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Ricci A, Rubino E, Serra GP, Wallén-Mackenzie Å. Concerning neuromodulation as treatment of neurological and neuropsychiatric disorder: Insights gained from selective targeting of the subthalamic nucleus, para-subthalamic nucleus and zona incerta in rodents. Neuropharmacology 2024; 256:110003. [PMID: 38789078 DOI: 10.1016/j.neuropharm.2024.110003] [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: 02/06/2024] [Revised: 04/26/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024]
Abstract
Neuromodulation such as deep brain stimulation (DBS) is advancing as a clinical intervention in several neurological and neuropsychiatric disorders, including Parkinson's disease, dystonia, tremor, and obsessive-compulsive disorder (OCD) for which DBS is already applied to alleviate severely afflicted individuals of symptoms. Tourette syndrome and drug addiction are two additional disorders for which DBS is in trial or proposed as treatment. However, some major remaining obstacles prevent this intervention from reaching its full therapeutic potential. Side-effects have been reported, and not all DBS-treated individuals are relieved of their symptoms. One major target area for DBS electrodes is the subthalamic nucleus (STN) which plays important roles in motor, affective and associative functions, with impact on for example movement, motivation, impulsivity, compulsivity, as well as both reward and aversion. The multifunctionality of the STN is complex. Decoding the anatomical-functional organization of the STN could enhance strategic targeting in human patients. The STN is located in close proximity to zona incerta (ZI) and the para-subthalamic nucleus (pSTN). Together, the STN, pSTN and ZI form a highly heterogeneous and clinically important brain area. Rodent-based experimental studies, including opto- and chemogenetics as well as viral-genetic tract tracings, provide unique insight into complex neuronal circuitries and their impact on behavior with high spatial and temporal precision. This research field has advanced tremendously over the past few years. Here, we provide an inclusive review of current literature in the pre-clinical research fields centered around STN, pSTN and ZI in laboratory mice and rats; the three highly heterogeneous and enigmatic structures brought together in the context of relevance for treatment strategies. Specific emphasis is placed on methods of manipulation and behavioral impact.
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Affiliation(s)
- Alessia Ricci
- Uppsala University, Department of Organism Biology, 756 32 Uppsala, Sweden; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Eleonora Rubino
- Uppsala University, Department of Organism Biology, 756 32 Uppsala, Sweden; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Gian Pietro Serra
- Uppsala University, Department of Organism Biology, 756 32 Uppsala, Sweden; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Åsa Wallén-Mackenzie
- Uppsala University, Department of Organism Biology, 756 32 Uppsala, Sweden; Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA.
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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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3
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Prasad AA, Wallén-Mackenzie Å. Architecture of the subthalamic nucleus. Commun Biol 2024; 7:78. [PMID: 38200143 PMCID: PMC10782020 DOI: 10.1038/s42003-023-05691-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 12/11/2023] [Indexed: 01/12/2024] Open
Abstract
The subthalamic nucleus (STN) is a major neuromodulation target for the alleviation of neurological and neuropsychiatric symptoms using deep brain stimulation (DBS). STN-DBS is today applied as treatment in Parkinson´s disease, dystonia, essential tremor, and obsessive-compulsive disorder (OCD). STN-DBS also shows promise as a treatment for refractory Tourette syndrome. However, the internal organization of the STN has remained elusive and challenges researchers and clinicians: How can this small brain structure engage in the multitude of functions that renders it a key hub for therapeutic intervention of a variety of brain disorders ranging from motor to affective to cognitive? Based on recent gene expression studies of the STN, a comprehensive view of the anatomical and cellular organization, including revelations of spatio-molecular heterogeneity, is now possible to outline. In this review, we focus attention to the neurobiological architecture of the STN with specific emphasis on molecular patterns discovered within this complex brain area. Studies from human, non-human primate, and rodent brains now reveal anatomically defined distribution of specific molecular markers. Together their spatial patterns indicate a heterogeneous molecular architecture within the STN. Considering the translational capacity of targeting the STN in severe brain disorders, the addition of molecular profiling of the STN will allow for advancement in precision of clinical STN-based interventions.
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Affiliation(s)
- Asheeta A Prasad
- University of Sydney, School of Medical Sciences, Faculty of Medicine and Health, Sydney, NSW, Australia.
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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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5
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Dautan D, Kovács A, Bayasgalan T, Diaz-Acevedo MA, Pal B, Mena-Segovia J. Modulation of motor behavior by the mesencephalic locomotor region. Cell Rep 2021; 36:109594. [PMID: 34433068 PMCID: PMC8641693 DOI: 10.1016/j.celrep.2021.109594] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 05/05/2021] [Accepted: 08/02/2021] [Indexed: 11/09/2022] Open
Abstract
The mesencephalic locomotor region (MLR) serves as an interface between higher-order motor systems and lower motor neurons. The excitatory module of the MLR is composed of the pedunculopontine nucleus (PPN) and the cuneiform nucleus (CnF), and their activation has been proposed to elicit different modalities of movement. However, how the differences in connectivity and physiological properties explain their contributions to motor activity is not well known. Here we report that CnF glutamatergic neurons are more electrophysiologically homogeneous than PPN neurons and have mostly short-range connectivity, whereas PPN glutamatergic neurons are heterogeneous and maintain long-range connections, most notably with the basal ganglia. Optogenetic activation of CnF neurons produces short-lasting muscle activation, driving involuntary motor activity. In contrast, PPN neuron activation produces long-lasting increases in muscle tone that reduce motor activity and disrupt gait. Our results highlight biophysical and functional attributes among MLR neurons that support their differential contribution to motor behavior. Dautan et al. show key differences in the connectivity and physiological properties of neurons of the mesencephalic locomotor region. Although activation of CnF neurons elicits involuntary locomotor responses, activation of PPN neurons increases muscle tone and reduces motor activity, suggesting that PPN encodes a readiness signal that precedes locomotion.
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Affiliation(s)
- Daniel Dautan
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ 07102, USA.
| | - Adrienn Kovács
- Department of Physiology, University of Debrecen, Faculty of Medicine, 4012 Debrecen, Hungary
| | - Tsogbadrakh Bayasgalan
- Department of Physiology, University of Debrecen, Faculty of Medicine, 4012 Debrecen, Hungary
| | - Miguel A Diaz-Acevedo
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ 07102, USA
| | - Balazs Pal
- Department of Physiology, University of Debrecen, Faculty of Medicine, 4012 Debrecen, Hungary
| | - Juan Mena-Segovia
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ 07102, USA.
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6
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Tau-driven degeneration of sleep- and wake-regulating neurons in Alzheimer's disease. Sleep Med Rev 2021; 60:101541. [PMID: 34500400 DOI: 10.1016/j.smrv.2021.101541] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 07/22/2021] [Accepted: 08/06/2021] [Indexed: 11/22/2022]
Abstract
Disturbances of the sleep/wake cycle in Alzheimer's disease (AD) are common, frequently precede cognitive decline, and tend to worsen with disease progression. Sleep is critical to the maintenance of homeostatic and circadian function, and chronic sleep disturbances have significant cognitive and physical health consequences that likely exacerbate disease severity. Sleep-wake cycles are regulated by neuromodulatory centers located in the brainstem, the hypothalamus, and the basal forebrain, many of which are vulnerable to the accumulation of abnormal protein deposits associated with neurodegenerative conditions. In AD, while sleep disturbances are commonly attributed to the accumulation of amyloid beta, patients often first experience sleep issues prior to the appearance of amyloid beta plaques, on a timeline that more closely corresponds to the first appearance of abnormal tau neurofibrillary tangles in sleep/wake regulating areas of the brainstem. Sleep disturbances also occur in pure tauopathies, providing further support that tau is a major contributor. Here, we provide an overview of the neuroanatomy of sleep/wake centers discovered in animal models, and review the evidence that tau-driven neuropathology is a primary driver of sleep disturbance in AD.
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Vitale F, Capozzo A, Mazzone P, Scarnati E. Neurophysiology of the pedunculopontine tegmental nucleus. Neurobiol Dis 2019. [DOI: 10.1016/j.nbd.2018.03.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Baksa B, Kovács A, Bayasgalan T, Szentesi P, Kőszeghy Á, Szücs P, Pál B. Characterization of functional subgroups among genetically identified cholinergic neurons in the pedunculopontine nucleus. Cell Mol Life Sci 2019; 76:2799-2815. [PMID: 30734834 PMCID: PMC6588655 DOI: 10.1007/s00018-019-03025-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 12/21/2018] [Accepted: 01/23/2019] [Indexed: 12/19/2022]
Abstract
The pedunculopontine nucleus (PPN) is a part of the reticular activating system which is composed of cholinergic, glutamatergic and GABAergic neurons. Early electrophysiological studies characterized and grouped PPN neurons based on certain functional properties (i.e., the presence or absence of the A-current, spike latency, and low threshold spikes). Although other electrophysiological characteristics of these neurons were also described (as high threshold membrane potential oscillations, great differences in spontaneous firing rate and the presence or absence of the M-current), systematic assessment of these properties and correlation of them with morphological markers are still missing. In this work, we conducted electrophysiological experiments on brain slices of genetically identified cholinergic neurons in the PPN. Electrophysiological properties were compared with rostrocaudal location of the neuronal soma and selected morphometric features obtained with post hoc reconstruction. We found that functional subgroups had different proportions in the rostral and caudal subregions of the nucleus. Neurons with A-current can be divided to early-firing and late-firing neurons, where the latter type was found exclusively in the caudal subregion. Similar to this, different parameters of high threshold membrane potential oscillations also showed characteristic rostrocaudal distribution. Furthermore, based on our data, we propose that high threshold oscillations rather emerge from neuronal somata and not from the proximal dendrites. In summary, we demonstrated the existence and spatial distribution of functional subgroups of genetically identified PPN cholinergic neurons, which are in accordance with differences found in projection and in vivo functional findings of the subregions. Being aware of functional differences of PPN subregions will help the design and analysis of experiments using genetically encoded opto- and chemogenetic markers for in vivo experiments.
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Affiliation(s)
- B Baksa
- Department of Physiology, University of Debrecen, Faculty of Medicine, Nagyerdei krt 98, Debrecen, 4012, Hungary
| | - A Kovács
- Department of Physiology, University of Debrecen, Faculty of Medicine, Nagyerdei krt 98, Debrecen, 4012, Hungary
| | - T Bayasgalan
- Department of Physiology, University of Debrecen, Faculty of Medicine, Nagyerdei krt 98, Debrecen, 4012, Hungary
| | - P Szentesi
- Department of Physiology, University of Debrecen, Faculty of Medicine, Nagyerdei krt 98, Debrecen, 4012, Hungary
| | - Á Kőszeghy
- Department of Physiology, University of Debrecen, Faculty of Medicine, Nagyerdei krt 98, Debrecen, 4012, Hungary
- Division of Cognitive Neurobiology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - P Szücs
- Department of Anatomy, Histology and Embriology, University of Debrecen, Faculty of Medicine, Debrecen, Hungary
| | - Balázs Pál
- Department of Physiology, University of Debrecen, Faculty of Medicine, Nagyerdei krt 98, Debrecen, 4012, Hungary.
