1
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Mazengenya P, Lesku JA, Rattenborg NC, Manger PR. Apparent absence of hypothalamic cholinergic neurons in the common ostrich and emu: Implications for global brain states during sleep. J Comp Neurol 2024; 532:e25587. [PMID: 38335048 DOI: 10.1002/cne.25587] [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: 09/11/2023] [Revised: 11/28/2023] [Accepted: 01/09/2024] [Indexed: 02/12/2024]
Abstract
We examined the presence/absence and parcellation of cholinergic neurons in the hypothalami of five birds: a Congo grey parrot (Psittacus erithacus), a Timneh grey parrot (P. timneh), a pied crow (Corvus albus), a common ostrich (Struthio camelus), and an emu (Dromaius novaehollandiae). Using immunohistochemistry to an antibody raised against the enzyme choline acetyltransferase, hypothalamic cholinergic neurons were observed in six distinct clusters in the medial, lateral, and ventral hypothalamus in the parrots and crow, similar to prior observations made in the pigeon. The expression of cholinergic nuclei was most prominent in the Congo grey parrot, both in the medial and lateral hypothalamus. In contrast, no evidence of cholinergic neurons in the hypothalami of either the ostrich or emu was found. It is known that the expression of sleep states in the ostrich is unusual and resembles that observed in the monotremes that also lack hypothalamic cholinergic neurons. It has been proposed that the cholinergic system acts globally to produce and maintain brain states, such as those of arousal and rapid-eye-movement sleep. The hiatus in the cholinergic system of the ostrich, due to the lack of hypothalamic cholinergic neurons, may explain, in part, the unusual expression of sleep states in this species. These comparative anatomical and sleep studies provide supportive evidence for global cholinergic actions and may provide an important framework for our understanding of one broad function of the cholinergic system and possible dysfunctions associated with global cholinergic neural activity.
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Affiliation(s)
- Pedzisai Mazengenya
- College of Medicine, Ajman University, Ajman, United Arab Emirates
- Center of Medical and Bio-allied Health Sciences Research, Ajman University, Ajman, United Arab Emirates
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, Republic of South Africa
| | - John A Lesku
- Sleep Ecophysiology Group, School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia
| | - Niels C Rattenborg
- Avian Sleep Group, Max Planck Institute for Biological Intelligence, Seewiesen, Germany
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Johannesburg, Republic of South Africa
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2
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Whyland KL, Hernandez Y, Slusarczyk AS, Guido W, Bickford ME. The parabigeminal nucleus is a source of "retinogeniculate replacement terminals" in mice that lack retinofugal input. J Comp Neurol 2022; 530:3179-3192. [PMID: 36066425 PMCID: PMC9588688 DOI: 10.1002/cne.25401] [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: 06/09/2022] [Revised: 07/26/2022] [Accepted: 08/09/2022] [Indexed: 11/06/2022]
Abstract
In the dorsal lateral geniculate nucleus (LGN) of mice that lack retinal input, a population of large terminals supplants the synaptic arrangements normally made by the missing retinogeniculate terminals. To identify potential sources of these "retinogeniculate replacement terminals," we used mutant mice (math5-/- ) which lack retinofugal projections due to the failure of retinal ganglion cells to develop. In this line, we labeled LGN terminals that originate from the primary visual cortex (V1) or the parabigeminal nucleus (PBG), and compared their ultrastructure to retinogeniculate, V1 or PBG terminals in the dLGN of C57Blk6 (WT) mice (schematically depicted above graph). Corticogeniculate terminals labeled in WT and math5-/- mice were similar in size and both groups were significantly smaller than WT retinogeniculate terminals. In contrast, the PBG projection in math5-/- mice was extensive and there was considerable overlap in the sizes of retinogeniculate terminals in WT mice and PBG terminals in math5-/- mice (summarized in histogram). The data indicate that V1 is not a source of "retinogeniculate replacement terminals" and suggests that large PBG terminals expand their innervation territory to replace retinogeniculate terminals in their absence.
