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Santin MDN, Tempier N, Belaid H, Zenoni M, Dumas S, Wallén-Mackenzie Å, Bardinet E, Destrieux C, François C, Karachi C. Anatomical characterisation of three different psychosurgical targets in the subthalamic area: from the basal ganglia to the limbic system. Brain Struct Funct 2023; 228:1977-1992. [PMID: 37668733 DOI: 10.1007/s00429-023-02691-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 07/24/2023] [Indexed: 09/06/2023]
Abstract
Effective neural stimulation for the treatment of severe psychiatric disorders needs accurate characterisation of surgical targets. This is especially true for the medial subthalamic region (MSR) which contains three targets: the anteromedial STN for obsessive compulsive disorder (OCD), the medial forebrain bundle (MFB) for depression and OCD, and the "Sano triangle" for pathological aggressiveness. Blocks containing the subthalamic area were obtained from two human brains. After obtaining 11.7-Tesla MRI, blocks were cut in regular sections for immunohistochemistry. Fluorescent in situ hybridisation was performed on the macaque MSR. Electron microscopic observation for synaptic specialisation was performed on human and macaque subthalamic fresh samples. Images of human brain sections were reconstructed in a cryoblock which was registered on the MRI and histological slices were then registered. The STN contains glutamatergic and fewer GABAergic neurons and has no strict boundary with the adjacent MSR. The anteromedial STN has abundant dopaminergic and serotoninergic innervation with very sparse dopaminergic neurons. The MFB is composed of dense anterior dopaminergic and posterior serotoninergic fibres, and fewer cholinergic and glutamatergic fibres. Medially, the Sano triangle presumably contains orexinergic terminals from the hypothalamus, and neurons with strong nuclear oestrogen receptor-alpha staining with a decreased anteroposterior and mediolateral gradient of staining. These findings provide new insight regarding MSR cells and their fibre specialisation, forming a transition zone between the basal ganglia and the limbic systems. Our 3D reconstruction enabled us to visualize the main histological features of the three targets which should enable better targeting and understanding of neuromodulatory stimulation results in severe psychiatric conditions.
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Affiliation(s)
- Marie des Neiges Santin
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute- ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, 75013, Paris, France
| | - Nicolas Tempier
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute- ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, 75013, Paris, France
| | - Hayat Belaid
- Service de Neurochirurgie, Hôpital Fondation Adolphe de Rothschild, 29 rue Manin, Paris, France
| | - Matthieu Zenoni
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute- ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, 75013, Paris, France
| | | | - Åsa Wallén-Mackenzie
- Department of Organismal Biology, Unit of Comparative Physiology, Uppsala University, S-756 32, Uppsala, Sweden
| | - Eric Bardinet
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute- ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, 75013, Paris, France
| | - Christophe Destrieux
- UMR Inserm U1253, IBrain, Université de Tours, Tours, France
- Laboratoire d'Anatomie, Faculté de Médecine, Université François Rabelais, Tours, France
| | - Chantal François
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute- ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, 75013, Paris, France
| | - Carine Karachi
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute- ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, 75013, Paris, France.
- AP-HP, Hôpital de la Pitié-Salpêtrière, Service de Neurochirurgie, Paris, France.
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Cover KK, Mathur BN. Axo-axonic synapses: Diversity in neural circuit function. J Comp Neurol 2021; 529:2391-2401. [PMID: 33314077 PMCID: PMC8053672 DOI: 10.1002/cne.25087] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 12/20/2022]
Abstract
The chemical synapse is the principal form of contact between neurons of the central nervous system. These synapses are typically configured as presynaptic axon terminations onto postsynaptic dendrites or somata, giving rise to axo-dendritic and axo-somatic synapses, respectively. Beyond these common synapse configurations are less-studied, non-canonical synapse types that are prevalent throughout the brain and significantly contribute to neural circuit function. Among these are the axo-axonic synapses, which consist of an axon terminating on another axon or axon terminal. Here, we review evidence for axo-axonic synapse contributions to neural signaling in the mammalian nervous system and survey functional neural circuit motifs enabled by these synapses. We also detail how recent advances in microscopy, transgenics, and biological sensors may be used to identify and functionally assay axo-axonic synapses.
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Affiliation(s)
- Kara K. Cover
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD USA 21201
| | - Brian N. Mathur
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD USA 21201
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Dong J, Hawes S, Wu J, Le W, Cai H. Connectivity and Functionality of the Globus Pallidus Externa Under Normal Conditions and Parkinson's Disease. Front Neural Circuits 2021; 15:645287. [PMID: 33737869 PMCID: PMC7960779 DOI: 10.3389/fncir.2021.645287] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 02/05/2021] [Indexed: 12/18/2022] Open
Abstract
The globus pallidus externa (GPe) functions as a central hub in the basal ganglia for processing motor and non-motor information through the creation of complex connections with the other basal ganglia nuclei and brain regions. Recently, with the adoption of sophisticated genetic tools, substantial advances have been made in understanding the distinct molecular, anatomical, electrophysiological, and functional properties of GPe neurons and non-neuronal cells. Impairments in dopamine transmission in the basal ganglia contribute to Parkinson's disease (PD), the most common movement disorder that severely affects the patients' life quality. Altered GPe neuron activity and synaptic connections have also been found in both PD patients and pre-clinical models. In this review, we will summarize the main findings on the composition, connectivity and functionality of different GPe cell populations and the potential GPe-related mechanisms of PD symptoms to better understand the cell type and circuit-specific roles of GPe in both normal and PD conditions.