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Tiroshi L, Goldberg JA. Population dynamics and entrainment of basal ganglia pacemakers are shaped by their dendritic arbors. PLoS Comput Biol 2019; 15:e1006782. [PMID: 30730886 PMCID: PMC6382172 DOI: 10.1371/journal.pcbi.1006782] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 02/20/2019] [Accepted: 01/10/2019] [Indexed: 11/30/2022] Open
Abstract
The theory of phase oscillators is an essential tool for understanding population dynamics of pacemaking neurons. GABAergic pacemakers in the substantia nigra pars reticulata (SNr), a main basal ganglia (BG) output nucleus, receive inputs from the direct and indirect pathways at distal and proximal regions of their dendritic arbors, respectively. We combine theory, optogenetic stimulation and electrophysiological experiments in acute brain slices to ask how dendritic properties impact the propensity of the various inputs, arriving at different locations along the dendrite, to recruit or entrain SNr pacemakers. By combining cable theory with sinusoidally-modulated optogenetic activation of either proximal somatodendritic regions or the entire somatodendritic arbor of SNr neurons, we construct an analytical model that accurately fits the empirically measured somatic current response to inputs arising from illuminating the soma and various portions of the dendritic field. We show that the extent of the dendritic tree that is illuminated generates measurable and systematic differences in the pacemaker’s phase response curve (PRC), causing a shift in its peak. Finally, we show that the divergent PRCs correctly predict differences in two major features of the collective dynamics of SNr neurons: the fidelity of population responses to sudden step-like changes in inputs; and the phase latency at which SNr neurons are entrained by rhythmic stimulation, which can occur in the BG under both physiological and pathophysiological conditions. Our novel method generates measurable and physiologically meaningful spatial effects, and provides the first empirical demonstration of how the collective responses of SNr pacemakers are determined by the transmission properties of their dendrites. SNr dendrites may serve to delay distal striatal inputs so that they impinge on the spike initiation zone simultaneously with pallidal and subthalamic inputs in order to guarantee a fair competition between the influence of the monosynaptic direct- and polysynaptic indirect pathways. The substantia nigra pars reticulata (SNr) is a main output nucleus of the basal ganglia (BG), where inputs from the competing direct and indirect pathways converge onto the same neurons. Interestingly, these inputs are differentially distributed with direct and indirect pathway projections arriving at distal and proximal regions of the dendritic arbor, respectively. We employ a novel method combining theory with electrophysiological experiments and optogenetics to study the distinct effects of inputs arriving at different locations along the dendrite. Our approach represents a useful compromise between complexity and reduction in modelling. Our work addresses the question of high fidelity encoding of inputs by networks of neurons in the new context of pacemaking neurons, which are driven to fire by their intrinsic dynamics rather than by a network state. We provide the first empirical demonstration that dendritic delays can introduce latencies in the responses of a population of neurons that are commensurate with synaptic delays, suggesting a new role for SNr dendrites with implications for BG function.
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Affiliation(s)
- Lior Tiroshi
- Department of Medical Neurobiology, Institute of Medical Research Israel–Canada, The Faculty of Medicine, Jerusalem, Israel
- Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Joshua A. Goldberg
- Department of Medical Neurobiology, Institute of Medical Research Israel–Canada, The Faculty of Medicine, Jerusalem, Israel
- * E-mail:
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Di Giovanni G, Chagraoui A, Puginier E, Galati S, De Deurwaerdère P. Reciprocal interaction between monoaminergic systems and the pedunculopontine nucleus: Implication in the mechanism of L-DOPA. Neurobiol Dis 2018; 128:9-18. [PMID: 30149181 DOI: 10.1016/j.nbd.2018.08.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 07/19/2018] [Accepted: 08/23/2018] [Indexed: 01/31/2023] Open
Abstract
The pedunculopontine nucleus (PPN) is part of the mesencephalic locomotor region (MLR) and has been involved in the control of gait, posture, locomotion, sleep, and arousal. It likely participates in some motor and non-motor symptoms of Parkinson's disease and is regularly proposed as a surgical target to ameliorate gait, posture and sleep disorders in Parkinsonian patients. The PPN overlaps with the monoaminergic systems including dopamine, serotonin and noradrenaline in the modulation of the above-mentioned functions. All these systems are involved in Parkinson's disease and the mechanism of the anti-Parkinsonian agents, mostly L-DOPA. This suggests that PPN interacts with monoaminergic neurons and vice versa. Some evidence indicates that the PPN sends cholinergic, glutamatergic and even gabaergic inputs to mesencephalic dopaminergic cells, with the data regarding serotonergic or noradrenergic cells being less well known. Similarly, the control exerted by the PPN on dopaminergic neurons, is multiple and complex, and more extensively explored than the other monoaminergic systems. The data on the influence of monoaminergic systems on PPN neuron activity are rather scarce. While there is evidence that the PPN influences the therapeutic response of L-DOPA, it is still difficult to discerne the reciprocal action of the PPN and monoaminergic systems in this action. Additional data are required to better understand the functional organization of monoaminergic inputs to the MLR including the PPN to get a clearer picture of their interaction.
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Affiliation(s)
- Giuseppe Di Giovanni
- Department of Physiology & Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Neuroscience Division, School of Biosciences, Cardiff University, Cardiff, UK.
| | - Abdeslam Chagraoui
- Normandie Univ, UNIROUEN, INSERM, U1239, CHU Rouen, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Institute for Research and Innovation in Biomedicine of Normandy (IRIB), Rouen, France; Department of Medical Biochemistry, Rouen University Hospital, Rouen, France
| | - Emilie Puginier
- Normandie Univ, UNIROUEN, INSERM, U1239, CHU Rouen, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Institute for Research and Innovation in Biomedicine of Normandy (IRIB), Rouen, France; Department of Medical Biochemistry, Rouen University Hospital, Rouen, France
| | - Salvatore Galati
- Parkinson and movement Disorders Center Neurocenter of Southern Switzerland, Ospedale Civico di Lugano, Lugano, Switzerland
| | - Philippe De Deurwaerdère
- Centre National de la Recherche Scientifique (Unité Mixte de Recherche 5287), 146 rue Léo Saignat, B.P.281, F-33000 Bordeaux Cedex, France.
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Parallel descending dopaminergic connectivity of A13 cells to the brainstem locomotor centers. Sci Rep 2018; 8:7972. [PMID: 29789702 PMCID: PMC5964077 DOI: 10.1038/s41598-018-25908-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 04/30/2018] [Indexed: 12/20/2022] Open
Abstract
The mesencephalic locomotor region (MLR) is an important integrative area for the initiation and modulation of locomotion. Recently it has been realized that dopamine (DA) projections from the substantia nigra pars compacta project to the MLR. Here we explore DA projections from an area of the medial zona incerta (ZI) known for its role in motor control onto the MLR. We provide evidence that dopaminergic (DAergic) A13 neurons have connectivity to the cuneiform nucleus (CnF) and pedunculopontine tegmental nucleus (PPTg) of the MLR. No ascending connectivity to the dorsolateral striatum was observed. On the other hand, DAergic A13 projections to the medullary reticular formation (MRF) and the lumbar spinal cord were sparse. A small number of non-DAergic neurons within the medial ZI projected to the lumbar spinal cord. We then characterized the DA A13 cells and report that these cells differ from canonical DA neurons since they lack the Dopamine Transporter (DAT). The lack of DAT expression, and possibly the lack of a dopamine reuptake mechanism, points to a longer time of action compared to typical dopamine neurons. Collectively our data suggest a parallel descending DAergic pathway from the A13 neurons of the medial ZI to the MLR, which we expect is important for modulating movement.
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Direct and indirect nigrofugal projections to the nucleus reticularis pontis caudalis mediate in the motor execution of the acoustic startle reflex. Brain Struct Funct 2018; 223:2733-2751. [DOI: 10.1007/s00429-018-1654-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 03/17/2018] [Indexed: 11/25/2022]
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13
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Roseberry T, Kreitzer A. Neural circuitry for behavioural arrest. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2016.0197. [PMID: 28242731 DOI: 10.1098/rstb.2016.0197] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2016] [Indexed: 11/12/2022] Open
Abstract
The ability to stop ongoing movement is fundamental to animal survival. Behavioural arrest involves the hierarchical integration of information throughout the forebrain, which ultimately leads to the coordinated inhibition and activation of specific brainstem motor centres. Recent advances have shed light on multiple regions and pathways involved in this critical behavioural process. Here, we synthesize these new findings together with previous work to build a more complete understanding of the circuit mechanisms underlying suppression of ongoing action. We focus on three specific conditions leading to behavioural arrest: goal completion, fear and startle. We outline the circuitry responsible for the production of these behaviours and discuss their dysfunction in neurological disease.This article is part of the themed issue 'Movement suppression: brain mechanisms for stopping and stillness'.
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Affiliation(s)
- Thomas Roseberry
- The Gladstone Institutes, San Francisco, CA 94158, USA.,Neuroscience Graduate Program, University of California, San Francisco, CA 94158, USA
| | - Anatol Kreitzer
- The Gladstone Institutes, San Francisco, CA 94158, USA .,Neuroscience Graduate Program, University of California, San Francisco, CA 94158, USA.,Departments of Physiology and Neurology, University of California, San Francisco, CA 94158, USA.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA 94158, USA
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On the Role of the Pedunculopontine Nucleus and Mesencephalic Reticular Formation in Locomotion in Nonhuman Primates. J Neurosci 2017; 36:4917-29. [PMID: 27147647 DOI: 10.1523/jneurosci.2514-15.2016] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 02/22/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED The mesencephalic reticular formation (MRF) is formed by the pedunculopontine and cuneiform nuclei, two neuronal structures thought to be key elements in the supraspinal control of locomotion, muscle tone, waking, and REM sleep. The role of MRF has also been advocated in modulation of state of arousal leading to transition from wakefulness to sleep and it is further considered to be a main player in the pathophysiology of gait disorders seen in Parkinson's disease. However, the existence of a mesencephalic locomotor region and of an arousal center has not yet been demonstrated in primates. Here, we provide the first extensive electrophysiological mapping of the MRF using extracellular recordings at rest and during locomotion in a nonhuman primate (NHP) (Macaca fascicularis) model of bipedal locomotion. We found different neuronal populations that discharged according to a phasic or a tonic mode in response to locomotion, supporting the existence of a locomotor neuronal circuit within these MRF in behaving primates. Altogether, these data constitute the first electrophysiological characterization of a locomotor neuronal system present within the MRF in behaving NHPs under normal conditions, in accordance with several studies done in different experimental animal models. SIGNIFICANCE STATEMENT We provide the first extensive electrophysiological mapping of the two major components of the mesencephalic reticular formation (MRF), namely the pedunculopontine and cuneiform nuclei. We exploited a nonhuman primate (NHP) model of bipedal locomotion with extracellular recordings in behaving NHPs at rest and during locomotion. Different MRF neuronal groups were found to respond to locomotion, with phasic or tonic patterns of response. These data constitute the first electrophysiological evidences of a locomotor neuronal system within the MRF in behaving NHPs.
