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Chen RYT, Evans RC. Comparing tonic and phasic dendritic calcium in cholinergic pedunculopontine neurons and dopaminergic substantia nigra neurons. Eur J Neurosci 2024; 59:1638-1656. [PMID: 38383047 PMCID: PMC10987283 DOI: 10.1111/ejn.16281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 01/25/2024] [Accepted: 01/30/2024] [Indexed: 02/23/2024]
Abstract
Several brainstem nuclei degenerate in Parkinson's disease (PD). In addition to the well-characterized dopaminergic neurons of the substantia nigra pars compacta (SNc), the cholinergic neurons of the pedunculopontine nucleus (PPN) also degenerate in PD. One leading hypothesis of selective vulnerability is that pacemaking activity and the activation of low-threshold L-type calcium current are major contributors to tonic calcium load and cellular stress in SNc dopaminergic neurons. However, it is not yet clear whether the vulnerable PPN cholinergic neurons share this property. Therefore, we used two-photon dendritic calcium imaging and whole-cell electrophysiology to evaluate the role of L-type calcium channels in tonic and phasic dendritic calcium signals in PPN and SNc neurons. In addition, we investigated N- and P/Q-type calcium channel regulation of firing properties and dendritic calcium in PPN neurons. We found that blocking L-type channels reduces tonic firing rate and dendritic calcium levels in SNc neurons. By contrast, the tonic calcium load in PPN neurons did not depend on L-, N- or P/Q-type channels. However, we found that blocking either L-type (with nifedipine) or N- and P/Q-type (with omega-conotoxin MVIIC) channels reduces phasic calcium influx in PPN dendrites. Together, these findings show that L-type calcium channels play different roles in the activity of SNc and PPN neurons, and suggest that low-threshold L-type channels are not responsible for tonic calcium levels in PPN cholinergic neurons and are therefore not likely to be a source of selective vulnerability in these cells.
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Affiliation(s)
- Rita Yu-Tzu Chen
- Department of Neuroscience, Georgetown University Medical Center, Washington DC
| | - Rebekah C. Evans
- Department of Neuroscience, Georgetown University Medical Center, Washington DC
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Khamis H, Cohen O. Coupled action potential and calcium dynamics underlie robust spontaneous firing in dopaminergic neurons. Phys Biol 2024; 21:026005. [PMID: 38382117 DOI: 10.1088/1478-3975/ad2bd4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 02/21/2024] [Indexed: 02/23/2024]
Abstract
Dopaminergic neurons are specialized cells in the substantia nigra, tasked with dopamine secretion. This secretion relies on intracellular calcium signaling coupled to neuronal electrical activity. These neurons are known to display spontaneous calcium oscillationsin-vitroandin-vivo, even in synaptic isolation, controlling the basal dopamine levels. Here we outline a kinetic model for the ion exchange across the neuronal plasma membrane. Crucially, we relax the assumption of constant, cytoplasmic sodium and potassium concentration. We show that sodium-potassium dynamics are strongly coupled to calcium dynamics and are essential for the robustness of spontaneous firing frequency. The model predicts several regimes of electrical activity, including tonic and 'burst' oscillations, and predicts the switch between those in response to perturbations. 'Bursting' correlates with increased calcium amplitudes, while maintaining constant average, allowing for a vast change in the calcium signal responsible for dopamine secretion. All the above traits provide the flexibility to create rich action potential dynamics that are crucial for cellular function.
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Affiliation(s)
- Hadeel Khamis
- Gateway Institute for Brain Research, Fort Lauderdale, FL 33314, United States of America
| | - Ohad Cohen
- Gateway Institute for Brain Research, Fort Lauderdale, FL 33314, United States of America
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3
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Chen RYT, Evans RC. Comparing tonic and phasic calcium in the dendrites of vulnerable midbrain neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555184. [PMID: 37693427 PMCID: PMC10491175 DOI: 10.1101/2023.08.28.555184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Several midbrain nuclei degenerate in Parkinson's Disease (PD). Many of these nuclei share the common characteristics that are thought to contribute to their selective vulnerability, including pacemaking activity and high levels of calcium influx. In addition to the well-characterized dopaminergic neurons of the substantia nigra pars compacta (SNc), the cholinergic neurons of the pedunculopontine nucleus (PPN) also degenerate in PD. It is well established that the low-threshold L-type calcium current is a main contributor to tonic calcium in SNc dopaminergic neurons and is hypothesized to contribute to their selective vulnerability. However, it is not yet clear whether the vulnerable PPN cholinergic neurons share this property. Therefore, we used two-photon dendritic calcium imaging and whole-cell electrophysiology to evaluate the role of L-type calcium channels in the tonic and phasic activity of PPN neurons and the corresponding dendritic calcium signal and directly compare these characteristics to SNc neurons. We found that blocking L-type channels reduces tonic firing rate and dendritic calcium levels in SNc neurons. By contrast, the calcium load in PPN neurons during pacemaking did not depend on L-type channels. However, we find that blocking L-type channels reduces phasic calcium influx in PPN dendrites. Together, these findings show that L-type calcium channels play different roles in the activity of SNc and PPN neurons, and suggest that low-threshold L-type channels are not responsible for tonic calcium levels in PPN cholinergic neurons and are therefore not likely to be a source of selective vulnerability in these cells.
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Affiliation(s)
- Rita Yu-Tzu Chen
- Department of Neuroscience, Georgetown University Medical Center, Washington DC
| | - Rebekah C. Evans
- Department of Neuroscience, Georgetown University Medical Center, Washington DC
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Garcia-Rill E, Urbano FJ. Concerns regarding Baksa B, Kovacs A, Bayasgalan T, Szentesi P, Koseghy A, Szucs P, Balazs P. Characterization of functional subgroups among genetically identified cholinergic neurons in the pedunculopontine nucleus. Cell Molec. Life Sci. 2019-04-02. Cell Mol Life Sci 2019; 76:4581-4582. [PMID: 31570964 PMCID: PMC6858958 DOI: 10.1007/s00018-019-03307-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 08/19/2019] [Accepted: 09/16/2019] [Indexed: 01/07/2023]
Affiliation(s)
- Edgar Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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Byrum SD, Washam CL, Tackett AJ, Garcia-Rill E, Bisagno V, Urbano FJ. Proteomic measures of gamma oscillations. Heliyon 2019; 5:e02265. [PMID: 31497668 PMCID: PMC6722265 DOI: 10.1016/j.heliyon.2019.e02265] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 05/23/2019] [Accepted: 08/06/2019] [Indexed: 02/01/2023] Open
Abstract
Background Gamma oscillations serve complex processes, and the first stage of their generation is the reticular activating system (RAS), which mediates the gamma-activity states of waking and paradoxical sleep. We studied whether the pedunculopontine nucleus (PPN), part of the RAS in which every cell manifests intrinsic gamma oscillations, undergoes changes resulting in distinctive protein expression. New method We previously found that a histone deacetylation inhibitor, trichostatin A (TSA), acutely (30 min) blocked these oscillations. We developed a proteomic method for sampling stimulated and unstimulated PPN and determining protein expression in 1 mm punches of tissue from brain slices subjected to various treatments. Results We compared brain slices exposed for 30 min to TSA (unstimulated), to the cholinergic agonist carbachol (CAR), known to induce PPN gamma oscillations, or exposed to both TSA + CAR. Comparison with existing methods: Label-free proteomics provides an unbiased and sensitive method to detect protein changes in the PPN. Our approach is superior to antibody-based methods that can lack specificity and can only be done for known targets. Proteomics methods like these have been leveraged to study molecular pathways in numerous systems and disease states. Conclusions Significant protein changes were seen in two functions essential to the physiology of the PPN: cytoskeletal and intracellular [Ca2+] regulation proteins. TSA decreased, while CAR increased, and TSA + CAR had intermediate effects, on expression of these proteins. These results support the feasibility of the methods developed for determining proteomic changes in small samples of tissue participating in the most complex of brain processes.