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Affiliation(s)
- Kyle L. Whyland
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292
| | - Yanio Hernandez
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292
| | - Arkadiusz S. Slusarczyk
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292
| | - William Guido
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292
| | - Martha E. Bickford
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292
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3
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Reyes-Pinto R, Ferrán JL, Vega-Zuniga T, González-Cabrera C, Luksch H, Mpodozis J, Puelles L, Marín GJ. Change in the neurochemical signature and morphological development of the parvocellular isthmic projection to the avian tectum. J Comp Neurol 2021; 530:553-573. [PMID: 34363623 DOI: 10.1002/cne.25229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/27/2021] [Accepted: 07/30/2021] [Indexed: 11/05/2022]
Abstract
Neurons can change their classical neurotransmitters during ontogeny, sometimes going through stages of dual release. Here, we explored the development of the neurotransmitter identity of neurons of the avian nucleus isthmi parvocellularis (Ipc), whose axon terminals are retinotopically arranged in the optic tectum (TeO) and exert a focal gating effect upon the ascending transmission of retinal inputs. Although cholinergic and glutamatergic markers are both found in Ipc neurons and terminals of adult pigeons and chicks, the mRNA expression of the vesicular acetylcholine transporter, VAChT, is weak or absent. To explore how the Ipc neurotransmitter identity is established during ontogeny, we analyzed the expression of mRNAs coding for cholinergic (ChAT, VAChT, and CHT) and glutamatergic (VGluT2 and VGluT3) markers in chick embryos at different developmental stages. We found that between E12 and E18, Ipc neurons expressed all cholinergic mRNAs and also VGluT2 mRNA; however, from E16 through posthatch stages, VAChT mRNA expression was specifically diminished. Our ex vivo deposits of tracer crystals and intracellular filling experiments revealed that Ipc axons exhibit a mature paintbrush morphology late in development, experiencing marked morphological transformations during the period of presumptive dual vesicular transmitter release. Additionally, although ChAT protein immunoassays increasingly label the growing Ipc axon, this labeling was consistently restricted to sparse portions of the terminal branches. Combined, these results suggest that the synthesis of glutamate and acetylcholine, and their vesicular release, is complexly linked to the developmental processes of branching, growing and remodeling of these unique axons.
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Affiliation(s)
- Rosana Reyes-Pinto
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - José L Ferrán
- Department of Human Anatomy and Psychobiology and IMIB-Arrixaca Institute, University of Murcia, Murcia, Spain
| | - Tomas Vega-Zuniga
- Lehrstuhl für Zoologie, Technical University of Munich, Freising, Germany.,Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | | | - Harald Luksch
- Lehrstuhl für Zoologie, Technical University of Munich, Freising, Germany
| | - Jorge Mpodozis
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology and IMIB-Arrixaca Institute, University of Murcia, Murcia, Spain
| | - Gonzalo J Marín
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.,Facultad de Medicina, Universidad Finis Terrae, Santiago, Chile
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4
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Fernández M, Reyes-Pinto R, Norambuena C, Sentis E, Mpodozis J. A canonical interlaminar circuit in the sensory dorsal ventricular ridge of birds: The anatomical organization of the trigeminal pallium. J Comp Neurol 2021; 529:3410-3428. [PMID: 34176123 DOI: 10.1002/cne.25201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 06/08/2021] [Accepted: 06/21/2021] [Indexed: 12/19/2022]
Abstract
The dorsal ventricular ridge (DVR), which is the largest component of the avian pallium, contains discrete partitions receiving tectovisual, auditory, and trigeminal ascending projections. Recent studies have shown that the auditory and the tectovisual regions can be regarded as complexes composed of three highly interconnected layers: an internal senso-recipient one, an intermediate afferent/efferent one, and a more external re-entrant one. Cells located in homotopic positions in each of these layers are reciprocally linked by an interlaminar loop of axonal processes, forming columnar-like local circuits. Whether this type of organization also extends to the trigemino-recipient DVR is, at present, not known. This question is of interest, since afferents forming this sensory pathway, exceptional among amniotes, are not thalamic but rhombencephalic in origin. We investigated this question by placing minute injections of neural tracers into selected locations of vital slices of the chicken telencephalon. We found that neurons of the trigemino-recipient nucleus basorostralis pallii (Bas) establish reciprocal, columnar and homotopical projections with cells located in the overlying ventral mesopallium (MV). "Column-forming" axons originated in B and MV terminate also in the intermediate strip, the fronto-trigeminal nidopallium (NFT), in a restricted manner. We also found that the NFT and an internal partition of B originate substantial, coarse-topographic projections to the underlying portion of the lateral striatum. We conclude that all sensory areas of the DVR are organized according to a common neuroarchitectonic motif, which bears a striking resemblance to that of the radial/laminar intrinsic circuits of the sensory cortices of mammals.