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Surmeier DJ, Halliday GM, Simuni T. Calcium, mitochondrial dysfunction and slowing the progression of Parkinson's disease. Exp Neurol 2017; 298:202-209. [PMID: 28780195 DOI: 10.1016/j.expneurol.2017.08.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 07/25/2017] [Accepted: 08/01/2017] [Indexed: 12/20/2022]
Abstract
Parkinson's disease is characterized by progressively distributed Lewy pathology and neurodegeneration. The motor symptoms of clinical Parkinson's disease (cPD) are unequivocally linked to the degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc). Several features of these neurons appear to make them selectively vulnerable to factors thought to cause cPD, like aging, genetic mutations and environmental toxins. Among these features, Ca2+ entry through Cav1 channels is particularly amenable to pharmacotherapy in early stage cPD patients. This review outlines the linkage between these channels, mitochondrial oxidant stress and cPD pathogenesis. It also summarizes considerations that went into the design and execution of the ongoing Phase 3 clinical trial with an inhibitor of these channels - isradipine.
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Affiliation(s)
- D James Surmeier
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Glenda M Halliday
- Brain and Mind Centre, Sydney Medical School, University of Sydney, 2006, Australia; School of Medical Sciences, University of New South Wales, Neuroscience Research Australia, Sydney 2052, Australia
| | - Tanya Simuni
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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16
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Surmeier DJ, Obeso JA, Halliday GM. Selective neuronal vulnerability in Parkinson disease. Nat Rev Neurosci 2017; 18:101-113. [PMID: 28104909 DOI: 10.1038/nrn.2016.178] [Citation(s) in RCA: 623] [Impact Index Per Article: 89.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Intracellular α-synuclein (α-syn)-rich protein aggregates called Lewy pathology (LP) and neuronal death are commonly found in the brains of patients with clinical Parkinson disease (cPD). It is widely believed that LP appears early in the disease and spreads in synaptically coupled brain networks, driving neuronal dysfunction and death. However, post-mortem analysis of human brains and connectome-mapping studies show that the pattern of LP in cPD is not consistent with this simple model, arguing that, if LP propagates in cPD, it must be gated by cell- or region-autonomous mechanisms. Moreover, the correlation between LP and neuronal death is weak. In this Review, we briefly discuss the evidence for and against the spreading LP model, as well as evidence that cell-autonomous factors govern both α-syn pathology and neuronal death.
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Affiliation(s)
- D James Surmeier
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | - José A Obeso
- Centro Integral de Neurociencias A.C. (CINAC), HM Puerta del Sur, Hospitales de Madrid, Mostoles and CEU San Pablo University, 28938 Madrid, Spain.,Network Center for Biomedical Research on Neurodegenerative Diseases (CIBERNED), Instituto Carlos III, 28031 Madrid, Spain
| | - Glenda M Halliday
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, Sydney 2006, Australia.,School of Medical Sciences, University of New South Wales and Neuroscience Research Australia, Sydney 2052, Australia
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17
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Effects of bilateral vestibular deafferentation in rat on hippocampal theta response to somatosensory stimulation, acetylcholine release, and cholinergic neurons in the pedunculopontine tegmental nucleus. Brain Struct Funct 2017; 222:3319-3332. [PMID: 28349227 DOI: 10.1007/s00429-017-1407-1] [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: 12/11/2016] [Accepted: 03/14/2017] [Indexed: 12/18/2022]
Abstract
Vestibular dysfunction has been shown to cause spatial memory impairment. Neurophysiological studies indicate that bilateral vestibular loss (BVL), in particular, is associated with an impairment of the response of hippocampal place cells and theta rhythm. However, the specific neural pathways through which vestibular information reaches the hippocampus are yet to be fully elucidated. The aim of the present study was to further investigate the hypothesised 'theta-generating pathway' from the brainstem vestibular nucleus to the hippocampus. BVL, and in some cases, unilateral vestibular loss (UVL), induced by intratympanic sodium arsanilate injections in rats, were used to investigate the effects of vestibular loss on somatosensory-induced type 2 theta rhythm, acetylcholine (ACh) release in the hippocampus, and the number of cholinergic neurons in the pedunculopontine tegmental nucleus (PPTg), an important part of the theta-generating pathway. Under urethane anaesthesia, BVL was found to cause a significant increase in the maximum power of the type 2 theta (3-6 Hz) frequency band compared to UVL and sham animals. Rats with BVL generally exhibited a lower basal level of ACh release than sham rats; however, this difference was not statistically significant. The PPTg of BVL rats exhibited significantly more choline-acetyltransferase (ChAT)-positive neurons than that of sham animals, as did the contralateral PPTg of UVL animals; however, the number of ChAT-positive neurons on the ipsilateral side of UVL animals was not significantly different from sham animals. The results of these studies indicate that parts of the theta-generating pathway undergo a significant reorganisation following vestibular loss, which suggests that this pathway is important for the interaction between the vestibular system and the hippocampus.
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18
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Alho ATDL, Hamani C, Alho EJL, da Silva RE, Santos GAB, Neves RC, Carreira LL, Araújo CMM, Magalhães G, Coelho DB, Alegro MC, Martin MGM, Grinberg LT, Pasqualucci CA, Heinsen H, Fonoff ET, Amaro E. Magnetic resonance diffusion tensor imaging for the pedunculopontine nucleus: proof of concept and histological correlation. Brain Struct Funct 2017; 222:2547-2558. [PMID: 28283747 DOI: 10.1007/s00429-016-1356-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 12/19/2016] [Indexed: 12/18/2022]
Abstract
The pedunculopontine nucleus (PPN) has been proposed as target for deep brain stimulation (DBS) in patients with postural instability and gait disorders due to its involvement in muscle tonus adjustments and control of locomotion. However, it is a deep-seated brainstem nucleus without clear imaging or electrophysiological markers. Some studies suggested that diffusion tensor imaging (DTI) may help guiding electrode placement in the PPN by showing the surrounding fiber bundles, but none have provided a direct histological correlation. We investigated DTI fractional anisotropy (FA) maps from in vivo and in situ post-mortem magnetic resonance images (MRI) compared to histological evaluations for improving PPN targeting in humans. A post-mortem brain was scanned in a clinical 3T MR system in situ. Thereafter, the brain was processed with a special method ideally suited for cytoarchitectonic analyses. Also, nine volunteers had in vivo brain scanning using the same MRI protocol. Images from volunteers were compared to those obtained in the post-mortem study. FA values of the volunteers were obtained from PPN, inferior colliculus, cerebellar crossing fibers and medial lemniscus using histological data and atlas information. FA values in the PPN were significantly lower than in the surrounding white matter region and higher than in areas with predominantly gray matter. In Nissl-stained histologic sections, the PPN extended for more than 10 mm in the rostro-caudal axis being closely attached to the lateral parabrachial nucleus. Our DTI analyses and the spatial correlation with histological findings proposed a location for PPN that matched the position assigned to this nucleus in the literature. Coregistration of neuroimaging and cytoarchitectonic features can add value to help establishing functional architectonics of the PPN and facilitate neurosurgical targeting of this extended nucleus.
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Affiliation(s)
- A T D L Alho
- Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, Brazil.,Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.,Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - C Hamani
- Division of Neurosurgery, Toronto Western Hospital, University of Toronto, Centre for Addiction and Mental Health, Toronto, Canada
| | - E J L Alho
- Department of Neurology Faculdade de Medicina da Universidade de São Paulo, Divisão de Neurocirurgia Funcional do, Instituto de Psiquiatria-HCFMUSP, São Paulo, Brazil
| | - R E da Silva
- Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil
| | - G A B Santos
- Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil
| | - R C Neves
- Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - L L Carreira
- Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil
| | - C M M Araújo
- Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.,Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - G Magalhães
- Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, Brazil.,Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.,Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - D B Coelho
- Escola de Educação Física e Esporte da Universidade de São Paulo, São Paulo, Brazil
| | - M C Alegro
- Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, Brazil.,Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.,Memory and Aging Center, Department of Neurology, University of California, San Francisco, USA
| | - M G M Martin
- Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil
| | - L T Grinberg
- Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.,Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.,Memory and Aging Center, Department of Neurology, University of California, San Francisco, USA
| | - C A Pasqualucci
- Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.,Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - H Heinsen
- Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.,Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.,Department of Psychiatry, Psychiatric Clinic, Julius-Maximilians-University Würzburg, Universitätsklinikum Würzburg, Würzburg, Germany
| | - E T Fonoff
- Department of Neurology Faculdade de Medicina da Universidade de São Paulo, Divisão de Neurocirurgia Funcional do, Instituto de Psiquiatria-HCFMUSP, São Paulo, Brazil.
| | - E Amaro
- Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, Brazil.,Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil
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19
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Mori F, Okada KI, Nomura T, Kobayashi Y. The Pedunculopontine Tegmental Nucleus as a Motor and Cognitive Interface between the Cerebellum and Basal Ganglia. Front Neuroanat 2016; 10:109. [PMID: 27872585 PMCID: PMC5097925 DOI: 10.3389/fnana.2016.00109] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/24/2016] [Indexed: 11/13/2022] Open
Abstract
As an important component of ascending activating systems, brainstem cholinergic neurons in the pedunculopontine tegmental nucleus (PPTg) are involved in the regulation of motor control (locomotion, posture and gaze) and cognitive processes (attention, learning and memory). The PPTg is highly interconnected with several regions of the basal ganglia, and one of its key functions is to regulate and relay activity from the basal ganglia. Together, they have been implicated in the motor control system (such as voluntary movement initiation or inhibition), and modulate aspects of executive function (such as motivation). In addition to its intimate connection with the basal ganglia, projections from the PPTg to the cerebellum have been recently reported to synaptically activate the deep cerebellar nuclei. Classically, the cerebellum and basal ganglia were regarded as forming separated anatomical loops that play a distinct functional role in motor and cognitive behavioral control. Here, we suggest that the PPTg may also act as an interface device between the basal ganglia and cerebellum. As such, part of the therapeutic effect of PPTg deep brain stimulation (DBS) to relieve gait freezing and postural instability in advanced Parkinson’s disease (PD) patients might also involve modulation of the cerebellum. We review the anatomical position and role of the PPTg in the pathway of basal ganglia and cerebellum in relation to motor control, cognitive function and PD.