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Affiliation(s)
- Stephanie D Byrum
- Center for Translational Pediatric Research, Arkansas Children's Research Institute, Little Rock, AR, USA
| | - Charity L Washam
- Center for Translational Pediatric Research, Arkansas Children's Research Institute, Little Rock, AR, USA
| | - Alan J Tackett
- Center for Translational Pediatric Research, Arkansas Children's Research Institute, Little Rock, AR, USA
| | - Edgar Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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Garcia-Rill E, Saper CB, Rye DB, Kofler M, Nonnekes J, Lozano A, Valls-Solé J, Hallett M. Focus on the pedunculopontine nucleus. Consensus review from the May 2018 brainstem society meeting in Washington, DC, USA. Clin Neurophysiol 2019; 130:925-940. [PMID: 30981899 PMCID: PMC7365492 DOI: 10.1016/j.clinph.2019.03.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 03/15/2019] [Accepted: 03/22/2019] [Indexed: 12/12/2022]
Abstract
The pedunculopontine nucleus (PPN) is located in the mesopontine tegmentum and is best delimited by a group of large cholinergic neurons adjacent to the decussation of the superior cerebellar peduncle. This part of the brain, populated by many other neuronal groups, is a crossroads for many important functions. Good evidence relates the PPN to control of reflex reactions, sleep-wake cycles, posture and gait. However, the precise role of the PPN in all these functions has been controversial and there still are uncertainties in the functional anatomy and physiology of the nucleus. It is difficult to grasp the extent of the influence of the PPN, not only because of its varied functions and projections, but also because of the controversies arising from them. One controversy is its relationship to the mesencephalic locomotor region (MLR). In this regard, the PPN has become a new target for deep brain stimulation (DBS) for the treatment of parkinsonian gait disorders, including freezing of gait. This review is intended to indicate what is currently known, shed some light on the controversies that have arisen, and to provide a framework for future research.
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Affiliation(s)
- E Garcia-Rill
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
| | - C B Saper
- Department of Neurology, Division of Sleep Medicine and Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - David B Rye
- Department of Neurology, Division of Sleep Medicine and Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - M Kofler
- Department of Neurology, Hochzirl Hospital, Zirl, Austria
| | - J Nonnekes
- Radboud University Medical Centre, Donders Institute for Brain, Cognition and Behaviour, Department of Rehabilitation, Nijmegen, the Netherlands
| | - A Lozano
- Division of Neurosurgery, University of Toronto and Krembil Neuroscience Centre, University Health Network, Toronto, Canada
| | - J Valls-Solé
- Neurology Department, Hospital Clínic, University of Barcelona, IDIBAPS (Institut d'Investigació Biomèdica August Pi i Sunyer), Barcelona, Spain
| | - M Hallett
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
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Local and Relayed Effects of Deep Brain Stimulation of the Pedunculopontine Nucleus. Brain Sci 2019; 9:brainsci9030064. [PMID: 30889866 PMCID: PMC6468768 DOI: 10.3390/brainsci9030064] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 03/12/2019] [Accepted: 03/13/2019] [Indexed: 12/18/2022] Open
Abstract
Our discovery of low-threshold stimulation-induced locomotion in the pedunculopontine nucleus (PPN) led to the clinical use of deep brain stimulation (DBS) for the treatment of disorders such as Parkinson's disease (PD) that manifest gait and postural disorders. Three additional major discoveries on the properties of PPN neurons have opened new areas of research for the treatment of motor and arousal disorders. The description of (a) electrical coupling, (b) intrinsic gamma oscillations, and (c) gene regulation in the PPN has identified a number of novel therapeutic targets and methods for the treatment of a number of neurological and psychiatric disorders. We first delve into the circuit, cellular, intracellular, and molecular organization of the PPN, and then consider the clinical results to date on PPN DBS. This comprehensive review will provide valuable information to explain the network effects of PPN DBS, point to new directions for treatment, and highlight a number of issues related to PPN DBS.
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8
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Garcia‐Rill E, D'Onofrio S, Mahaffey SC, Bisagno V, Urbano FJ. Bottom-up gamma and bipolar disorder, clinical and neuroepigenetic implications. Bipolar Disord 2019; 21:108-116. [PMID: 30506611 PMCID: PMC6441386 DOI: 10.1111/bdi.12735] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVES This limited review examines the role of the reticular activating system (RAS), especially the pedunculopontine nucleus (PPN), one site of origin of bottom-up gamma, in the symptoms of bipolar disorder (BD). METHODS The expression of neuronal calcium sensor protein 1 (NCS-1) in the brains of BD patients is increased. It has recently been found that all PPN neurons manifest intrinsic membrane beta/gamma frequency oscillations mediated by high threshold calcium channels, suggesting that it is one source of bottom-up gamma. This review specifically addresses the involvement of these channels in the manifestation of BD. RESULTS Excess NCS-1 was found to dampen gamma band oscillations in PPN neurons. Lithium, a first line treatment for BD, was found to decrease the effects of NCS-1 on gamma band oscillations in PPN neurons. Moreover, gamma band oscillations appear to epigenetically modulate gene transcription in PPN neurons, providing a new direction for research in BD. CONCLUSIONS This is an area needing much additional research, especially since the dysregulation of calcium channels may help explain many of the disorders of arousal in, elicit unwanted neuroepigenetic modulation in, and point to novel therapeutic avenues for, BD.
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Affiliation(s)
- Edgar Garcia‐Rill
- Center for Translational NeuroscienceUniversity of Arkansas for Medical SciencesLittle RockArkansas
| | - Stasia D'Onofrio
- Center for Translational NeuroscienceUniversity of Arkansas for Medical SciencesLittle RockArkansas
| | - Susan C Mahaffey
- Center for Translational NeuroscienceUniversity of Arkansas for Medical SciencesLittle RockArkansas
| | - Veronica Bisagno
- Center for Translational NeuroscienceUniversity of Arkansas for Medical SciencesLittle RockArkansas,IFIBYNECONICETUniversidad de Buenos AiresBuenos AiresArgentina
| | - Francisco J Urbano
- Center for Translational NeuroscienceUniversity of Arkansas for Medical SciencesLittle RockArkansas,IFIBYNECONICETUniversidad de Buenos AiresBuenos AiresArgentina
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Wen Q, Gao S, Zhen M. Caenorhabditis elegans excitatory ventral cord motor neurons derive rhythm for body undulation. Philos Trans R Soc Lond B Biol Sci 2018; 373:rstb.2017.0370. [PMID: 30201835 DOI: 10.1098/rstb.2017.0370] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2018] [Indexed: 12/25/2022] Open
Abstract
The intrinsic oscillatory activity of central pattern generators underlies motor rhythm. We review and discuss recent findings that address the origin of Caenorhabditis elegans motor rhythm. These studies propose that the A- and mid-body B-class excitatory motor neurons at the ventral cord function as non-bursting intrinsic oscillators to underlie body undulation during reversal and forward movements, respectively. Proprioception entrains their intrinsic activities, allows phase-coupling between members of the same class motor neurons, and thereby facilitates directional propagation of undulations. Distinct pools of premotor interneurons project along the ventral nerve cord to innervate all members of the A- and B-class motor neurons, modulating their oscillations, as well as promoting their bi-directional coupling. The two motor sub-circuits, which consist of oscillators and descending inputs with distinct properties, form the structural base of dynamic rhythmicity and flexible partition of the forward and backward motor states. These results contribute to a continuous effort to establish a mechanistic and dynamic model of the C. elegans sensorimotor system. C. elegans exhibits rich sensorimotor functions despite a small neuron number. These findings implicate a circuit-level functional compression. By integrating the role of rhythm generation and proprioception into motor neurons, and the role of descending regulation of oscillators into premotor interneurons, this numerically simple nervous system can achieve a circuit infrastructure analogous to that of anatomically complex systems. C. elegans has manifested itself as a compact model to search for general principles of sensorimotor behaviours.This article is part of a discussion meeting issue 'Connectome to behaviour: modelling C. elegans at cellular resolution'.