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Affiliation(s)
- Máximo Fernández
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Rosana Reyes-Pinto
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Carolina Norambuena
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Elisa Sentis
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Jorge Mpodozis
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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5
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Deichler A, Carrasco D, Lopez-Jury L, Vega-Zuniga T, Márquez N, Mpodozis J, Marín GJ. A specialized reciprocal connectivity suggests a link between the mechanisms by which the superior colliculus and parabigeminal nucleus produce defensive behaviors in rodents. Sci Rep 2020; 10:16220. [PMID: 33004866 PMCID: PMC7530999 DOI: 10.1038/s41598-020-72848-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 08/06/2020] [Indexed: 12/22/2022] Open
Abstract
The parabigeminal nucleus (PBG) is the mammalian homologue to the isthmic complex of other vertebrates. Optogenetic stimulation of the PBG induces freezing and escape in mice, a result thought to be caused by a PBG projection to the central nucleus of the amygdala. However, the isthmic complex, including the PBG, has been classically considered satellite nuclei of the Superior Colliculus (SC), which upon stimulation of its medial part also triggers fear and avoidance reactions. As the PBG-SC connectivity is not well characterized, we investigated whether the topology of the PBG projection to the SC could be related to the behavioral consequences of PBG stimulation. To that end, we performed immunohistochemistry, in situ hybridization and neural tracer injections in the SC and PBG in a diurnal rodent, the Octodon degus. We found that all PBG neurons expressed both glutamatergic and cholinergic markers and were distributed in clearly defined anterior (aPBG) and posterior (pPBG) subdivisions. The pPBG is connected reciprocally and topographically to the ipsilateral SC, whereas the aPBG receives afferent axons from the ipsilateral SC and projected exclusively to the contralateral SC. This contralateral projection forms a dense field of terminals that is restricted to the medial SC, in correspondence with the SC representation of the aerial binocular field which, we also found, in O. degus prompted escape reactions upon looming stimulation. Therefore, this specialized topography allows binocular interactions in the SC region controlling responses to aerial predators, suggesting a link between the mechanisms by which the SC and PBG produce defensive behaviors.
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Affiliation(s)
- Alfonso Deichler
- Laboratorio de Neurobiología Y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras, 3425, Santiago, Chile.
| | - Denisse Carrasco
- Laboratorio de Neurobiología Y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras, 3425, Santiago, Chile
| | - Luciana Lopez-Jury
- Laboratorio de Neurobiología Y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras, 3425, Santiago, Chile
| | - Tomas Vega-Zuniga
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Natalia Márquez
- Laboratorio de Neurobiología Y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras, 3425, Santiago, Chile
| | - Jorge Mpodozis
- Laboratorio de Neurobiología Y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras, 3425, Santiago, Chile
| | - Gonzalo J Marín
- Laboratorio de Neurobiología Y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras, 3425, Santiago, Chile.
- Facultad de Medicina, Universidad Finis Terrae, Santiago, Chile.