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Affiliation(s)
- Fumika Mori
- Laboratories for Neuroscience Visual Neuroscience Group, Graduate School of Frontier Biosciences, Osaka UniversityOsaka, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology and Osaka UniversityOsaka, Japan
| | - Ken-Ichi Okada
- Laboratories for Neuroscience Visual Neuroscience Group, Graduate School of Frontier Biosciences, Osaka UniversityOsaka, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology and Osaka UniversityOsaka, Japan
| | - Taishin Nomura
- Bio-Dynamics Group, Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University Osaka, Japan
| | - Yasushi Kobayashi
- Laboratories for Neuroscience Visual Neuroscience Group, Graduate School of Frontier Biosciences, Osaka UniversityOsaka, Japan; Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology and Osaka UniversityOsaka, Japan; Research Center for Behavioral Economics, Osaka UniversityOsaka, Japan
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20
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Veleanu M, Axen TE, Kristensen MP, Kohlmeier KA. Comparison of bNOS and chat immunohistochemistry in the laterodorsal tegmentum (LDT) and the pedunculopontine tegmentum (PPT) of the mouse from brain slices prepared for electrophysiology. J Neurosci Methods 2016; 263:23-35. [DOI: 10.1016/j.jneumeth.2016.01.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 12/30/2015] [Accepted: 01/18/2016] [Indexed: 01/16/2023]
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21
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Sitti I, Acar G, Zisakis AK, Özdemir M, Acar F, Burchiel KJ. Effect of Subthalamic Nucleus Stimulation on Pedunculopontine Nucleus Neural Activity. Stereotact Funct Neurosurg 2016; 94:54-9. [PMID: 26977617 DOI: 10.1159/000442892] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 11/30/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND The pedunculopontine nucleus has recently been proposed as an alternative target for deep brain stimulation for the treatment of medically intractable Parkinson's disease. The suggested indication for pedunculopontine nucleus deep brain stimulation is severe and medically intractable axial symptoms such as gait and postural impairment. OBJECTIVE Our goal in this study was to describe the effects of subthalamic nucleus stimulation on pedunculopontine nucleus electrophysiological activity. METHODS Fourteen male Wistar rats were divided into a sham stimulation group and an experimental group. In both groups, electrodes were implanted bilaterally into the subthalamic nucleus and into the right pedunculopontine nucleus. Microelectrode recordings were carried out in both groups prior to and during subthalamic nucleus stimulation. RESULTS Subthalamic nucleus stimulation produced no clear inhibition of neuronal firing in the pedunculopontine nucleus. However, we found that stimulation of the subthalamic nucleus at 60 Hz produces some entrainment of pedunculopontine nucleus neuronal firing and a shift of subthalamic nucleus firing patterns to more tonic and random patterns. These results are consistent with the effects of deep brain stimulation on neuronal activity in the subthalamic nucleus and globus pallidus internus. CONCLUSION The result of this study provides additional evidence to improve our understanding of the mechanism of subthalamic nucleus-deep brain stimulation, and its physiological consequences.
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Affiliation(s)
- Ilkay Sitti
- Department of Neurosurgery, Faculty of Medicine, Pamukkale University, Denizli, Turkey
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22
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Pienaar IS, Gartside SE, Sharma P, De Paola V, Gretenkord S, Withers D, Elson JL, Dexter DT. Pharmacogenetic stimulation of cholinergic pedunculopontine neurons reverses motor deficits in a rat model of Parkinson's disease. Mol Neurodegener 2015; 10:47. [PMID: 26394842 PMCID: PMC4580350 DOI: 10.1186/s13024-015-0044-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 09/08/2015] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Patients with advanced Parkinson's disease (PD) often present with axial symptoms, including postural- and gait difficulties that respond poorly to dopaminergic agents. Although deep brain stimulation (DBS) of a highly heterogeneous brain structure, the pedunculopontine nucleus (PPN), improves such symptoms, the underlying neuronal substrate responsible for the clinical benefits remains largely unknown, thus hampering optimization of DBS interventions. Choline acetyltransferase (ChAT)::Cre(+) transgenic rats were sham-lesioned or rendered parkinsonian through intranigral, unihemispheric stereotaxic administration of the ubiquitin-proteasomal system inhibitor, lactacystin, combined with designer receptors exclusively activated by designer drugs (DREADD), to activate the cholinergic neurons of the nucleus tegmenti pedunculopontine (PPTg), the rat equivalent of the human PPN. We have previously shown that the lactacystin rat model accurately reflects aspects of PD, including a partial loss of PPTg cholinergic neurons, similar to what is seen in the post-mortem brains of advanced PD patients. RESULTS In this manuscript, we show that transient activation of the remaining PPTg cholinergic neurons in the lactacystin rat model of PD, via peripheral administration of the cognate DREADD ligand, clozapine-N-oxide (CNO), dramatically improved motor symptoms, as was assessed by behavioral tests that measured postural instability, gait, sensorimotor integration, forelimb akinesia and general motor activity. In vivo electrophysiological recordings revealed increased spiking activity of PPTg putative cholinergic neurons during CNO-induced activation. c-Fos expression in DREADD overexpressed ChAT-immunopositive (ChAT+) neurons of the PPTg was also increased by CNO administration, consistent with upregulated neuronal activation in this defined neuronal population. CONCLUSIONS Overall, these findings provide evidence that functional modulation of PPN cholinergic neurons alleviates parkinsonian motor symptoms.
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Affiliation(s)
- Ilse S Pienaar
- Centre for Neuroinflammation and Neurodegeneration, Division of Brain Sciences, Faculty of Medicine, Imperial College London, London, W12 ONN, UK.
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK.
| | - Sarah E Gartside
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Puneet Sharma
- Centre for Neuroinflammation and Neurodegeneration, Division of Brain Sciences, Faculty of Medicine, Imperial College London, London, W12 ONN, UK
| | - Vincenzo De Paola
- Medical Research Council Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Sabine Gretenkord
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Dominic Withers
- Medical Research Council Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Joanna L Elson
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK
- Centre for Human Metabonomics, North-West University, Potchefstroom, South Africa
| | - David T Dexter
- Centre for Neuroinflammation and Neurodegeneration, Division of Brain Sciences, Faculty of Medicine, Imperial College London, London, W12 ONN, UK
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Bordas C, Kovacs A, Pal B. The M-current contributes to high threshold membrane potential oscillations in a cell type-specific way in the pedunculopontine nucleus of mice. Front Cell Neurosci 2015; 9:121. [PMID: 25904846 PMCID: PMC4388076 DOI: 10.3389/fncel.2015.00121] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/17/2015] [Indexed: 11/24/2022] Open
Abstract
The pedunculopontine nucleus is known as a cholinergic nucleus of the reticular activating system, participating in regulation of sleep and wakefulness. Besides cholinergic neurons, it consists of GABAergic and glutamatergic neurons as well. According to classical and recent studies, more subgroups of neurons were defined. Groups based on the neurotransmitter released by a neuron are not homogenous, but can be further subdivided. The PPN neurons do not only provide cholinergic and non-cholinergic inputs to several subcortical brain areas but they are also targets of cholinergic and other different neuromodulatory actions. Although cholinergic neuromodulation has been already investigated in the nucleus, one of its characteristic targets, the M-type potassium current has not been described yet. Using slice electrophysiology, we provide evidence in the present work that cholinergic neurons possess M-current, whereas GABAergic neurons lack it. The M-current contributes to certain functional differences of cholinergic and GABAergic neurons, as spike frequency adaptation, action potential firing frequency or the amplitude difference of medium afterhyperpolarizations (AHPs). Furthermore, we showed that high threshold membrane potential oscillation with high power, around 20 Hz frequency is a functional property of almost all cholinergic cells, whereas GABAergic neurons have only low amplitude oscillations. Blockade of the M-current abolished the oscillatory activity at 20 Hz, and largely diminished it at other frequencies. Taken together, the M-current seems to be characteristic for PPN cholinergic neurons. It provides a possibility for modulating gamma band activity of these cells, thus contributing to neuromodulatory regulation of the reticular activating system.
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Affiliation(s)
- Csilla Bordas
- Faculty of Medicine, Department of Physiology, University of Debrecen Debrecen, Hungary
| | - Adrienn Kovacs
- Faculty of Medicine, Department of Physiology, University of Debrecen Debrecen, Hungary
| | - Balazs Pal
- Faculty of Medicine, Department of Physiology, University of Debrecen Debrecen, Hungary
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Tattersall TL, Stratton PG, Coyne TJ, Cook R, Silberstein P, Silburn PA, Windels F, Sah P. Imagined gait modulates neuronal network dynamics in the human pedunculopontine nucleus. Nat Neurosci 2014; 17:449-54. [DOI: 10.1038/nn.3642] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 01/02/2014] [Indexed: 11/09/2022]
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Off the beaten path: drug addiction and the pontine laterodorsal tegmentum. ISRN NEUROSCIENCE 2013; 2013:604847. [PMID: 24959564 PMCID: PMC4045562 DOI: 10.1155/2013/604847] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 05/29/2013] [Indexed: 02/01/2023]
Abstract
Drug addiction is a multileveled behavior controlled by interactions among many diverse neuronal groups involving several neurotransmitter systems. The involvement of brainstem-sourced, cholinergic neurotransmission in the development of addiction and in the persistent physiological processes that drive this maladaptive behavior has not been widely investigated. The major cholinergic input to neurons in the midbrain which are instrumental in assessment of reward and assignment of salience to stimuli, including drugs of abuse, sources from acetylcholine- (ACh-) containing pontine neurons of the laterodorsal tegmentum (LDT). Excitatory LDT input, likely cholinergic, is critical in allowing behaviorally relevant neuronal firing patterns within midbrain reward circuitry. Via this control, the LDT is positioned to be importantly involved in development of compulsive, addictive patterns of behavior. The goal of this review is to present the anatomical, physiological, and behavioral evidence suggesting a role of the LDT in the neurobiology underlying addiction to drugs of abuse. Although focus is directed on the evidence supporting a vital participation of the cholinergic neurons of the LDT, data indicating a contribution of noncholinergic LDT neurons to processes underlying addiction are also reviewed. While sparse, available information of actions of drugs of abuse on LDT cells and the output of these neurons as well as their influence on addiction-related behavior are also presented. Taken together, data from studies presented in this review strongly support the position that the LDT is a major player in the neurobiology of drug addiction. Accordingly, the LDT may serve as a future treatment target for efficacious pharmaceutical combat of drug addiction.