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Affiliation(s)
- Quan Wen
- Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei 230027, People's Republic of China .,Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, People's Republic of China
| | - Shangbang Gao
- College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
| | - Mei Zhen
- The Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital; Department of Molecular Genetics, Department of Physiology, University of Toronto, Toronto, Ontario M5G 1XS, Canada
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10
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Gao S, Guan SA, Fouad AD, Meng J, Kawano T, Huang YC, Li Y, Alcaire S, Hung W, Lu Y, Qi YB, Jin Y, Alkema M, Fang-Yen C, Zhen M. Excitatory motor neurons are local oscillators for backward locomotion. eLife 2018; 7:e29915. [PMID: 29360035 PMCID: PMC5780044 DOI: 10.7554/elife.29915] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 10/22/2017] [Indexed: 01/16/2023] Open
Abstract
Cell- or network-driven oscillators underlie motor rhythmicity. The identity of C. elegans oscillators remains unknown. Through cell ablation, electrophysiology, and calcium imaging, we show: (1) forward and backward locomotion is driven by different oscillators; (2) the cholinergic and excitatory A-class motor neurons exhibit intrinsic and oscillatory activity that is sufficient to drive backward locomotion in the absence of premotor interneurons; (3) the UNC-2 P/Q/N high-voltage-activated calcium current underlies A motor neuron's oscillation; (4) descending premotor interneurons AVA, via an evolutionarily conserved, mixed gap junction and chemical synapse configuration, exert state-dependent inhibition and potentiation of A motor neuron's intrinsic activity to regulate backward locomotion. Thus, motor neurons themselves derive rhythms, which are dually regulated by the descending interneurons to control the reversal motor state. These and previous findings exemplify compression: essential circuit properties are conserved but executed by fewer numbers and layers of neurons in a small locomotor network.
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Affiliation(s)
- Shangbang Gao
- Key Laboratory of Molecular Biophysics of the Ministry of EducationCollege of Life Science and Technology, Huazhong University of Science and TechnologyWuhanChina
| | - Sihui Asuka Guan
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoCanada
- Department of PhysiologyUniversity of TorontoTorontoCanada
| | - Anthony D Fouad
- Department of BioengineeringSchool of Engineering and Applied Science, University of PennsylvaniaPhiladelphiaUnited States
| | - Jun Meng
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoCanada
- Department of PhysiologyUniversity of TorontoTorontoCanada
| | - Taizo Kawano
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Yung-Chi Huang
- Department of NeurobiologyUniversity of Massachusetts Medical SchoolWorcesterUnited States
| | - Yi Li
- Key Laboratory of Molecular Biophysics of the Ministry of EducationCollege of Life Science and Technology, Huazhong University of Science and TechnologyWuhanChina
| | - Salvador Alcaire
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoCanada
- Department of PhysiologyUniversity of TorontoTorontoCanada
| | - Wesley Hung
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Yangning Lu
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoCanada
- Department of PhysiologyUniversity of TorontoTorontoCanada
| | - Yingchuan Billy Qi
- Neurobiology Section, Division of Biological SciencesUniversity of CaliforniaSan DiegoUnited States
| | - Yishi Jin
- Neurobiology Section, Division of Biological SciencesUniversity of CaliforniaSan DiegoUnited States
| | - Mark Alkema
- Department of NeurobiologyUniversity of Massachusetts Medical SchoolWorcesterUnited States
| | - Christopher Fang-Yen
- Department of BioengineeringSchool of Engineering and Applied Science, University of PennsylvaniaPhiladelphiaUnited States
- Department of NeuroscienceUniversity of PennsylvaniaPhiladelphiaUnited States
| | - Mei Zhen
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
- Department of Molecular GeneticsUniversity of TorontoTorontoCanada
- Department of PhysiologyUniversity of TorontoTorontoCanada
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Garcia-Rill E, Mahaffey S, Hyde JR, Urbano FJ. Bottom-up gamma maintenance in various disorders. Neurobiol Dis 2018; 128:31-39. [PMID: 29353013 DOI: 10.1016/j.nbd.2018.01.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 01/02/2018] [Accepted: 01/10/2018] [Indexed: 11/30/2022] Open
Abstract
Maintained gamma band activity is a key element of higher brain function, participating in perception, executive function, and memory. The pedunculopontine nucleus (PPN), as part of the reticular activating system (RAS), is a major source of the "bottom-up" flow of gamma activity to higher regions. However, interruption of gamma band activity is associated with a number of neurological and psychiatric disorders. This review will focus on the role of the PPN in activating higher regions to induce arousal and descending pathways to modulate posture and locomotion. As such, PPN deep brain stimulation (DBS) can not only help regulate arousal and stepping, but continuous application may help maintain necessary levels of gamma band activity for a host of other brain processes. We will explore the potential future applications of PPN DBS for a number of disorders that are characterized by disturbances in gamma band maintenance.
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Affiliation(s)
- E Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
| | - S Mahaffey
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | | | - F J Urbano
- IFIBYNE (CONICET-UBA), DFBMC, Universidad de Buenos Aires, Buenos Aires, Argentina
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12
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Urbano FJ, Bisagno V, Garcia-Rill E. Arousal and drug abuse. Behav Brain Res 2017; 333:276-281. [PMID: 28729115 DOI: 10.1016/j.bbr.2017.07.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/08/2017] [Accepted: 07/14/2017] [Indexed: 12/31/2022]
Abstract
The reticular activating system (RAS) is not an amorphous region but distinct nuclei with specific membrane properties that dictate their firing during waking and sleep. The locus coeruleus and raphe nucleus fire during waking and slow wave sleep, with the pedunculopontine nucleus (PPN) firing during both waking and REM sleep, the states manifesting arousal-related EEG activity. Two important discoveries in the PPN in the last 10 years are, 1) that some PPN cells are electrically coupled, and 2) every PPN cell manifests high threshold calcium channels that allow them to oscillate at beta/gamma band frequencies. The role of arousal in drug abuse is considered here in terms of the effects of drugs of abuse on these two mechanisms. Drug abuse and the perception of withdrawal/relapse are mediated by neurobiological processes that occur only when we are awake, not when we are asleep. These relationships focus on the potential role of arousal, more specifically of RAS electrical coupling and gamma band activity, in the addictive process as well as the relapse to drug use.
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Affiliation(s)
| | - Verónica Bisagno
- IFIBYNE-CONICET, ININFA-CONICET, University of Buenos Aires, Argentina
| | - Edgar Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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13
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Garcia-Rill E. Bottom-up gamma and stages of waking. Med Hypotheses 2017; 104:58-62. [PMID: 28673592 DOI: 10.1016/j.mehy.2017.05.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 05/22/2017] [Accepted: 05/25/2017] [Indexed: 11/25/2022]
Abstract
Gamma activity has been proposed to promote the feed forward or "bottom-up" flow of information from lower to higher regions of the brain during perception. The pedunculopontine nucleus (PPN) modulates waking and REM sleep, and is part of the reticular activating system (RAS). The properties of PPN cells are unique in that all PPN neurons fire maximally at gamma band frequency regardless of electrophysiological or transmitter type, thus proposed as one origin of "bottom-up" gamma. This property is based on the presence of intrinsic membrane oscillations subserved by high threshold, voltage-dependent calcium channels. Moreover, some PPN cells are electrically coupled. Assuming that the population of PPN neurons has the capacity to fire at ∼40Hz coherently, then the population as a whole can be expected to generate a stable gamma band signal. But what if not all the neurons are firing at the peaks of the oscillations? That means that some cells may fire only at the peaks of every second oscillation. Therefore, the population as a whole can be expected to be firing at a net ∼20Hz. If some cells are firing at the peaks of every fourth oscillation, then the PPN as a whole would be firing at ∼10Hz. Firing at rates below 10Hz would imply that the system is seldom firing at the peaks of any oscillation, basically asleep, in slow wave sleep, thus the activation of the RAS is insufficient to promote waking. This hypothesis carries certain implications, one of which is that we awaken in stages as more and more cells are recruited to fire at the peaks of more and more oscillations. For this system, it would imply that, as we awaken, we step from ∼10Hz to ∼20Hz to ∼30Hz to ∼40Hz, that is, in stages and presumably at different levels of awareness. A similar process can be expected to take place as we fall asleep. Awakening can then be considered to be stepwise, not linear. That is, the implication is that the process of waking is a stepwise event, not a gradual increase, suggesting that the brain can spend time at each of these different stages of arousal.