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6
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Entrainment within neuronal response in optic tectum of pigeon to video displays. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2020; 206:845-855. [PMID: 32809044 DOI: 10.1007/s00359-020-01442-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 07/28/2020] [Accepted: 08/03/2020] [Indexed: 12/19/2022]
Abstract
The cathode ray tube (CRT) is a common and important tool that has been in use for decades, with which behavioral and visual neuroscientists deliver specific visual images generated by computers. Considering the operating principle of the CRT, the image it presents can flick at a constant rate, which will introduce distractions to the visual experiments on subjects with higher temporal resolutions. While this entrainment has been proved common in recordings of the primary visual cortex of mammals, it is uncertain whether it also exists in the intermediate to deep layers of pigeon's optic tectum, which is relevant to the spatial attention. Here, we present continuous visual stimuli with different refresh rates and luminances couples shown on a CRT to pigeons. The recordings in the intermediate to deep layers of optic tectum were significantly phase locking to the refresh of the CRT, and lower refresh rates of the CRT with higher brightness more likely introduced artifacts in electrophysiological recordings of pigeons, which may seriously damage their visual information perception.
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7
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Deichler A, Carrasco D, Gonzalez-Cabrera C, Letelier JC, Marín G, Mpodozis J. The nucleus pretectalis principalis: A pretectal structure hidden in the mammalian thalamus. J Comp Neurol 2018; 527:372-391. [DOI: 10.1002/cne.24540] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 08/29/2018] [Accepted: 09/12/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Alfonso Deichler
- Departamento de Biología, Facultad de Ciencias; Universidad de Chile; Ñuñoa Chile
| | - Denisse Carrasco
- Departamento de Biología, Facultad de Ciencias; Universidad de Chile; Ñuñoa Chile
| | - Cristian Gonzalez-Cabrera
- Departamento de Anatomía, Escuela de Medicina; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Juan C. Letelier
- Departamento de Biología, Facultad de Ciencias; Universidad de Chile; Ñuñoa Chile
| | - Gonzalo Marín
- Departamento de Biología, Facultad de Ciencias; Universidad de Chile; Ñuñoa Chile
- Facultad de Medicina; Universidad Finis Terrae; Santiago Chile
| | - Jorge Mpodozis
- Departamento de Biología, Facultad de Ciencias; Universidad de Chile; Ñuñoa Chile
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8
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González-Cabrera C, Meza R, Ulloa L, Merino-Sepúlveda P, Luco V, Sanhueza A, Oñate-Ponce A, Bolam JP, Henny P. Characterization of the axon initial segment of mice substantia nigra dopaminergic neurons. J Comp Neurol 2017; 525:3529-3542. [PMID: 28734032 DOI: 10.1002/cne.24288] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Revised: 07/08/2017] [Accepted: 07/10/2017] [Indexed: 12/11/2022]
Abstract
The axon initial segment (AIS) is the site of initiation of action potentials and influences action potential waveform, firing pattern, and rate. In view of the fundamental aspects of motor function and behavior that depend on the firing of substantia nigra pars compacta (SNc) dopaminergic neurons, we identified and characterized their AIS in the mouse. Immunostaining for tyrosine hydroxylase (TH), sodium channels (Nav ) and ankyrin-G (Ank-G) was used to visualize the AIS of dopaminergic neurons. Reconstructions of sampled AIS of dopaminergic neurons revealed variable lengths (12-60 μm) and diameters (0.2-0.8 μm), and an average of 50% reduction in diameter between their widest and thinnest parts. Ultrastructural analysis revealed submembranous localization of Ank-G at nodes of Ranvier and AIS. Serial ultrathin section analysis and 3D reconstructions revealed that Ank-G colocalized with TH only at the AIS. Few cases of synaptic innervation of the AIS of dopaminergic neurons were observed. mRNA in situ hybridization of brain-specific Nav subunits revealed the expression of Nav 1.2 by most SNc neurons and a small proportion expressing Nav 1.6. The presence of sodium channels, along with the submembranous location of Ank-G is consistent with the role of AIS in action potential generation. Differences in the size of the AIS likely underlie differences in firing pattern, while the tapering diameter of AIS may define a trigger zone for action potentials. Finally, the conspicuous expression of Nav 1.2 by the majority of dopaminergic neurons may explain their high threshold for firing and their low discharge rate.