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Zitella LM, Mohsenian K, Pahwa M, Gloeckner C, Johnson MD. Computational modeling of pedunculopontine nucleus deep brain stimulation. J Neural Eng 2013; 10:045005. [PMID: 23723145 DOI: 10.1088/1741-2560/10/4/045005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
OBJECTIVE Deep brain stimulation (DBS) near the pedunculopontine nucleus (PPN) has been posited to improve medication-intractable gait and balance problems in patients with Parkinson's disease. However, clinical studies evaluating this DBS target have not demonstrated consistent therapeutic effects, with several studies reporting the emergence of paresthesia and oculomotor side effects. The spatial and pathway-specific extent to which brainstem regions are modulated during PPN-DBS is not well understood. APPROACH Here, we describe two computational models that estimate the direct effects of DBS in the PPN region for human and translational non-human primate (NHP) studies. The three-dimensional models were constructed from segmented histological images from each species, multi-compartment neuron models and inhomogeneous finite element models of the voltage distribution in the brainstem during DBS. MAIN RESULTS The computational models predicted that: (1) the majority of PPN neurons are activated with -3 V monopolar cathodic stimulation; (2) surgical targeting errors of as little as 1 mm in both species decrement activation selectivity; (3) specifically, monopolar stimulation in caudal, medial, or anterior PPN activates a significant proportion of the superior cerebellar peduncle (up to 60% in the human model and 90% in the NHP model at -3 V); (4) monopolar stimulation in rostral, lateral or anterior PPN activates a large percentage of medial lemniscus fibers (up to 33% in the human model and 40% in the NHP model at -3 V) and (5) the current clinical cylindrical electrode design is suboptimal for isolating the modulatory effects to PPN neurons. SIGNIFICANCE We show that a DBS lead design with radially-segmented electrodes may yield improved functional outcome for PPN-DBS.
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Affiliation(s)
- Laura M Zitella
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, USA
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27
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Abstract
An under-appreciated clue about pathogenesis in Parkinson disease (PD) is the distribution of pathology in the early and middle stages of the disease. This pathological 'roadmap' shows that in addition to dopaminergic neurons in the substantia nigra pars compacta (SNc), a significant number of other central and peripheral neuronal populations exhibit Lewy pathology, phenotypic dysregulation or frank degeneration in PD patients. This spatially distributed, at-risk population of neurons shares a number of features, including autonomously generated activity, broad action potentials, low intrinsic calcium buffering capacity and long, poorly myelinated, highly branched axons. Many, and perhaps all, of these traits add to the metabolic burden in these neurons, suggesting that mitochondrial deficits could drive pathogenesis in PD-in agreement with a large segment of the literature. What is less clear is how this neuronal phenotype might shape the susceptibility to proteostatic dysfunction or to the spread of α-synuclein fibrils deposited in the extracellular space. The review explores the literature on these issues and their translational implications.
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Affiliation(s)
- D James Surmeier
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
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28
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Sakai K. Discharge properties of presumed cholinergic and noncholinergic laterodorsal tegmental neurons related to cortical activation in non-anesthetized mice. Neuroscience 2012; 224:172-90. [PMID: 22917614 DOI: 10.1016/j.neuroscience.2012.08.032] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 08/08/2012] [Accepted: 08/15/2012] [Indexed: 12/29/2022]
Abstract
We have recorded, for the first time, in non-anesthetized, head-restrained mice, a total of 339 single units in and around the laterodorsal (LDT) and sublaterodorsal (SubLDT) tegmental nuclei, which are located, respectively, in, or beneath, the periaqueductal gray and contain cholinergic neurons. The recordings were made during the complete wake-sleep cycle including wakefulness (W), slow-wave sleep (SWS), and paradoxical (or rapid eye movement) sleep (PS). The tegmental neurons displayed either a biphasic narrow or triphasic broad action potential. Seventy-six LDT or SubLDT neurons characterized by their triphasic long-duration action potentials were judged to be cholinergic and this was verified in anesthetized mice using neurobiotin juxtacellular labeling combined with choline acetyltransferase immunohistochemistry of the recorded cell. The 76 presumed cholinergic neurons discharged tonically at the highest rate during W and PS (W/PS-active neurons) as either single isolated spikes or clusters of two to five spikes, and 26 of them discharged selectively during W and PS, these W/PS-selective neurons being found mainly in the SubLDT. The clustering discharge was particularly prominent during PS, when it was associated with an obvious phasic change in the cortical electroencephalogram (EEG), and during waking periods, when it was accompanied by abrupt body movements. During the transition from sleep to waking, the cholinergic W/PS-selective neurons and the LDT or SubLDT noncholinergic W-selective neurons showed firing before the onset of W, while, at the transition from waking to sleep, they ceased firing before sleep onset. At the transition from SWS to PS, all the cholinergic neurons exhibited a significant increase in discharge rate before the onset of PS. The present study in mice supports the view that cholinergic and noncholinergic LDT and SubLDT neurons play an important role in tonic and phasic processes of arousal and cortical EEG activation occurring during W or PS, as well as in the sleep/waking switch.
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Affiliation(s)
- K Sakai
- INSERM U1028, CNRS UMR5292, Neuroscience Research Center, University Lyon 1, Integrative Physiology of the Brain Arousal System, F-69373 Lyon, France.
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Lourens MAJ, Meijer HGE, Heida T, Marani E, van Gils SA. The pedunculopontine nucleus as an additional target for deep brain stimulation. Neural Netw 2011; 24:617-30. [PMID: 21458229 DOI: 10.1016/j.neunet.2011.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 02/08/2011] [Accepted: 03/05/2011] [Indexed: 10/18/2022]
Abstract
The pedunculopontine nucleus has been suggested as a target for DBS. In this paper we propose a single compartment computational model for a PPN Type I cell and compare its dynamic behavior with experimental data. The model shows bursts after a period of hyperpolarization and spontaneous firing at 8 Hz. Bifurcation analysis of the single PPN cell shows bistability of fast and slow spiking solutions for a range of applied currents. A network model for STN, GPe and GPi produces basal ganglia output that is used as input for the PPN cell. The conductances for projections from the STN and the GPi to the PPN are determined from experimental data. The resulting behavior of the PPN cell is studied under normal and Parkinsonian conditions of the basal ganglia network. The effect of high frequency stimulation of the STN is considered as well as the effect of combined high frequency stimulation of the STN and the PPN at various frequencies. The relay properties of the PPN cell demonstrate that the combined high frequency stimulation of STN and low frequency (10 Hz, 25 Hz, 40 Hz) stimulation of PPN hardly improves the effect of exclusive STN stimulation. Moreover, PPN-DBS at low stimulation amplitude has a better effect than at higher stimulation amplitude. The effect of PPN output on the basal ganglia is investigated, in particular the effect of STN-DBS and/or PPN-DBS on the pathological firing pattern of STN and GPe cells. PPN-DBS eliminates the pathological firing pattern of STN and GPe cells, whereas STN-DBS and combined STN-DBS and PPN-DBS eliminate the pathological firing pattern only from STN cells.
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Affiliation(s)
- M A J Lourens
- Department of Applied Mathematics, University of Twente, Enschede 7500 AE, The Netherlands.
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Thomson AM, Armstrong WE. Biocytin-labelling and its impact on late 20th century studies of cortical circuitry. BRAIN RESEARCH REVIEWS 2011; 66:43-53. [PMID: 20399808 PMCID: PMC2949688 DOI: 10.1016/j.brainresrev.2010.04.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 04/08/2010] [Accepted: 04/12/2010] [Indexed: 11/15/2022]
Abstract
In recognition of the impact that a powerful new anatomical tool, such as the Golgi method, can have, this essay highlights the enormous influence that biocytin-filling has had on modern neuroscience. This method has allowed neurones that have been recorded intracellularly, 'whole-cell' or juxta-cellularly, to be identified anatomically, forming a vital link between functional and structural studies. It has been applied throughout the nervous system and has become a fundamental component of our technical armoury. A comprehensive survey of the applications to which the biocytin-filling approach has been put, would fill a large volume. This essay therefore focuses on one area, neocortical microcircuitry and the ways in which combining physiology and anatomy have revealed rules that help us explain its previously indecipherable variability and complexity.
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Affiliation(s)
- Alex M Thomson
- Department of Pharmacology, The School of Pharmacy University of London, 29-39 Brunswick Square, London WC1N 1AX, UK.
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31
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The pedunculopontine nucleus as a target for deep brain stimulation. J Neural Transm (Vienna) 2010; 118:1461-8. [PMID: 21194002 DOI: 10.1007/s00702-010-0547-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 11/29/2010] [Indexed: 10/18/2022]
Abstract
The pedunculopontine nucleus (PPN) is a brain stem locomotive center that is also involved in the processing of sensory and behavioral information. The PPN has been recently proposed as a potential target for the treatment of axial symptoms in Parkinson's disease (PD). To date, results of the first series of PD patients treated with PPN deep brain stimulation (DBS) have shown promising results. In this article, we review some of the basic aspects of the PPN as a target and the outcome of the recently published clinical trials.
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32
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Scarnati E, Florio T, Capozzo A, Confalone G, Mazzone P. The pedunculopontine tegmental nucleus: implications for a role in modulating spinal cord motoneuron excitability. J Neural Transm (Vienna) 2010; 118:1409-21. [PMID: 21161714 DOI: 10.1007/s00702-010-0532-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 11/06/2010] [Indexed: 12/19/2022]
Abstract
There is evidence that deep brain stimulation (DBS) of the pedunculopontine tegmental nucleus (PPTg) improves parkinsonian motor signs. The mechanisms that mediate these effects and the modifications that occur in the PPTg in Parkinson's disease (PD) are not fully known and are the object of current debate. The aim of this paper was to critically review available data with respect to (1) the presence of PPTg neurons linked to reticulospinal projections, (2) the involvement of these neurons in modulating spinal reflexes, and (3) the participation of fibers close to or within the PPTg region in such modulation. The PPTg neurons are distributed in a large pontotegmental region, stimulation of which can evoke activity in hindlimb, shoulder and neck muscles, and potentiate motor responses evoked by stimulation of dorsal roots. This influence seems to be carried out by fast-conducting descending fibers, which likely run in the medial reticulospinal pathway. It is yet unclear which neurotransmitters are involved and on which elements of the gray matter of the spinal cord PPTg fibers synapse. The modulation of spinal cord activity which can be achieved by stimulating the PPTg region seems to be mediated not only by PPTg neurons, but also by tecto-reticular fibers which run in the pontotegmental area, and which likely are activated during PPTg-DBS. The importance of these fibers is discussed taking into account the degeneration of PPTg neurons in PD and the benefits in gait and postural control that PPTg-DBS exerts in PD. The potential usefulness of PPTg-DBS in other neurodegenerative disorders characterized by neuronal loss in the brainstem is also considered.
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Affiliation(s)
- Eugenio Scarnati
- Department of Biomedical Sciences and Technologies (STB), University of L'Aquila, Via Vetoio Coppito 2, 67100, L'Aquila, Italy.