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Affiliation(s)
- E Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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14
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Garcia-Rill E, D’Onofrio S, Mahaffey S. Bottom-up Gamma: the Pedunculopontine Nucleus and Reticular Activating System. TRANSLATIONAL BRAIN RHYTHMICITY 2016; 1:49-53. [PMID: 28691105 PMCID: PMC5497760 DOI: 10.15761/tbr.1000109] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Gamma rhythms have been proposed to promote the feed forward or "bottom-up" flow of information from lower to higher regions in the brain during perception. On the other hand, beta rhythms have been proposed to represent feed back or "top-down" influence from higher regions to lower. The pedunculopontine nucleus (PPN) has been implicated in sleep-wake control and arousal, and is part of the reticular activating system (RAS). This review describes the properties of the cells in this nucleus. These properties are unique, and perhaps it is the particular characteristics of these cells that allow the PPN to be involved in a host of functions and disorders. The fact that all PPN neurons fire maximally at gamma band frequency regardless of electrophysiological or transmitter type, make this an unusual cell group. In other regions, for example in the cortex, cells with such a property represent only a sub-population. More importantly, the fact that this cell group's functions are related to the capacity to generate coherent activity at a preferred natural frequency, gamma band, speaks volumes about how the PPN functions. We propose that "bottom-up" gamma band influence arises in the RAS and contributes to the build-up of the background of activity necessary for preconscious awareness and gamma activity at cortical levels.
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Affiliation(s)
- E. Garcia-Rill
- Center for Translational Neuroscience, Department of Neurobiology, University of Arkansas for Medical Sciences., Little Rock, AR
| | - S. D’Onofrio
- Center for Translational Neuroscience, Department of Neurobiology, University of Arkansas for Medical Sciences., Little Rock, AR
| | - S. Mahaffey
- Center for Translational Neuroscience, Department of Neurobiology, University of Arkansas for Medical Sciences., Little Rock, AR
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Luster BR, Urbano FJ, Garcia-Rill E. Intracellular mechanisms modulating gamma band activity in the pedunculopontine nucleus (PPN). Physiol Rep 2016; 4:4/12/e12787. [PMID: 27354537 PMCID: PMC4923228 DOI: 10.14814/phy2.12787] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 04/11/2016] [Indexed: 02/04/2023] Open
Abstract
The pedunculopontine nucleus is a part of the reticular activating system, and is active during waking and REM sleep. Previous results showed that all PPN cells tested fired maximally at gamma frequencies when depolarized. This intrinsic membrane property was shown to be mediated by high‐threshold N‐ and P/Q‐type Ca2+ channels. Recent studies show that the PPN contains three independent populations of neurons which can generate gamma band oscillations through only N‐type channels, only P/Q‐type channels, or both N‐ and P/Q‐type channels. This study investigated the intracellular mechanisms modulating gamma band activity in each population of neurons. We performed in vitro patch‐clamp recordings of PPN neurons from Sprague–Dawley rat pups, and applied 1‐sec ramps to induce intrinsic membrane oscillations. Our results show that there are two pathways modulating gamma band activity in PPN neurons. We describe populations of neurons mediating gamma band activity through only N‐type channels and the cAMP/PKA pathway (presumed “REM‐on” neurons), through only P/Q‐type channels and the CaMKII pathway (presumed “Wake‐on” neurons), and a third population which can mediate gamma activity through both N‐type channels and cAMP/PK and P/Q‐type channels and CaMKII (presumed “Wake/REM‐on” neurons). These novel results suggest that PPN gamma oscillations are modulated by two independent pathways related to different Ca2+ channel types.
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Affiliation(s)
- Brennon R Luster
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | | | - Edgar Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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Urbano FJ, Luster BR, D'Onofrio S, Mahaffey S, Garcia-Rill E. Recording Gamma Band Oscillations in Pedunculopontine Nucleus Neurons. J Vis Exp 2016. [PMID: 27684729 DOI: 10.3791/54685] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Synaptic efferents from the PPN are known to modulate the neuronal activity of several intralaminar thalamic regions (e.g., the centrolateral/parafascicular; Cl/Pf nucleus). The activation of either the PPN or Cl/Pf nuclei in vivo has been described to induce the arousal of the animal and an increment in gamma band activity in the cortical electroencephalogram (EEG). The cellular mechanisms for the generation of gamma band oscillations in Reticular Activating System (RAS) neurons are the same as those found to generate gamma band oscillations in other brains nuclei. During current-clamp recordings of PPN neurons (from parasagittal slices from 9 - 25 day-old rats), the use of depolarizing square steps rapidly activated voltage-dependent potassium channels that prevented PPN neurons from being depolarized beyond -25 mV. Injecting 1 - 2 sec long depolarizing current ramps gradually depolarized PPN membrane potential resting values towards 0 mV. However, injecting depolarizing square pulses generated gamma-band oscillations of membrane potential that showed to be smaller in amplitude compared to the oscillations generated by ramps. All experiments were performed in the presence of voltage-gated sodium channels and fast synaptic receptors blockers. It has been shown that the activation of high-threshold voltage-dependent calcium channels underlie gamma-band oscillatory activity in PPN neurons. Specific methodological and pharmacological interventions are described here, providing the necessary tools to induce and sustain PPN subthreshold gamma band oscillation in vitro.
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Affiliation(s)
| | - Brennon R Luster
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences
| | - Stasia D'Onofrio
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences
| | - Susan Mahaffey
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences
| | - Edgar Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences;
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Garcia-Rill E, Luster B, D'Onofrio S, Mahaffey S, Bisagno V, Urbano FJ. Implications of gamma band activity in the pedunculopontine nucleus. J Neural Transm (Vienna) 2016; 123:655-665. [PMID: 26597124 PMCID: PMC4877293 DOI: 10.1007/s00702-015-1485-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 11/10/2015] [Indexed: 01/07/2023]
Abstract
The fact that the pedunculopontine nucleus (PPN) is part of the reticular activating system places it in a unique position to modulate sensory input and fight-or-flight responses. Arousing stimuli simultaneously activate ascending projections of the PPN to the intralaminar thalamus to trigger cortical high-frequency activity and arousal, as well as descending projections to reticulospinal systems to alter posture and locomotion. As such, the PPN has become a target for deep brain stimulation for the treatment of Parkinson's disease, modulating gait, posture, and higher functions. This article describes the latest discoveries on PPN physiology and the role of the PPN in a number of disorders. It has now been determined that high-frequency activity during waking and REM sleep is controlled by two different intracellular pathways and two calcium channels in PPN cells. Moreover, there are three different PPN cell types that have one or both calcium channels and may be active during waking only, REM sleep only, or both. Based on the new discoveries, novel mechanisms are proposed for insomnia as a waking disorder. In addition, neuronal calcium sensor protein-1 (NCS-1), which is over expressed in schizophrenia and bipolar disorder, may be responsible for the dysregulation in gamma band activity in at least some patients with these diseases. Recent results suggest that NCS-1 modulates PPN gamma band activity and that lithium acts to reduce the effects of over expressed NCS-1, accounting for its effectiveness in bipolar disorder.