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Affiliation(s)
- Jie Dong
- Laboratory of Neurogenetics, Transgenic Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States
| | - Sarah Hawes
- Laboratory of Neurogenetics, Transgenic Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States
| | - Junbing Wu
- Child Health Institute of New Jersey, Rutgers University, New Brunswick, NJ, United States
| | - Weidong Le
- Liaoning Provincial Center for Clinical Research on Neurological Diseases & Liaoning Provincial Key Laboratory for Research on the Pathogenic Mechanisms of Neurological Diseases, The First Affiliated Hospital of Dalian Medical University, Dalian, China.,Medical School of University of Electronic Science and Technology of China, Institute of Neurology, Sichuan Provincial Hospital, Sichuan Academy of Medical Science, Chengdu, China
| | - Huaibin Cai
- Laboratory of Neurogenetics, Transgenic Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States
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Gagnon D, Eid L, Coudé D, Whissel C, Di Paolo T, Parent A, Parent M. Evidence for Sprouting of Dopamine and Serotonin Axons in the Pallidum of Parkinsonian Monkeys. Front Neuroanat 2018; 12:38. [PMID: 29867377 PMCID: PMC5963193 DOI: 10.3389/fnana.2018.00038] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 04/25/2018] [Indexed: 12/25/2022] Open
Abstract
This light and electron microscopie immunohistochemical quantitative study aimed at determining the state of the dopamine (DA) and serotonin (5-HT) innervations of the internal (GPi) and external (GPe) segments of the pallidum in cynomolgus monkeys (Macaca fascicularis) rendered parkinsonian by systemic injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In contrast to the prominent DA denervation of striatum, the GPi in MPTP monkeys was found to be markedly enriched in DA (TH+) axon varicosities. The posterior sensorimotor region of this major output structure of the basal ganglia was about 8 times more intensely innervated in MPTP monkeys (0.71 ± 0.08 × 106 TH+ axon varicosities/mm3) than in controls (0.09 ± 0.01 × 106). MPTP intoxication also induced a two-fold increase in the density of 5-HT (SERT+) axon varicosities in both GPe and GPi. This augmentation was particularly pronounced anteriorly in the so-called associative and limbic pallidal territories. The total length of the labeled pallidal axons was also significantly increased in MPTP monkeys compared to controls, but the number of DA and 5-HT axon varicosities per axon length unit remained the same in the two groups, indicating that the DA and 5-HT pallidal hyperinnervations seen in MPTP monkeys result from axon sprouting rather than from the appearance of newly formed axon varicosities on non-growing axons. At the ultrastructural level, pallidal TH+ and SERT+ axons were morphologically similar in MPTP and controls, and their synaptic incidence was very low suggesting a volumic mode of transmission. Altogether, our data reveal a significant sprouting of DA and 5-HT pallidal afferents in parkinsonian monkeys, the functional significance of which remains to be determined. We suggest that the marked DA hyperinnervation of the GPi represents a neuroadaptive change designed to normalize pallidal firing patterns associated with the delayed appearance of motor symptoms, whereas the 5-HT hyperinnervation might be involved in the early expression of non-motor symptoms in Parkinson's disease.
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Affiliation(s)
- Dave Gagnon
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
| | - Lara Eid
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
| | - Dymka Coudé
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
| | - Carl Whissel
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
| | - Thérèse Di Paolo
- Faculty of Pharmacy, Centre de Recherche du CHU de Québec, Université Laval, Quebec City, QC, Canada
| | - André Parent
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
| | - Martin Parent
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Université Laval, Quebec City, QC, Canada
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Eid L, Parent M. Preparation of Non-human Primate Brain Tissue for Pre-embedding Immunohistochemistry and Electron Microscopy. J Vis Exp 2017. [PMID: 28448038 DOI: 10.3791/55397] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Despite all the technological advances at the light microscopy level, electron microscopy remains the only tool in neuroscience to examine and characterize ultrastructural and morphological details of neurons, such as synaptic contacts. Good preservation of brain tissue for electron microscopy can be obtained by rigorous cryo-fixation methods, but these techniques are rather costly and limit the use of immunolabeling, which is crucial to understand the connectivity of identified neuronal systems. Freeze-substitution methods have been developed to allow the combination of cryo-fixation with immunolabeling. However, the reproducibility of these methodological approaches usually relies on costly freezing devices. Moreover, achieving reliable results with this technique is very time-consuming and skill-challenging. Hence, the traditional chemically fixed brain, particularly with acrolein fixative, remains a time-efficient and low-cost method to combine electron microscopy with immunohistochemistry. Here, we provide a reliable experimental protocol using chemical acrolein fixation that leads to the preservation of primate brain tissue and is compatible with pre-embedding immunohistochemistry and transmission electron microscopic examination.
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Affiliation(s)
- Lara Eid
- Centre de recherche de l'Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Université Laval; Centre de recherche du CHU Sainte-Justine;
| | - Martin Parent
- Centre de recherche de l'Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Université Laval
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