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Silkis IG. Analysis of the effects of neuromodulators on the generation of spontaneous pontine-geniculate-occipital (PGO) waves. NEUROCHEM J+ 2010. [DOI: 10.1134/s1819712410030025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Brambilla D, Barajon I, Bianchi S, Opp MR, Imeri L. Interleukin-1 inhibits putative cholinergic neurons in vitro and REM sleep when microinjected into the rat laterodorsal tegmental nucleus. Sleep 2010; 33:919-29. [PMID: 20614852 DOI: 10.1093/sleep/33.7.919] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
STUDY OBJECTIVES REM sleep is suppressed during infection, an effect mimicked by the administration of cytokines such as interleukin-1 (IL-1). In spite of this observation, brain sites and neurochemical systems mediating IL-1-induced suppression of REM sleep have not been identified. Cholinergic neurons in the brainstem laterodorsal tegmental nucleus (LDT) are part of the neuronal circuitry responsible for REM sleep generation. Since IL-1 inhibits acetylcholine synthesis and release, the aim of this study was to test the two different, but related hypotheses. We hypothesized that IL-1 inhibits LDT cholinergic neurons, and that, as a result of this inhibition, IL-1 suppresses REM sleep. DESIGN, MEASUREMENT, AND RESULTS To test these hypotheses, the electrophysiological activity of putative cholinergic LDT neurons was recorded in a rat brainstem slice preparation. Interleukin-1 significantly inhibited the firing rate of 76% of recorded putative cholinergic LDT neurons and reduced the amplitude of glutamatergic evoked potentials in 60% of recorded neurons. When IL-1 (1 ng) was microinjected into the LDT of freely behaving rats, REM sleep was reduced by about 50% (from 12.7% +/- 1.5% of recording time [after vehicle] to 6.1% +/- 1.4% following IL-1 administration) during post-injection hours 3-4. CONCLUSIONS Results of this study support the hypothesis that IL-1 can suppress REM sleep by acting at the level of the LDT nucleus. Furthermore this effect may result from the inhibition of evoked glutamatergic responses and of spontaneous firing of putative cholinergic LDT neurons.
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Affiliation(s)
- Dario Brambilla
- Department of Human Physiology, University of Milan Medical School, Milan, Italy
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Ye M, Hayar A, Strotman B, Garcia-Rill E. Cholinergic modulation of fast inhibitory and excitatory transmission to pedunculopontine thalamic projecting neurons. J Neurophysiol 2010; 103:2417-32. [PMID: 20181729 PMCID: PMC2867582 DOI: 10.1152/jn.01143.2009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Accepted: 02/21/2010] [Indexed: 11/22/2022] Open
Abstract
The pedunculopontine nucleus (PPN) is part of the cholinergic arm of the reticular activating system, which is mostly active during waking and rapid-eye movement sleep. The PPN projects to the thalamus and receives cholinergic inputs from the laterodorsal tegmental nucleus and contralateral PPN. We employed retrograde labeling and whole cell recordings to determine the modulation of GABAergic, glycinergic, and glutamatergic transmission to PPN thalamic projecting neurons, and their postsynaptic responses to the nonspecific cholinergic agonist carbachol. M2 and M4 muscarinic receptor-modulated inhibitory postsynaptic responses were observed in 73% of PPN output neurons; in 12.9%, M1 and nicotinic receptor-mediated excitation was detected; and muscarinic and nicotinic-modulated fast inhibitory followed by slow excitatory biphasic responses were evident in 6.7% of cells. A significant increase in the frequency of spontaneous excitatory postsynaptic currents (EPSCs) and inhibitory postsynaptic currents during carbachol application was observed in 66.2% and 65.2% of efferent neurons, respectively. This effect was blocked by a M1 antagonist or nonselective muscarinic blocker, indicating that glutamatergic, GABAergic, and/or glycinergic neurons projecting to PPN output neurons are excited through muscarinic receptors. Decreases in the frequency of miniature EPSCs, and amplitude of electrical stimulation-evoked EPSCs, were blocked by a M2 antagonist, suggesting the presence of M2Rs at terminals of presynaptic glutamatergic neurons. Carbachol-induced multiple types of postsynaptic responses, enhancing both inhibitory and excitatory fast transmission to PPN thalamic projecting neurons through muscarinic receptors. These results provide possible implications for the generation of different frequency oscillations in PPN thalamic projecting neurons during distinct sleep-wake states.
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Affiliation(s)
- Meijun Ye
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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Shimamoto SA, Larson PS, Ostrem JL, Glass GA, Turner RS, Starr PA. Physiological identification of the human pedunculopontine nucleus. J Neurol Neurosurg Psychiatry 2010; 81:80-6. [PMID: 19828478 PMCID: PMC3806635 DOI: 10.1136/jnnp.2009.179069] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND The pedunculopontine nucleus (PPN) is a brainstem structure with widespread connections to the basal ganglia. Despite the recent introduction of PPN deep brain stimulation (DBS) for the treatment of gait disorders, little is known about its physiology in humans. METHODS Single unit discharge characteristics of neurons in the PPN region were analysed in four patients and PPN local field potentials (LFP) in one patient, recorded during the course of DBS implantation. Two patients had Parkinson disease, and two had non-sinemet responsive parkinsonism. Cell locations were plotted in the coordinate system of a human brainstem atlas. RESULTS Fifty-six units in the PPN region were studied, of which 32 mapped to within PPN boundaries. The mean (SD) discharge rate of neurons in the PPN was 23.2 (15.6) Hz. Spontaneous neuronal firing rate and burst discharge rate were significantly different between neurons in the region dorsal to PPN and those in the PPN. Responses to passive movement of contralateral and ipsilateral limbs were found. Theta and beta band oscillations were present in the PPN LFP. CONCLUSION PPN discharge characteristics may prove useful in the electrophysiological identification of PPN during DBS implantation surgery.
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Affiliation(s)
- S A Shimamoto
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, California, USA
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37
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Humphries MD, Prescott TJ. The ventral basal ganglia, a selection mechanism at the crossroads of space, strategy, and reward. Prog Neurobiol 2009; 90:385-417. [PMID: 19941931 DOI: 10.1016/j.pneurobio.2009.11.003] [Citation(s) in RCA: 243] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 11/12/2009] [Accepted: 11/16/2009] [Indexed: 11/27/2022]
Abstract
The basal ganglia are often conceptualised as three parallel domains that include all the constituent nuclei. The 'ventral domain' appears to be critical for learning flexible behaviours for exploration and foraging, as it is the recipient of converging inputs from amygdala, hippocampal formation and prefrontal cortex, putatively centres for stimulus evaluation, spatial navigation, and planning/contingency, respectively. However, compared to work on the dorsal domains, the rich potential for quantitative theories and models of the ventral domain remains largely untapped, and the purpose of this review is to provide the stimulus for this work. We systematically review the ventral domain's structures and internal organisation, and propose a functional architecture as the basis for computational models. Using a full schematic of the structure of inputs to the ventral striatum (nucleus accumbens core and shell), we argue for the existence of many identifiable processing channels on the basis of unique combinations of afferent inputs. We then identify the potential information represented in these channels by reconciling a broad range of studies from the hippocampal, amygdala and prefrontal cortex literatures with known properties of the ventral striatum from lesion, pharmacological, and electrophysiological studies. Dopamine's key role in learning is reviewed within the three current major computational frameworks; we also show that the shell-based basal ganglia sub-circuits are well placed to generate the phasic burst and dip responses of dopaminergic neurons. We detail dopamine's modulation of ventral basal ganglia's inputs by its actions on pre-synaptic terminals and post-synaptic membranes in the striatum, arguing that the complexity of these effects hint at computational roles for dopamine beyond current ideas. The ventral basal ganglia are revealed as a constellation of multiple functional systems for the learning and selection of flexible behaviours and of behavioural strategies, sharing the common operations of selection-by-disinhibition and of dopaminergic modulation.
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Affiliation(s)
- Mark D Humphries
- Adaptive Behaviour Research Group, Department of Psychology, University of Sheffield, S10 2TN, UK.
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Takano S, Kim J, Ikari Y, Ogaya M, Nakajima K, Oomura Y, Wayner MJ, Sasaki K. Electrophysiological effects of ghrelin on laterodorsal tegmental neurons in rats: an in vitro study. Peptides 2009; 30:1901-8. [PMID: 19646496 DOI: 10.1016/j.peptides.2009.07.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Accepted: 07/20/2009] [Indexed: 10/20/2022]
Abstract
Ghrelin, a gut and brain peptide, is a potent stimulant for growth hormone (GH) secretion and feeding. Recent studies further show a critical role of ghrelin in the regulation of sleep-wakefulness. Laterodorsal tegmental nucleus (LDT), that regulates waking and rapid eye movement (REM) sleep, expresses GH secretagogue receptors (GHS-Rs). Thus, the present study was carried out to examine electrophysiological effects of ghrelin on LDT neurons using rat brainstem slices, and to determine the ionic mechanism involved. Whole cell recording revealed that ghrelin depolarizes LDT neurons dose-dependently in normal artificial cerebrospinal fluid (ACSF). The depolarization persisted in tetrodotoxin-containing ACSF (TTX ACSF), and is partially blocked by the application of [D-Lys3]-GHRP-6, a selective antagonist for GHS-Rs. Membrane resistance during the ghrelin-induced depolarization increased by about 18% than that before the depolarization. In addition, the ghrelin-induced depolarization was drastically reduced in high-K+ TTX ACSF with a K+ concentration of 13.25 mM. Reversal potentials obtained from I-V curves before and during the depolarization were about -83 mV, close to the equilibrium potential of the K+ channel. Most of the LDT neurons recorded were characterized by an A-current or both the A-current and a low threshold Ca2+ spike, and they were predominantly cholinergic. These results indicate that ghrelin depolarizes LDT neurons postsynaptically and dose-dependently via GHS-Rs, and that the ionic mechanisms underlying the ghrelin-induced depolarization include a decrease of K+ conductance. The results also suggest that LDT neurons are implicated in the cellular processes through which ghrelin participates in the regulation of sleep-wakefulness.
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Affiliation(s)
- Shinobu Takano
- Division of Bio-Information Engineering, Faculty of Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
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Kim J, Nakajima K, Oomura Y, Wayner MJ, Sasaki K. Orexin-A and ghrelin depolarize the same pedunculopontine tegmental neurons in rats: an in vitro study. Peptides 2009; 30:1328-35. [PMID: 19540431 DOI: 10.1016/j.peptides.2009.03.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 03/23/2009] [Accepted: 03/23/2009] [Indexed: 11/26/2022]
Abstract
Orexin (ORX), also called hypocretin, and ghrelin are newly identified peptides in the brain and/or peripheral organs, and they are involved in the regulation of sleep-wakefulness as well as feeding. In our previous studies we have found that ORX and ghrelin each depolarizes more than half of the cholinergic neurons recorded in the pedunculopontine tegmental nucleus (PPT) via a dual ionic mechanism including a decrease of K(+) conductance and an increase of nonselective cationic conductance. Thus, the present study was carried out to investigate whether ORX-A and ghrelin both depolarize the same PPT neuron. About 60% of PPT neurons examined was depolarized by both ORX-A and ghrelin, 20% by ORX-A alone, and 10% by ghrelin alone. The remaining 10% did not respond to these peptides. In neurons which were responsive to both ORX-A and ghrelin, the depolarizations induced by ORX-A and ghrelin were additive. In addition, the ORX-A- and ghrelin-induced depolarizations were both blocked by D609, a phosphatidylcholine-specific phospholipase C (PLC) inhibitor. These results suggest that same PPT neurons with receptors for ORX and ghrelin are involved in the cellular process through which ORX and ghrelin participate in the regulation of sleep wakefulness, and that the excitatory effects of ORX and ghrelin on PPT neurons are mediated by PLC.