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Affiliation(s)
- E Garcia-Rill
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Slot 847, 4301 West Markham St., Little Rock, AR, 72205, USA.
| | - B Luster
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Slot 847, 4301 West Markham St., Little Rock, AR, 72205, USA
| | - S D'Onofrio
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Slot 847, 4301 West Markham St., Little Rock, AR, 72205, USA
| | - S Mahaffey
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Slot 847, 4301 West Markham St., Little Rock, AR, 72205, USA
| | - V Bisagno
- IFIBYNE-CONICET, ININFA-CONICET, University of Buenos Aires, Buenos Aires, Argentina
| | - F J Urbano
- IFIBYNE-CONICET, ININFA-CONICET, University of Buenos Aires, Buenos Aires, Argentina
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Salakhieva DV, Sadreev II, Chen MZQ, Umezawa Y, Evstifeev AI, Welsh GI, Kotov NV. Kinetic regulation of multi-ligand binding proteins. BMC SYSTEMS BIOLOGY 2016; 10:32. [PMID: 27090530 PMCID: PMC4835871 DOI: 10.1186/s12918-016-0277-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 04/13/2016] [Indexed: 12/24/2022]
Abstract
BACKGROUND Second messengers, such as calcium, regulate the activity of multisite binding proteins in a concentration-dependent manner. For example, calcium binding has been shown to induce conformational transitions in the calcium-dependent protein calmodulin, under steady state conditions. However, intracellular concentrations of these second messengers are often subject to rapid change. The mechanisms underlying dynamic ligand-dependent regulation of multisite proteins require further elucidation. RESULTS In this study, a computational analysis of multisite protein kinetics in response to rapid changes in ligand concentrations is presented. Two major physiological scenarios are investigated: i) Ligand concentration is abundant and the ligand-multisite protein binding does not affect free ligand concentration, ii) Ligand concentration is of the same order of magnitude as the interacting multisite protein concentration and does not change. Therefore, buffering effects significantly influence the amounts of free ligands. For each of these scenarios the influence of the number of binding sites, the temporal effects on intermediate apo- and fully saturated conformations and the multisite regulatory effects on target proteins are investigated. CONCLUSIONS The developed models allow for a novel and accurate interpretation of concentration and pressure jump-dependent kinetic experiments. The presented model makes predictions for the temporal distribution of multisite protein conformations in complex with variable numbers of ligands. Furthermore, it derives the characteristic time and the dynamics for the kinetic responses elicited by a ligand concentration change as a function of ligand concentration and the number of ligand binding sites. Effector proteins regulated by multisite ligand binding are shown to depend on ligand concentration in a highly nonlinear fashion.
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Affiliation(s)
- Diana V. Salakhieva
- />Kazan (Volga Region) Federal University, 18 Kremlyovskaya St., 420008 Kazan, Russia
| | - Ildar I. Sadreev
- />Centre for Systems, Dynamics and Control, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Harrison Building, North Park Road, Exeter, EX4 4QF UK
| | - Michael Z. Q. Chen
- />Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Yoshinori Umezawa
- />Department of Dermatology, The Jikei University School of Medicine, 3-25-8 Nishishimbashi, Minato-ku, Tokyo, 105-8461 Japan
| | - Aleksandr I. Evstifeev
- />Biophysics & Bionics Lab, Institute of Physics, Kazan Federal University, Kazan, 420008 Russia
| | - Gavin I. Welsh
- />Academic Renal Unit, School of Clinical Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY UK
| | - Nikolay V. Kotov
- />Biophysics & Bionics Lab, Institute of Physics, Kazan Federal University, Kazan, 420008 Russia
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Garcia-Rill E, D’Onofrio S, Luster B, Mahaffey S, Urbano FJ, Phillips C. The 10 Hz Frequency: A Fulcrum For Transitional Brain States. TRANSLATIONAL BRAIN RHYTHMICITY 2016; 1:7-13. [PMID: 27547831 PMCID: PMC4990355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A 10 Hz rhythm is present in the occipital cortex when the eyes are closed (alpha waves), in the precentral cortex at rest (mu rhythm), in the superior and middle temporal lobe (tau rhythm), in the inferior olive (projection to cerebellar cortex), and in physiological tremor (underlying all voluntary movement). These are all considered resting rhythms in the waking brain which are "replaced" by higher frequency activity with sensorimotor stimulation. That is, the 10 Hz frequency fulcrum is replaced on the one hand by lower frequencies during sleep, or on the other hand by higher frequencies during volition and cognition. The 10 Hz frequency fulcrum is proposed as the natural frequency of the brain during quiet waking, but is replaced by higher frequencies capable of permitting more complex functions, or by lower frequencies during sleep and inactivity. At the center of the transition shifts to and from the resting rhythm is the reticular activating system, a phylogenetically preserved area of the brain essential for preconscious awareness.
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Affiliation(s)
- E. Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, US
| | - S. D’Onofrio
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, US
| | - B. Luster
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, US
| | - S. Mahaffey
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, US
| | - F. J. Urbano
- IFIBYNE-CONICET, University of Buenos Aires, Argentina
| | - C. Phillips
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, US
- Department of Physical Therapy, Arkansas State University, Jonesboro, AR, 72401
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Garcia-Rill E, Virmani T, Hyde J, D’Onofrio S, Mahaffey S. Arousal and the control of perception and movement. CURRENT TRENDS IN NEUROLOGY 2016; 10:53-64. [PMID: 28690375 PMCID: PMC5501251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Recent discoveries on the nature of the activity generated by the reticular activating system (RAS) suggest that arousal is much more involved in perception and movement than previously thought. The RAS is not simply an amorphous, unspecific region but rather a distinct group of nuclei with specific cell and transmitter types that control waking and modulate such processes as perception and movement. Thus, disturbances in the RAS will affect a number of neurological disorders. The discovery of gamma band activity in the RAS determined that high threshold calcium channels are responsible for generating gamma band activity in the RAS. Results showing that waking is mediated by CaMKII modulation of P/Q-type channels and REM sleep is modulated by cAMP/PK modulation of N-type channels points to different intracellular pathways influencing each state. Few studies address these important breakthroughs. Novel findings also show that the same primate RAS neurons exhibiting activity in relation to arousal are also involved in locomotion. Moreover, deep brain stimulation of this region, specifically the pedunculopontine nucleus (PPN DBS), in Parkinson's disease has salutary effects on movement, sleep, and cognition. Gamma oscillations appear to participate in sensory perception, problem solving, and memory, and coherence at these frequencies may occur at cortical or thalamocortical levels. However, rather than participating in the temporal binding of sensory events, gamma band activity generated in the RAS may help stabilize coherence related to arousal, providing a stable activation state during waking, and relay such activation to the cortex. Continuous sensory input will thus induce gamma band activity in the RAS to participate in the processes of preconscious awareness, and provide the essential stream of information for the formulation of many of our perceptions and actions. Such a role has received little attention but promises to help understand and treat a number of neurological disorders.
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Affiliation(s)
- E. Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR
| | - T. Virmani
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR
| | - J.R. Hyde
- Department of Psychiatry and Center for Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA
| | - S. D’Onofrio
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR
| | - S. Mahaffey
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR
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Pedunculopontine Gamma Band Activity and Development. Brain Sci 2015; 5:546-67. [PMID: 26633526 PMCID: PMC4701027 DOI: 10.3390/brainsci5040546] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 11/20/2015] [Accepted: 11/23/2015] [Indexed: 12/25/2022] Open
Abstract
This review highlights the most important discovery in the reticular activating system in the last 10 years, the manifestation of gamma band activity in cells of the reticular activating system (RAS), especially in the pedunculopontine nucleus, which is in charge of waking and rapid eye movement (REM) sleep. The identification of different cell groups manifesting P/Q-type Ca(2+) channels that control waking vs. those that manifest N-type channels that control REM sleep provides novel avenues for the differential control of waking vs. REM sleep. Recent discoveries on the development of this system can help explain the developmental decrease in REM sleep and the basic rest-activity cycle.
