:drug effects / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018079:Receptors, GABA / Q000378:metabolism; D013826:Theta Rhythm / Q000187:drug effects / Q000502:physiology*
chemical_list: D018679:Cholinergic Agonists; D018690:Excitatory Amino Acid Agonists; D018377:Neurotransmitter Agents; D018079:Receptors, GABA; D002217:Carbachol; D007608:Kainic Acid
keywords: Gamma; M1; Neuronal network oscillations; Phase amplitude coupling; Theta