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Affiliation(s)
- Juhyon Kim
- Division of Bio-Information Engineering, Faculty of Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
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40
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Wang HL, Morales M. Pedunculopontine and laterodorsal tegmental nuclei contain distinct populations of cholinergic, glutamatergic and GABAergic neurons in the rat. Eur J Neurosci 2009; 29:340-58. [PMID: 19200238 DOI: 10.1111/j.1460-9568.2008.06576.x] [Citation(s) in RCA: 360] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The pedunculopontine tegmental nucleus (PPTg) and laterodorsal tegmental nucleus (LDTg) provide cholinergic afferents to several brain areas. This cholinergic complex has been suggested to play a role in sleep, waking, motor function, learning and reward. To have a better understanding of the neurochemical organization of the PPTg/LDTg we characterized the phenotype of PPTg/LDTg neurons by determining in these cells the expression of transcripts encoding choline acetyltransferase (ChAT), glutamic acid decarboxylase (GAD) or the vesicular glutamate transporters (vGluT1, vGluT2 and vGluT3). Within the PPTg/LDTg complex we found neurons expressing ChAT, vGluT2 or GAD transcripts, these neuronal phenotypes were intermingled, but not homogeneously distributed within the PPTg or LDTg. Previous studies suggested the presence of either glutamate or gamma-aminobutyric acid (GABA) immunolabeling in a large number of PPTg/LDTg cholinergic neurons, leading to the widespread notion that PPTg/LDTg cholinergic neurons co-release acetylcholine together with either glutamate or GABA. To assess the glutamatergic or GABAergic nature of the PPTg/LDTg cholinergic neurons, we combined in situ hybridization (to detect vGluT2 or GAD transcripts) and immunohistochemistry (to detect ChAT), and found that over 95% of all PPTg/LDTg cholinergic neurons lack transcripts encoding either vGluT2 mRNA or GAD mRNA. As the vast majority of PPTg/LDTg cholinergic neurons lack transcripts encoding essential proteins for the vesicular transport of glutamate or for the synthesis of GABA, co-release of acetylcholine with either glutamate or GABA is unlikely to be a major factor in the interactions between acetylcholine, glutamate and GABA at the postsynaptic site.
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Affiliation(s)
- Hui-Ling Wang
- Intramural Research Program, Cellular Neurophysiology, Biomedical Research Center, National Institute on Drug Abuse, 251 Bayview Blvd, Baltimore, MD 21224, USA
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Kim J, Nakajima K, Oomura Y, Wayner MJ, Sasaki K. Electrophysiological effects of ghrelin on pedunculopontine tegmental neurons in rats: An in vitro study. Peptides 2009; 30:745-57. [PMID: 19118591 DOI: 10.1016/j.peptides.2008.12.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 12/03/2008] [Accepted: 12/03/2008] [Indexed: 01/08/2023]
Abstract
Ghrelin is a potent stimulant for growth hormone (GH) secretion and feeding. Recent studies further show a critical role of ghrelin in the regulation of sleep-wakefulness. Pedunculopontine tegmental nucleus (PPT), which regulates waking and rapid eye movement (REM) sleep, expresses GH secretagogue receptors (GHS-Rs). Thus, the present study was carried out to examine electrophysiological effects of ghrelin on PPT neurons using rat brainstem slices, and to determine the ionic mechanism involved. Whole cell recording revealed that ghrelin depolarizes PPT neurons dose-dependently in normal artificial cerebrospinal fluid (ACSF). The depolarization persisted in tetrodotoxin-containing ACSF, although action potentials did not occur. Application of [d-Lys(3)]-GHRP-6, a selective antagonist for GHS-Rs, almost blocked the ghrelin-induced depolarization. Furthermore, the ghrelin-induced depolarization was reduced in high K(+) ACSF or low Na(+) ACSF, and abolished in high K(+)-low Na(+) ACSF or in a combination of low Na(+) ACSF and recordings with Cs(+)-containing pipettes. An inhibitor of Na(+)/Ca(2+) exchanger had no effect on the depolarization. Most of the PPT neurons recorded were characterized by an A-current or both the A-current and a low threshold Ca(2+) spike, and they were predominantly cholinergic as revealed by nicotinamide adenine dinucleotide phosphate-diaphorase staining. These results suggest that ghrelin depolarizes PPT neurons postsynaptically and dose-dependently via GHS-Rs, and that the ionic mechanisms underlying the ghrelin-induced depolarization include a decrease of K(+) conductance and an increase of non-selective cationic conductance. The results also support the notion that ghrelin plays a role in the regulation of sleep-wakefulness.
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42
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Kim J, Nakajima K, Oomura Y, Wayner MJ, Sasaki K. Electrophysiological effects of orexins/hypocretins on pedunculopontine tegmental neurons in rats: an in vitro study. Peptides 2009; 30:191-209. [PMID: 18977258 DOI: 10.1016/j.peptides.2008.09.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 09/25/2008] [Accepted: 09/25/2008] [Indexed: 11/29/2022]
Abstract
Orexin-A (ORX-A) and orexin-B (ORX-B) play critical roles in the regulation of sleep-wakefulness and feeding. ORX neurons project to the pedunculopontine tegmental nucleus (PPT), which regulates waking and rapid eye movement (REM) sleep. Thus, we examined electrophysiological effects of ORXs on rat PPT neurons with a soma size of more than 30 microm. Whole cell patch clamp recording in vitro revealed that ORX-A and ORX-B depolarized PPT neurons dose-dependently in normal and/or tetrodotoxin containing artificial cerebrospinal fluids (ACSFs), and the EC(50) values for ORX-A and ORX-B were 66 nM and 536 nM, respectively. SB-334867, a selective inhibitor for ORX 1 (OX(1)) receptors, significantly suppressed the ORX-A-induced depolarization. The ORX-A-induced depolarization was reduced in high K(+) ACSF with extracellular K(+) concentration of 13.25 mM or N-methyl-d-glucamine (NMDG(+))-containing ACSF in which NaCl was replaced with NMDG-Cl, and abolished in high K(+)-NMDG(+) ACSF or in a combination of NMDG(+) ACSF and recordings with Cs(+)-containing pipettes. An inhibitor of Na(+)/Ca(2+) exchanger and chelating intracellular Ca(2+) had no effect on the depolarization. Most of PPT neurons studied were characterized by an A-current or both A-current and a low threshold Ca(2+) spike, and predominantly cholinergic. These results suggest that ORXs directly depolarize PPT neurons via OX(1) receptors and via a dual ionic mechanism including a decrease of K(+) conductances and an increase of non-selective cationic conductances, and support the notion that ORX neurons affect the activity of PPT neurons directly and/or indirectly to control sleep-wakefulness, especially REM sleep.
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Affiliation(s)
- Juhyon Kim
- Division of Bio-Information Engineering, Faculty of Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
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Jenkinson N, Nandi D, Muthusamy K, Ray NJ, Gregory R, Stein JF, Aziz TZ. Anatomy, physiology, and pathophysiology of the pedunculopontine nucleus. Mov Disord 2008; 24:319-28. [DOI: 10.1002/mds.22189] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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Zhang QJ, Liu J, Wang Y, Wang S, Wu ZH, Yan W, Hui YP, Ali U. The firing activity of presumed cholinergic and non-cholinergic neurons of the pedunculopontine nucleus in 6-hydroxydopamine-lesioned rats: an in vivo electrophysiological study. Brain Res 2008; 1243:152-60. [PMID: 18824158 DOI: 10.1016/j.brainres.2008.09.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 09/06/2008] [Accepted: 09/10/2008] [Indexed: 11/19/2022]
Abstract
Several studies have shown that the neuronal activity of the pedunculopontine nucleus is increased in Parkinson's disease. In the present study, the changes were examined in the firing rate and firing pattern of presumed cholinergic and non-cholinergic neurons in the pedunculopontine nucleus of 6-hydroxydopamine-lesioned rats by using extracellular recording. In the lesioned rats, the mean firing rate of both presumed cholinergic and non-cholinergic neurons in the pedunculopontine nucleus increased significantly compared to normal rats. With regard to firing pattern, the majority of presumed cholinergic and non-cholinergic neurons fired regularly in normal rats. After substantia nigra pars compacta-lesion, the percentage of presumed non-cholinergic neurons exhibiting irregular pattern increased significantly compared to normal rats, while having no significant change in the firing pattern of presumed cholinergic neurons. Collectively, these results indicate that the presumed cholinergic and non-cholinergic neurons in the pedunculopontine nucleus are overactive in 6-hydroxydopamine-lesioned rats, particularly, presumed non-cholinergic neuron firing is more irregular, which suggests that the firing activity of presumed cholinergic and non-cholinergic neurons is affected by the different afferents from the basal ganglia and related structures.
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Affiliation(s)
- Qiao Jun Zhang
- Department of Neurology, Second Affiliated Hospital, Medical School of Xi'an Jiaotong University, Xi'an 710004, China
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Turner MS, Gray TS, Mickiewicz AL, Napier TC. Fos expression following activation of the ventral pallidum in normal rats and in a model of Parkinson's Disease: implications for limbic system and basal ganglia interactions. Brain Struct Funct 2008; 213:197-213. [PMID: 18663473 DOI: 10.1007/s00429-008-0190-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 07/02/2008] [Indexed: 10/21/2022]
Abstract
The circuit-related consequences of activating the ventral pallidum (VP) are not well known, and lacking in particular is how these effects are altered in various neuropathological states. To help to address these paucities, this study investigated the brain regions affected by VP activation by quantifying neurons that stain for Fos-like immunoreactivity (ir). Fos-ir was assessed after intra-pallidal injections of the excitatory amino acid agonist, NMDA, or the GABA(A) antagonist, bicuculline in normal rats and in those rendered Parkinsonian-like by lesioning dopaminergic neurons with the neurotoxin, 6-OHDA. We hypothesized that activation of the VP will alter the activity state of brain regions associated with both the basal ganglia and limbic system, and that this influence would be modified in the Parkinsonian state. Blocking tonically activated GABA(A) receptors with bicuculline (50 ng/0.5 microl) elevated Fos-ir in the VP to 423% above the contralateral, vehicle-injected side. Likewise, intra-VP NMDA (0.23 microg or 0.45 microg/0.5 microl), dose-dependently increased the number of pallidal neurons expressing Fos-ir by 224 and 526%, respectively. At higher NMDA doses, the density of Fos-ir neurons was not elevated above control levels. This inverted U-shaped profile was mirrored by a VP output structure, the medial subthalamic nucleus (mSTN). The mSTN showed a 289% increase in Fos-ir neurons with intra-VP injections of 0.45 microg NMDA, and this response was halved following intra-VP injections of 0.9 microg NMDA. Of the 12 other brain regions measured, three showed VP NMDA-induced enhancements in Fos-ir: the frontal cortex, entopeduncular nucleus and substantia nigra pars reticulata, all regions associated with the basal ganglia. In a second study, we evaluated the NMDA activation profile in a rat model of Parkinson's Disease (PD) which was created by a unilateral injection of 6-OHDA into the rostral substantia nigra pars compacta. Comparisons of responses to intra-VP NMDA between the hemispheres ipsilateral and contralateral to the lesion revealed that Fos-ir cells in the pedunculopontine nucleus was reduced by 62%, whereas Fos-ir for the basolateral amygdala and STN was reduced by 32 and 42%, respectively. These findings support the concept that the VP can influence both the basal ganglia and the limbic system, and that that the nature of this influence is modified in an animal model of PD. As the VP regulates motivation and cognition, adaptations in this system may contribute to the mood and mnemonic disorders that can accompany PD.