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Garcia-Rill E, Luster B, D’Onofrio S, Mahaffey S, Bisagno V, Urbano FJ. Pedunculopontine arousal system physiology - Deep brain stimulation (DBS). Sleep Sci 2015; 8:153-61. [PMID: 26779322 PMCID: PMC4688589 DOI: 10.1016/j.slsci.2015.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 09/03/2015] [Accepted: 09/05/2015] [Indexed: 12/19/2022] Open
Abstract
This review describes the wake/sleep symptoms present in Parkinson׳s disease, and the role of the pedunculopontine nucleus in these symptoms. The physiology of PPN cells is important not only because it is a major element of the reticular activating system, but also because it is a novel target for deep brain stimulation in the treatment of gait and postural deficits in Parkinson׳s disease. A greater understanding of the physiology of the target nuclei within the brainstem and basal ganglia, amassed over the past decades, has enabled increasingly better patient outcomes from deep brain stimulation for movement disorders.
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Key Words
- Basal forebrain
- Calcium channels
- DBS, deep brain stimulation
- EEG, electroencephalogram
- Gamma band activity
- LC, locus coeruleus
- Lateral hypothalamus
- Orexin
- PD, Parkinson׳s disease
- PGO, ponto-geniculo-occipital
- PPN, pedunculopontine nucleus
- RAS, reticular activating system
- REM, rapid eye movement
- SN, substantia nigra
- STN, subthalamic nucleus
- SubCD, subcoeruleus nucleus dorsalis
- Tuberomammillary
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Affiliation(s)
- Edgar Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Brennon Luster
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Stasia D’Onofrio
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Susan Mahaffey
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Veronica Bisagno
- IFIBYNE-CONICET and ININFA-CONICET, University of Buenos Aires, Argentina
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Garcia-Rill E, Luster B, D’Onofrio S, Mahaffey S. Arousal, motor control, and parkinson's disease. Transl Neurosci 2015; 6:198-207. [PMID: 27747095 PMCID: PMC4936629 DOI: 10.1515/tnsci-2015-0021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 08/30/2015] [Indexed: 11/22/2022] Open
Abstract
This review highlights the most important discovery in the reticular activating system (RAS) in the last 10 years, the manifestation of gamma (γ) band activity in cells of the RAS, especially in the pedunculopontine nucleus (PPN), which is in charge of the high frequency states of waking and rapid eye movement sleep. This discovery is critical to understanding the modulation of movement by the RAS and how it sets the background over which we generate voluntary and triggered movements. The presence of γ band activity in the RAS is proposed to participate in the process of preconscious awareness, and provide the essential stream of information for the formulation of many of our actions. Early findings using stimulation of this region to induce arousal, and also to elicit stepping, are placed in this context. This finding also helps explain the novel use of PPN deep brain stimulation for the treatment of Parkinson's disease, although considerable work remains to be done.
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Affiliation(s)
- E. Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - B. Luster
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - S. D’Onofrio
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - S. Mahaffey
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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24
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Luster B, D'Onofrio S, Urbano F, Garcia-Rill E. High-threshold Ca2+ channels behind gamma band activity in the pedunculopontine nucleus (PPN). Physiol Rep 2015; 3:3/6/e12431. [PMID: 26109189 PMCID: PMC4510632 DOI: 10.14814/phy2.12431] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The pedunculopontine nucleus (PPN) is part of the Reticular Activating System, and active during waking and REM sleep. Previous results showed that all PPN cells plateau at gamma frequencies and intrinsic membrane oscillations in PPN neurons are mediated by high-threshold N- and P/Q-type Ca2+ channels. The present study was designed to determine whether some PPN cells have only N-, only P/Q-, or both N- and P/Q-type Ca2+ channels. We used patch-clamp recordings in PPN cells in slices from anesthetized rat pups in the presence of synaptic receptor blockers (SB) and Tetrodotoxin (TTX), and applied ramps to induce intrinsic membrane oscillations. We found that all PPN cell types showed gamma oscillations in the presence of SB+TTX when using current ramps. In 50% of cells, the N-type Ca2+ channel blocker ω-Conotoxin-GVIA (ω-CgTx) reduced gamma oscillation amplitude, while subsequent addition of the P/Q-type blocker ω-Agatoxin-IVA (ω-Aga) blocked the remaining oscillations. Another 20% manifested gamma oscillations that were not significantly affected by the addition of ω-CgTx, however, ω-Aga blocked the remaining oscillations. In 30% of cells, ω-Aga had no effect on gamma oscillations, while ω-CgTx blocked them. These novel results confirm the segregation of populations of PPN cells as a function of the calcium channels expressed, that is, the presence of cells in the PPN that manifest gamma band oscillations through only N-type, only P/Q-type, and both N-type and P/Q-type Ca2+ channels.
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Affiliation(s)
- Brennon Luster
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Stasia D'Onofrio
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Francisco Urbano
- IFIBYNE-CONICET University of Buenos Aires, Buenos Aires, Argentina
| | - Edgar Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, Arkansas
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Ishibashi M, Gumenchuk I, Kang B, Steger C, Lynn E, Molina NE, Eisenberg LM, Leonard CS. Orexin Receptor Activation Generates Gamma Band Input to Cholinergic and Serotonergic Arousal System Neurons and Drives an Intrinsic Ca(2+)-Dependent Resonance in LDT and PPT Cholinergic Neurons. Front Neurol 2015; 6:120. [PMID: 26082752 PMCID: PMC4451588 DOI: 10.3389/fneur.2015.00120] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 05/11/2015] [Indexed: 01/29/2023] Open
Abstract
A hallmark of the waking state is a shift in EEG power to higher frequencies with epochs of synchronized intracortical gamma activity (30-60 Hz) - a process associated with high-level cognitive functions. The ascending arousal system, including cholinergic laterodorsal (LDT) and pedunculopontine (PPT) tegmental neurons and serotonergic dorsal raphe (DR) neurons, promotes this state. Recently, this system has been proposed as a gamma wave generator, in part, because some neurons produce high-threshold, Ca(2+)-dependent oscillations at gamma frequencies. However, it is not known whether arousal-related inputs to these neurons generate such oscillations, or whether such oscillations are ever transmitted to neuronal targets. Since key arousal input arises from hypothalamic orexin (hypocretin) neurons, we investigated whether the unusually noisy, depolarizing orexin current could provide significant gamma input to cholinergic and serotonergic neurons, and whether such input could drive Ca(2+)-dependent oscillations. Whole-cell recordings in brain slices were obtained from mice expressing Cre-induced fluorescence in cholinergic LDT and PPT, and serotonergic DR neurons. After first quantifying reporter expression accuracy in cholinergic and serotonergic neurons, we found that the orexin current produced significant high frequency, including gamma, input to both cholinergic and serotonergic neurons. Then, by using a dynamic clamp, we found that adding a noisy orexin conductance to cholinergic neurons induced a Ca(2+)-dependent resonance that peaked in the theta and alpha frequency range (4-14 Hz) and extended up to 100 Hz. We propose that this orexin current noise and the Ca(2+) dependent resonance work synergistically to boost the encoding of high-frequency synaptic inputs into action potentials and to help ensure cholinergic neurons fire during EEG activation. This activity could reinforce thalamocortical states supporting arousal, REM sleep, and intracortical gamma.