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Affiliation(s)
- Cristian González-Cabrera
- Laboratorio de Neuroanatomía, Departamento de Anatomía, and Centro Interdisciplinario de Neurociencia, NeuroUC, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rodrigo Meza
- Laboratorio de Neuroanatomía, Departamento de Anatomía, and Centro Interdisciplinario de Neurociencia, NeuroUC, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Lorena Ulloa
- Laboratorio de Neuroanatomía, Departamento de Anatomía, and Centro Interdisciplinario de Neurociencia, NeuroUC, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Paulina Merino-Sepúlveda
- Laboratorio de Neuroanatomía, Departamento de Anatomía, and Centro Interdisciplinario de Neurociencia, NeuroUC, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Valentina Luco
- Laboratorio de Neuroanatomía, Departamento de Anatomía, and Centro Interdisciplinario de Neurociencia, NeuroUC, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Ana Sanhueza
- Laboratorio de Neuroanatomía, Departamento de Anatomía, and Centro Interdisciplinario de Neurociencia, NeuroUC, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alejandro Oñate-Ponce
- Laboratorio de Neuroanatomía, Departamento de Anatomía, and Centro Interdisciplinario de Neurociencia, NeuroUC, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - J Paul Bolam
- MRC Brain Network Dynamics Unit, Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Pablo Henny
- Laboratorio de Neuroanatomía, Departamento de Anatomía, and Centro Interdisciplinario de Neurociencia, NeuroUC, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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9
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Stacho M, Letzner S, Theiss C, Manns M, Güntürkün O. A GABAergic tecto-tegmento-tectal pathway in pigeons. J Comp Neurol 2016; 524:2886-913. [DOI: 10.1002/cne.23999] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 03/10/2016] [Accepted: 03/10/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Martin Stacho
- Department of Biopsychology, Faculty of Psychology, Institute of Cogntive Neuroscience; Ruhr-University Bochum; 44801 Bochum Germany
| | - Sara Letzner
- Department of Biopsychology, Faculty of Psychology, Institute of Cogntive Neuroscience; Ruhr-University Bochum; 44801 Bochum Germany
| | - Carsten Theiss
- Department of Cytology, Faculty of Medicine; Ruhr-University Bochum; 44801 Bochum Germany
| | - Martina Manns
- Department of Biopsychology, Faculty of Psychology, Institute of Cogntive Neuroscience; Ruhr-University Bochum; 44801 Bochum Germany
| | - Onur Güntürkün
- Department of Biopsychology, Faculty of Psychology, Institute of Cogntive Neuroscience; Ruhr-University Bochum; 44801 Bochum Germany
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10
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Atoji Y. Gene expression of ionotropic glutamate receptor subunits in the tectofugal pathway of the pigeon. Neuroscience 2016; 316:367-77. [DOI: 10.1016/j.neuroscience.2015.12.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 12/15/2015] [Accepted: 12/16/2015] [Indexed: 12/19/2022]
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11
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Vega-Zuniga T, Marín G, González-Cabrera C, Planitscher E, Hartmann A, Marks V, Mpodozis J, Luksch H. Microconnectomics of the pretectum and ventral thalamus in the chicken (Gallus gallus). J Comp Neurol 2015; 524:2208-29. [PMID: 26659271 DOI: 10.1002/cne.23941] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 11/23/2015] [Accepted: 11/24/2015] [Indexed: 11/06/2022]
Abstract
The avian pretectal and ventrothalamic nuclei, encompassing the griseum tectale (GT), n. lentiformis mesencephali (LM), and n. geniculatus lateralis pars ventralis (GLv), are prominent retinorecipient structures related to optic flow operations and visuomotor control. Hence, a close coordination of these neural circuits is to be expected. Yet the connectivity among these nuclei is poorly known. Here, using intracellular labeling and in situ hybridization, we investigated the detailed morphology, connectivity, and neurochemical identity of neurons in these nuclei. Two different cell types exist in the GT: one that generates an axonal projection to the optic tectum (TeO), LM, GLv, and n. intercalatus thalami (ICT), and a second population that only projects to the LM and GLv. In situ hybridization revealed that most neurons in the GT express the vesicular glutamate transporter (VGluT2) mRNA, indicating a glutamatergic