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Affiliation(s)
- Michael S Turner
- M.D./Ph.D. Program and the Neuroscience Graduate Program, Loyola University Chicago, Medical Center, Maywood, IL, USA
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Aravamuthan BR, Bergstrom DA, French RA, Taylor JJ, Parr-Brownlie LC, Walters JR. Altered neuronal activity relationships between the pedunculopontine nucleus and motor cortex in a rodent model of Parkinson's disease. Exp Neurol 2008; 213:268-80. [PMID: 18601924 DOI: 10.1016/j.expneurol.2008.05.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Revised: 05/08/2008] [Accepted: 05/29/2008] [Indexed: 01/10/2023]
Abstract
The pedunculopontine nucleus (PPN) is a new deep brain stimulation (DBS) target for Parkinson's disease (PD), but little is known about PPN firing pattern alterations in PD. The anesthetized rat is a useful model for investigating the effects of dopamine loss on the transmission of oscillatory cortical activity through basal ganglia structures. After dopamine loss, synchronous oscillatory activity emerges in the subthalamic nucleus and substantia nigra pars reticulata in phase with cortical slow oscillations. To investigate the impact of dopamine cell lesion-induced changes in basal ganglia output on activity in the PPN, this study examines PPN spike timing with reference to motor cortex (MCx) local field potential (LFP) activity in urethane- or ketamine-anesthetized rats. Seven to ten days after unilateral 6-hydroxydopamine lesion of the medial forebrain bundle, spectral power in PPN spike trains and coherence between PPN spiking and PPN LFP activity increased in the approximately 1 Hz range in urethane-anesthetized rats. PPN spike timing also changed from firing predominantly in phase with MCx slow oscillations in the intact urethane-anesthetized rat to firing predominantly antiphase to MCx oscillations in the hemi-parkinsonian rat. These changes were not observed in the ketamine-anesthetized preparation. These observations suggest that dopamine loss alters PPN spike timing by increasing inhibitory oscillatory input to the PPN from basal ganglia output nuclei, a phenomenon that may be relevant to motor dysfunction and PPN DBS efficacy in PD patients.
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Affiliation(s)
- Bhooma R Aravamuthan
- Neurophysiological Pharmacology Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892-3702, USA
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Florio T, Scarnati E, Confalone G, Minchella D, Galati S, Stanzione P, Stefani A, Mazzone P. High-frequency stimulation of the subthalamic nucleus modulates the activity of pedunculopontine neurons through direct activation of excitatory fibres as well as through indirect activation of inhibitory pallidal fibres in the rat. Eur J Neurosci 2007; 25:1174-86. [PMID: 17331213 DOI: 10.1111/j.1460-9568.2007.05360.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Recent data suggest a potential role of pedunculopontine nucleus (PPN) electrical stimulation in improving gait and posture in Parkinson's disease. Because the PPN receives fibres from the subthalamic nucleus (STN), we investigated the effects of STN-high-frequency stimulation (HFS) on PPN neuronal activity in intact rats and in rats bearing either an ibotenate lesion of the entopeduncular nucleus (EP) or a lesion of the substantia nigra (SN). The main response of PPN neurons to STN single-shock stimulations in the three experimental groups was a short latency (4.5 +/- 2.1 ms) and brief (15.3 +/- 6.5 ms) excitation. This response was maintained during 1-5 s of STN-HFS (130 Hz, 60 micros, 100-1000 microA). In EP-lesioned rats the percentage (75.0%) of PPN neurons showing a modulation of activity following STN-HFS was significantly higher compared with that observed in intact (39.7%) and in SN-lesioned rats (35.4%). Furthermore, in EP-lesioned rats the most frequent response of PPN neurons following STN-HFS was a 5-20 s excitation, which was present in 76.6% of responsive neurons in comparison to 15.4% and 9.1% of neurons responsive in intact and in 6-hydroxydopamine-lesioned rats, respectively. Neurons responsive to STN-HFS in the three experimental groups showed either a sharp positively skewed distribution of interspike intervals or multisecond oscillations in autocorrelograms. The results support that STN-HFS modulates the PPN through a balance of excitatory and inhibitory influences, which may be independent from the dopaminergic nigral neurons. In the absence of inhibitory EP fibres, the direct excitatory influence exerted by the STN on the PPN appears to predominate.
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Affiliation(s)
- Tiziana Florio
- Department of Sciences and Biomedical Technologies, University of L'Aquila, L'Aquila, Italy
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48
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Abstract
Using GABAergic outputs from the SNr or GP(i), the basal ganglia exert inhibitory control over several motor areas in the brainstem which in turn control the central pattern generators for the basic motor repertoire including eye-head orientation, locomotion, mouth movements, and vocalization. These movements are by default kept suppressed by tonic rapid firing of SNr/GP(i) neurons, but can be released by a selective removal of the tonic inhibition. Derangement of the SNr/GP(i) outputs leads to either an inability to initiate movements (akinesia) or an inability to suppress movements (involuntary movements). Although the spatio-temporal patterns of individual movements are largely innate and fixed, it is essential for survival to select appropriate movements and arrange them in an appropriate order depending on the context, and this is what the basal ganglia presumably do. To achieve such a goal, however, the basal ganglia need to be trained to optimize their outputs with the aid of cortical inputs carrying sensorimotor and cognitive information and dopaminergic inputs carrying reward-related information. The basal ganglia output to the thalamus, which is particularly developed in primates, provides the basal ganglia with an advanced ability to organize behavior by including the motor skill mechanisms in which new movement patterns can be created by practice. To summarize, an essential function of the basal ganglia is to select, sort, and integrate innate movements and learned movements, together with cognitive and emotional mental operations, to achieve purposeful behaviors. Intricate hand-finger movements do not occur in isolation; they are always associated with appropriate motor sets, such as eye-head orientation and posture.
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Affiliation(s)
- O Hikosaka
- Laboratory of Sensorimotor Research, National Eye Institute, National Institute of Health, 49 Convent Drive, Bldg. 49, Rm. 2A50, Bethesda, MD 20892-4435, USA.
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Good CH, Bay KD, Buchanan R, Skinner RD, Garcia-Rill E. Muscarinic and nicotinic responses in the developing pedunculopontine nucleus (PPN). Brain Res 2006; 1129:147-55. [PMID: 17156760 DOI: 10.1016/j.brainres.2006.10.046] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2006] [Revised: 10/19/2006] [Accepted: 10/21/2006] [Indexed: 12/29/2022]
Abstract
The pedunculopontine nucleus (PPN), the cholinergic arm of the reticular activating system (RAS), is known to modulate waking and rapid eye movement (REM) sleep. REM sleep decreases between 10 and 30 days postnatally in the rat, with the majority occurring between 12 and 21 days. We investigated the possibility that changes in the cholinergic, muscarinic and/or nicotinic, input to PPN neurons could explain at least part of the developmental decrease in REM sleep. We recorded intracellularly from PPN neurons in 12-21 day rat brainstem slices maintained in artificial cerebrospinal fluid (aCSF) and found that application of the nicotinic agonist 1,1-dimethyl-4-phenyl-piperazinium iodide (DMPP) depolarized PPN neurons early in development, then hyperpolarized PPN neurons by day 21. Most of the effects of DMPP persisted following application of the sodium channel blocker tetrodotoxin (TTX), and in the presence of glutamatergic, serotonergic, noradrenergic and GABAergic antagonists, but were blocked by the nicotinic antagonist mecamylamine (MEC). The mixed muscarinic agonist carbachol (CAR) hyperpolarized all type II (A current) PPN cells and depolarized all type I (low threshold spike-LTS current) and type III (A+LTS current) PPN cells, but did not change effects during the period known for the developmental decrease in REM sleep. The effects of CAR persisted in the presence of TTX but were mostly blocked by the muscarinic antagonist atropine (ATR), and the remainder by MEC. We conclude that, while the nicotinic inputs to the PPN may help modulate the developmental decrease in REM sleep, the muscarinic inputs appear to modulate different types of cells differentially.
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Affiliation(s)
- Cameron H Good
- Center for Translational Neuroscience, Department of Neurobiology and Developmental Sciences, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205-7199, USA
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Winn P. How best to consider the structure and function of the pedunculopontine tegmental nucleus: Evidence from animal studies. J Neurol Sci 2006; 248:234-50. [PMID: 16765383 DOI: 10.1016/j.jns.2006.05.036] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This review presents the hypothesis that the best way to consider the pedunculopontine tegmental nucleus is by analogy with the substantia nigra. The substantia nigra contains two main compartments: the pars compacta and the pars reticulata. The former contains dopamine neurons that project widely within the basal ganglia while the latter is in receipt of corticostriatal output. Similarly, the PPTg contains the Ch5 acetylcholine containing neurons that project to the thalamus and corticostriatal systems (notably the pars compacta of substantia nigra and the subthalamic nucleus) while the non-cholinergic neurons of the pedunculopontine are in receipt of corticostriatal output. Assessment of the location, composition and connections of the pedunculopontine tegmental nucleus is made to support the hypothesis that it has structural similarities with substantia nigra. Assessment of the motor, sensory and cognitive functions of the pedunculopontine is also made, suggesting functional similarities exist also. Having a clear model of pedunculopontine structure and function is a matter of some importance. It is clearly involved in Parkinson's disease and could potentially be a target for therapeutic intervention. If this is to be realized it will be best to have as clear an understanding as possible of pedunculopontine structure and function in order to maximize positive benefits.
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Affiliation(s)
- Philip Winn
- School of Psychology, University of St Andrews, St Mary's Quad, South Street, St Andrews, Fife KY16 9JP, United Kingdom.
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