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Affiliation(s)
- Masaru Ishibashi
- Department of Physiology, New York Medical College , Valhalla, NY , USA
| | - Iryna Gumenchuk
- Department of Physiology, New York Medical College , Valhalla, NY , USA
| | - Bryan Kang
- Department of Physiology, New York Medical College , Valhalla, NY , USA
| | - Catherine Steger
- Department of Physiology, New York Medical College , Valhalla, NY , USA
| | - Elizabeth Lynn
- Department of Physiology, New York Medical College , Valhalla, NY , USA
| | - Nancy E Molina
- Department of Physiology, New York Medical College , Valhalla, NY , USA
| | - Leonard M Eisenberg
- Department of Physiology, New York Medical College , Valhalla, NY , USA ; Department of Medicine, New York Medical College , Valhalla, NY , USA
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Garcia-Rill E, D’Onofrio S, Mahaffey S, Bisagno V, Urbano FJ. Pedunculopontine arousal system physiology-Implications for schizophrenia. Sleep Sci 2015; 8:82-91. [PMID: 26483949 PMCID: PMC4608902 DOI: 10.1016/j.slsci.2015.04.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 04/23/2015] [Accepted: 04/30/2015] [Indexed: 01/24/2023] Open
Abstract
Schizophrenia is characterized by major sleep/wake disturbances including increased vigilance and arousal, decreased slow wave sleep, and increased REM sleep drive. Other arousal-related symptoms include sensory gating deficits as exemplified by decreased habituation of the blink reflex. There is also dysregulation of gamma band activity, suggestive of disturbances in a host of arousal-related mechanisms. This review examines the role of the reticular activating system, especially the pedunculopontine nucleus, in the symptoms of the disease. Recent discoveries on the physiology of the pedunculopontine nucleus help explain many of these disorders of arousal in, and point to novel therapeutic avenues for, schizophrenia.
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Key Words
- CaMKII, calcium/calmodulin-dependent protein kinase
- Calcium channels
- EEG, electroencephalogram
- EPSC, excitatory postsynaptic potential
- GABA, γ aminobutyric acid
- Gamma band activity
- InsP, inositol 1,4,5-triphosphate receptor protein
- KA, kainic acid
- NCS-1, neuronal calcium sensor protein 1
- NMDA, n methyl d aspartic acid
- Neuronal calcium sensor protein
- P50 potential
- PGO, ponto-geniculo-occipital
- PPN, pedunculopontine nucleus
- Pf, parafascicular nucleus
- RAS, reticular activating system
- REM, rapid eye movement
- SWS, slow wave sleep
- SubCD, subcoeruleus dorsalis
- cAMP, cyclic adenosine monophosphate
- ω-Aga, ω-agatoxin-IVA
- ω-CgTx, ω-conotoxin-GVIA
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Affiliation(s)
- Edgar Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Stasia D’Onofrio
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Susan Mahaffey
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Veronica Bisagno
- IFIBYNE-CONICET and ININFA-CONICET, University of Buenos Aires, Buenos Aires, Argentina
| | - Francisco J. Urbano
- IFIBYNE-CONICET and ININFA-CONICET, University of Buenos Aires, Buenos Aires, Argentina
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27
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Garcia-Rill E, Luster B, Mahaffey S, Bisagno V, Urbano FJ. Pedunculopontine arousal system physiology - Implications for insomnia. Sleep Sci 2015; 8:92-9. [PMID: 26483950 PMCID: PMC4608886 DOI: 10.1016/j.slsci.2015.06.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 06/08/2015] [Accepted: 06/12/2015] [Indexed: 01/09/2023] Open
Abstract
We consider insomnia a disorder of waking rather than a disorder of sleep. This review examines the role of the reticular activating system, especially the pedunculopontine nucleus, in the symptoms of insomnia, mainly representing an overactive waking drive. We determined that high frequency activity during waking and REM sleep is controlled by two different intracellular pathways and channel types in PPN cells. We found three different PPN cell types that have one or both channels and may be active during waking only, REM sleep only, or both. These discoveries point to a specific mechanism and novel therapeutic avenues for insomnia.
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Key Words
- CaMKII, calcium/calmodulin-dependent protein kinase
- Calcium channels
- EEG, electroencephalogram
- Gamma band activity
- KA, kainic acid
- N-type calcium channel
- NCS-1, neuronal calcium sensor protein 1
- NMDA, n methyl d aspartic acid
- Neuronal calcium sensor protein
- P/Q-type calcium channel
- PGO, ponto-geniculo-occipital
- PPN, pedunculopontine nucleus
- RAS, reticular activating system
- REM, rapid eye movement
- SWS, slow wave sleep
- cAMP, cyclic adenosine monophosphate
- ω-Aga, ω-agatoxin-IVA
- ω-CgTx, ω-conotoxin-GVIA
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Affiliation(s)
- Edgar Garcia-Rill
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Brennon Luster
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Susan Mahaffey
- Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Veronica Bisagno
- IFIBYNE-CONICET and ININFA-CONICET, University of Buenos Aires, Argentina
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28
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Garcia-Rill E, Hyde J, Kezunovic N, Urbano FJ, Petersen E. The physiology of the pedunculopontine nucleus: implications for deep brain stimulation. J Neural Transm (Vienna) 2015; 122:225-35. [PMID: 24880787 PMCID: PMC4484763 DOI: 10.1007/s00702-014-1243-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 05/09/2014] [Indexed: 01/07/2023]
Abstract
This brief review resolves a number of persistent conflicts regarding the location and characteristics of the mesencephalic locomotor region, which has in the past been described as not locomotion-specific and is more likely the pedunculopontine nucleus (PPN). The parameters of stimulation used to elicit changes in posture and locomotion we now know are ideally suited to match the intrinsic membrane properties of PPN neurons. The physiology of these cells is important not only because it is a major element of the reticular activating system, but also because it is a novel target for the treatment of gait and postural deficits in Parkinson's disease (PD). The discussion explains many of the effects reported following deep brain stimulation (DBS) of the PPN by different groups and provides guidelines for the determination of long-term assessment and effects of PPN DBS. A greater understanding of the physiology of the target nuclei within the brainstem and basal ganglia, amassed over the past decades, has enabled increasingly better patient outcomes from DBS for movement disorders. Despite these improvements, there remains a great opportunity for further understanding of the mechanisms through which DBS has its effects and for further development of appropriate technology to effect these treatments. We review the scientific basis for one of the newest targets, the PPN, in the treatment of PD and other movement disorders, and address the needs for further investigation.
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Affiliation(s)
- E Garcia-Rill
- Department of Neurobiology and Developmental Sciences, Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Slot 847, 4301 West Markham St, Little Rock, AR, 72205, USA,
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29
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D'Onofrio S, Kezunovic N, Hyde JR, Luster B, Messias E, Urbano FJ, Garcia-Rill E. Modulation of gamma oscillations in the pedunculopontine nucleus by neuronal calcium sensor protein-1: relevance to schizophrenia and bipolar disorder. J Neurophysiol 2014; 113:709-19. [PMID: 25376789 DOI: 10.1152/jn.00828.2014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Reduced levels of gamma-band activity are present in schizophrenia and bipolar disorder patients. In the same disorders, increased neuronal calcium sensor protein-1 (NCS-1) expression was reported in a series of postmortem studies. These disorders are also characterized by sleep dysregulation, suggesting a role for the reticular activating system (RAS). The discovery of gamma-band activity in the pedunculopontine nucleus (PPN), the cholinergic arm of the RAS, revealed that such activity was mediated by high-threshold calcium channels that are regulated by NCS-1. We hypothesized that NCS-1 normally regulates gamma-band oscillations through these calcium channels and that excessive levels of NCS-1, such as would be expected with overexpression, decrease gamma-band activity. We found that PPN neurons in rat brain slices manifested gamma-band oscillations that were increased by low levels of NCS-1 but suppressed by high levels of NCS-1. Our results suggest that NCS-1 overexpression may be responsible for the decrease in gamma-band activity present in at least some schizophrenia and bipolar disorder patients.