identity. In the LM, three morphological cell types were defined, two of which project axons towards dorsal targets. The LM neurons showed strong VGluT2 expression. Finally, the cells located in the GLv project to the TeO, LM, GT, n. principalis precommisuralis (PPC), and ICT. All neurons in the GLv showed strong expression of the vesicular inhibitory amino acid transporter (VIAAT) mRNA, suggesting a GABAergic identity. Our results show that the pretectal and ventrothalamic nuclei are highly interconnected, especially by glutamatergic and GABAergic neurons from the GT and GLv, respectively. This complex morphology and connectivity might be required to organize orienting visuomotor behaviors and coordinate the specific optic flow patterns that they induce. J. Comp. Neurol. 524:2208-2229, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Tomas Vega-Zuniga
- Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany
| | - Gonzalo Marín
- Laboratorio de Neurobiología y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.,Facultad de Medicina, Universidad Finis Terrae, Santiago, Chile
| | - Cristian González-Cabrera
- Laboratorio de Neurobiología y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Eva Planitscher
- Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany
| | - Anja Hartmann
- Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany
| | - Vanessa Marks
- Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany
| | - Jorge Mpodozis
- Laboratorio de Neurobiología y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Harald Luksch
- Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany
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12
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González-Cabrera C, Garrido-Charad F, Mpodozis J, Bolam JP, Marín GJ. Axon terminals from the nucleus isthmi pars parvocellularis control the ascending retinotectofugal output through direct synaptic contact with tectal ganglion cell dendrites. J Comp Neurol 2015. [PMID: 26224333 DOI: 10.1002/cne.23860] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The optic tectum in birds and its homologue the superior colliculus in mammals both send major bilateral, nontopographic projections to the nucleus rotundus and caudal pulvinar, respectively. These projections originate from widefield tectal ganglion cells (TGCs) located in layer 13 in the avian tectum and in the lower superficial layers in the mammalian colliculus. The TGCs characteristically have monostratified arrays of brush-like dendritic terminations and respond mostly to bidimensional motion or looming features. In birds, this TGC-mediated tectofugal output is controlled by feedback signals from the nucleus isthmi pars parvocellularis (Ipc). The Ipc neurons display topographically organized axons that densely ramify in restricted columnar terminal fields overlapping various neural elements that could mediate this tectofugal control, including the retinal terminals and the TGC dendrites themselves. Whether the Ipc axons make synaptic contact with these or other tectal neural elements remains undetermined. We double labeled Ipc axons and their presumptive postsynaptic targets in the tectum of chickens (Gallus gallus) with neural tracers and performed an ultrastructural analysis. We found that the Ipc terminal boutons form glomerulus-like structures in the superficial and intermediate tectal layers, establishing asymmetric synapses with several dendritic profiles. In these glomeruli, at least two of the postsynaptic dendrites originated from TGCs. We also found synaptic contacts between retinal terminals and TGC dendrites. These findings suggest that, in birds, Ipc axons control the ascending tectal outflow of retinal signals through direct synaptic contacts with the TGCs.
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Affiliation(s)
- Cristian González-Cabrera
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Región Metropolitana, Chile
| | - Florencia Garrido-Charad
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Región Metropolitana, Chile
| | - Jorge Mpodozis
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Región Metropolitana, Chile
| | - J Paul Bolam
- Medical Research Council Anatomical Neuropharmacology Unit, Department of Pharmacology, University of Oxford, Oxford, OX1 2JA, United Kingdom
| | - Gonzalo J Marín
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Región Metropolitana, Chile.,Facultad de Medicina, Universidad Finis Terrae, Providencia, Santiago, Región Metropolitana, Chile
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