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Affiliation(s)
- Stasia D'Onofrio
- Center for Translational Neuroscience, Departments of Neurobiology and Developmental Sciences and Psychiatry, University of Arkansas for Medical Sciences, Little Rock, Arkansas; and
| | - Nebojsa Kezunovic
- Center for Translational Neuroscience, Departments of Neurobiology and Developmental Sciences and Psychiatry, University of Arkansas for Medical Sciences, Little Rock, Arkansas; and
| | - James R Hyde
- Center for Translational Neuroscience, Departments of Neurobiology and Developmental Sciences and Psychiatry, University of Arkansas for Medical Sciences, Little Rock, Arkansas; and
| | - Brennon Luster
- Center for Translational Neuroscience, Departments of Neurobiology and Developmental Sciences and Psychiatry, University of Arkansas for Medical Sciences, Little Rock, Arkansas; and
| | - Erick Messias
- Center for Translational Neuroscience, Departments of Neurobiology and Developmental Sciences and Psychiatry, University of Arkansas for Medical Sciences, Little Rock, Arkansas; and
| | - Francisco J Urbano
- Instituto de Fisiología, Biología Molecular y Neurociencias, Consejo Nacional de Investigaciones Científicas y Técnicas, University of Buenos Aires, Buenos Aires, Argentina
| | - Edgar Garcia-Rill
- Center for Translational Neuroscience, Departments of Neurobiology and Developmental Sciences and Psychiatry, University of Arkansas for Medical Sciences, Little Rock, Arkansas; and
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30
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Urbano FJ, D'Onofrio SM, Luster BR, Beck PB, Hyde JR, Bisagno V, Garcia-Rill E. Pedunculopontine Nucleus Gamma Band Activity-Preconscious Awareness, Waking, and REM Sleep. Front Neurol 2014; 5:210. [PMID: 25368599 PMCID: PMC4202729 DOI: 10.3389/fneur.2014.00210] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 10/01/2014] [Indexed: 11/13/2022] Open
Abstract
The pedunculopontine nucleus (PPN) is a major component of the reticular activating system (RAS) that regulates waking and REM sleep, states of high-frequency EEG activity. Recently, we described the presence of high threshold, voltage-dependent N- and P/Q-type calcium channels in RAS nuclei that subserve gamma band oscillations in the mesopontine PPN, intralaminar parafascicular nucleus (Pf), and pontine subcoeruleus nucleus dorsalis (SubCD). Cortical gamma band activity participates in sensory perception, problem solving, and memory. Rather than participating in the temporal binding of sensory events as in the cortex, gamma band activity in the RAS may participate in the processes of preconscious awareness, and provide the essential stream of information for the formulation of many of our actions. That is, the RAS may play an early permissive role in volition. Our latest results suggest that (1) the manifestation of gamma band activity during waking may employ a separate intracellular pathway compared to that during REM sleep, (2) neuronal calcium sensor (NCS-1) protein, which is over expressed in schizophrenia and bipolar disorder, modulates gamma band oscillations in the PPN in a concentration-dependent manner, (3) leptin, which undergoes resistance in obesity resulting in sleep dysregulation, decreases sodium currents in PPN neurons, accounting for its normal attenuation of waking, and (4) following our discovery of electrical coupling in the RAS, we hypothesize that there are cell clusters within the PPN that may act in concert. These results provide novel information on the mechanisms controlling high-frequency activity related to waking and REM sleep by elements of the RAS.
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Affiliation(s)
- Francisco J Urbano
- IFIBYNE & ININFA-CONICET, University of Buenos Aires , Buenos Aires , Argentina
| | - Stasia M D'Onofrio
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences , Little Rock, AR , USA
| | - Brennon R Luster
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences , Little Rock, AR , USA
| | - Paige B Beck
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences , Little Rock, AR , USA
| | - James Robert Hyde
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences , Little Rock, AR , USA
| | - Veronica Bisagno
- IFIBYNE & ININFA-CONICET, University of Buenos Aires , Buenos Aires , Argentina
| | - Edgar Garcia-Rill
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences , Little Rock, AR , USA
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31
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Garcia-Rill E, Kezunovic N, D'Onofrio S, Luster B, Hyde J, Bisagno V, Urbano FJ. Gamma band activity in the RAS-intracellular mechanisms. Exp Brain Res 2014; 232:1509-22. [PMID: 24309750 PMCID: PMC4013218 DOI: 10.1007/s00221-013-3794-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 11/21/2013] [Indexed: 11/29/2022]
Abstract
Gamma band activity participates in sensory perception, problem solving, and memory. This review considers recent evidence showing that cells in the reticular activating system (RAS) exhibit gamma band activity, and describes the intrinsic membrane properties behind such manifestation. Specifically, we discuss how cells in the mesopontine pedunculopontine nucleus, intralaminar parafascicular nucleus, and pontine SubCoeruleus nucleus dorsalis all fire in the gamma band range when maximally activated, but no higher. The mechanisms involve high-threshold, voltage-dependent P/Q-type calcium channels, or sodium-dependent subthreshold oscillations. Rather than participating in the temporal binding of sensory events as in the cortex, gamma band activity in the RAS may participate in the processes of preconscious awareness and provide the essential stream of information for the formulation of many of our actions. We address three necessary next steps resulting from these discoveries: an intracellular mechanism responsible for maintaining gamma band activity based on persistent G-protein activation, separate intracellular pathways that differentiate between gamma band activity during waking versus during REM sleep, and an intracellular mechanism responsible for the dysregulation in gamma band activity in schizophrenia. These findings open several promising research avenues that have not been thoroughly explored. What are the effects of sleep or REM sleep deprivation on these RAS mechanisms? Are these mechanisms involved in memory processing during waking and/or during REM sleep? Does gamma band processing differ during waking versus REM sleep after sleep or REM sleep deprivation?
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Affiliation(s)
- E Garcia-Rill
- Department of Neurobiology and Developmental Sciences, Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Slot 847, 4301 West Markham St., Little Rock, AR, 72205, USA,
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32
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Kezunovic N, Hyde J, Goitia B, Bisagno V, Urbano FJ, Garcia-Rill E. Muscarinic modulation of high frequency oscillations in pedunculopontine neurons. Front Neurol 2013; 4:176. [PMID: 24223570 PMCID: PMC3818577 DOI: 10.3389/fneur.2013.00176] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 10/22/2013] [Indexed: 11/13/2022] Open
Abstract
We previously reported that persistent application of the non-specific cholinergic agonist carbachol (CAR) increased the frequency of calcium channel-mediated oscillatory activity in pedunculopontine nucleus (PPN) neurons, which we identified as dependent on voltage-gated, high-threshold P/Q-type channels. Here, we tested the hypothesis that M2 muscarinic receptors and G-proteins associated with M2 receptors mediate the increase in oscillatory frequency in PPN neurons. We found, using depolarizing ramps, that patch clamped 9-12 day old rat PPN neurons (n = 189) reached their peak oscillatory activity around -20 mV membrane potential. Acute (short duration) application of CAR blocked the oscillatory activity through M2 muscarinic receptors, an effect blocked by atropine. However, persistent (long duration) application of CAR significantly increased the frequency of oscillatory activity in PPN neurons through M2 receptors [40 ± 1 Hz (with CAR) vs. 23 ± 1 Hz (without CAR); p < 0.001]. We then tested the effects of the G-protein antagonist guanosine 5'-[β-thio] diphosphate trilithium salt (GDP-β-S), and the G-protein agonist 5'-[γ-thio] triphosphate trilithium salt (GTP-γ-S). We found, using a three-step protocol in voltage-clamp mode, that the increase in the frequency of oscillations induced by M2 cholinergic receptors was linked to a voltage-dependent G-protein mechanism. In summary, these results suggest that persistent cholinergic input creates a permissive activation state in the PPN that allows high frequency P/Q-type calcium channel-mediated gamma oscillations to occur.
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Affiliation(s)
- Nebojsa Kezunovic
- Department of Neurobiology and Developmental Sciences, Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - James Hyde
- Department of Neurobiology and Developmental Sciences, Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Belen Goitia
- IFIBYNE-CONICET-UBA, University of Buenos Aires, Buenos Aires, Argentina
| | - Veronica Bisagno
- IFIBYNE-CONICET-UBA, University of Buenos Aires, Buenos Aires, Argentina
| | | | - Edgar Garcia-Rill
- Department of Neurobiology and Developmental Sciences, Center for Translational Neuroscience, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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