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Araya-Arriagada J, Garay S, Rojas C, Duran-Aniotz C, Palacios AG, Chacón M, Medina LE. Multiscale entropy analysis of retinal signals reveals reduced complexity in a mouse model of Alzheimer's disease. Sci Rep 2022; 12:8900. [PMID: 35614075 PMCID: PMC9132967 DOI: 10.1038/s41598-022-12208-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 05/06/2022] [Indexed: 11/26/2022] Open
Abstract
Alzheimer's disease (AD) is one of the most significant health challenges of our time, affecting a growing number of the elderly population. In recent years, the retina has received increased attention as a candidate for AD biomarkers since it appears to manifest the pathological signatures of the disease. Therefore, its electrical activity may hint at AD-related physiological changes. However, it is unclear how AD affects retinal electrophysiology and what tools are more appropriate to detect these possible changes. In this study, we used entropy tools to estimate the complexity of the dynamics of healthy and diseased retinas at different ages. We recorded microelectroretinogram responses to visual stimuli of different nature from retinas of young and adult, wild-type and 5xFAD-an animal model of AD-mice. To estimate the complexity of signals, we used the multiscale entropy approach, which calculates the entropy at several time scales using a coarse graining procedure. We found that young retinas had more complex responses to different visual stimuli. Further, the responses of young, wild-type retinas to natural-like stimuli exhibited significantly higher complexity than young, 5xFAD retinas. Our findings support a theory of complexity-loss with aging and disease and can have significant implications for early AD diagnosis.
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Affiliation(s)
- Joaquín Araya-Arriagada
- Escuela de Tecnología Médica, Facultad de Salud, Universidad Santo Tomás, Santiago, Chile
- Centro de Investigación e Innovación en Gerontología Aplicada (CIGAP), Facultad de Salud, Universidad Santo Tomás, Antofagasta, Chile
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Sebastián Garay
- Departamento de Ingeniería Informática, Universidad de Santiago de Chile, Santiago, Chile
| | - Cristóbal Rojas
- Instituto de Ingeniería Matemática y Computacional, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Claudia Duran-Aniotz
- Latin American Institute for Brain Health (BrainLat), Universidad Adolfo Ibanez, Santiago, Chile
- Center for Social and Cognitive Neuroscience (CSCN), Universidad Adolfo Ibanez, Santiago, Chile
| | - Adrián G Palacios
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Instituto de Sistemas Complejos de Valparaíso, Valparaíso, Chile
| | - Max Chacón
- Departamento de Ingeniería Informática, Universidad de Santiago de Chile, Santiago, Chile
| | - Leonel E Medina
- Departamento de Ingeniería Informática, Universidad de Santiago de Chile, Santiago, Chile.
- Millennium Nucleus for Applied Control and Inverse Problems, Santiago, Chile.
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2
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Harcha PA, López-López T, Palacios AG, Sáez PJ. Pannexin Channel Regulation of Cell Migration: Focus on Immune Cells. Front Immunol 2022; 12:750480. [PMID: 34975840 PMCID: PMC8716617 DOI: 10.3389/fimmu.2021.750480] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 11/15/2021] [Indexed: 12/12/2022] Open
Abstract
The role of Pannexin (PANX) channels during collective and single cell migration is increasingly recognized. Amongst many functions that are relevant to cell migration, here we focus on the role of PANX-mediated adenine nucleotide release and associated autocrine and paracrine signaling. We also summarize the contribution of PANXs with the cytoskeleton, which is also key regulator of cell migration. PANXs, as mechanosensitive ATP releasing channels, provide a unique link between cell migration and purinergic communication. The functional association with several purinergic receptors, together with a plethora of signals that modulate their opening, allows PANX channels to integrate physical and chemical cues during inflammation. Ubiquitously expressed in almost all immune cells, PANX1 opening has been reported in different immunological contexts. Immune activation is the epitome coordination between cell communication and migration, as leukocytes (i.e., T cells, dendritic cells) exchange information while migrating towards the injury site. In the current review, we summarized the contribution of PANX channels during immune cell migration and recruitment; although we also compile the available evidence for non-immune cells (including fibroblasts, keratinocytes, astrocytes, and cancer cells). Finally, we discuss the current evidence of PANX1 and PANX3 channels as a both positive and/or negative regulator in different inflammatory conditions, proposing a general mechanism of these channels contribution during cell migration.
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Affiliation(s)
- Paloma A Harcha
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Tamara López-López
- Cell Communication and Migration Laboratory, Institute of Biochemistry and Molecular Cell Biology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Adrián G Palacios
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Pablo J Sáez
- Cell Communication and Migration Laboratory, Institute of Biochemistry and Molecular Cell Biology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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3
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Silva A, Tomassini C, Zurbrigg J, Palacios AG, Amarante V, Bouzat C. Gender inequality in Latin American Neuroscience community. IBRO Neurosci Rep 2021; 10:104-108. [PMID: 33842917 PMCID: PMC8019992 DOI: 10.1016/j.ibneur.2021.01.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/28/2021] [Indexed: 11/26/2022] Open
Abstract
Gender bias in Science, Technology, Engineering, and Mathematics (STEM) has been identified since a long time ago. However, gender imbalance in neuroscience has not yet been adequately explored worldwide. Here we report the first study on the development of the careers of men and women neuroscientists in Latin America in relation to family life and their perceptions of obstacles to success. Apart from revealing gender inequality in the neuroscience field, distinctive Latin American traits have become evident, thus providing novel insights into the global comprehension of gender imbalance in the region, which is required for guiding future actions, including the design of public policies in the region.
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Affiliation(s)
- Ana Silva
- Latin American Regional Committee (LARC) of the International Brain Research Organization (IBRO), Uruguay.,Facultad de Ciencias, Universidad de la República, Uruguay
| | - Cecilia Tomassini
- Facultad de Ciencias, Universidad de la República, Uruguay.,Economic Commission for Latin America and the Caribbean in Montevideo, Uruguay
| | - Julieta Zurbrigg
- Economic Commission for Latin America and the Caribbean in Montevideo, Uruguay
| | - Adrián G Palacios
- Latin American Regional Committee (LARC) of the International Brain Research Organization (IBRO), Uruguay.,Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Chile
| | - Verónica Amarante
- Economic Commission for Latin America and the Caribbean in Montevideo, Uruguay
| | - Cecilia Bouzat
- Latin American Regional Committee (LARC) of the International Brain Research Organization (IBRO), Uruguay.,Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur (UNS)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
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4
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Araya-Arriagada J, Bello F, Shivashankar G, Neira D, Durán-Aniotz C, Acosta ML, Escobar MJ, Hetz C, Chacón M, Palacios AG. Retinal Ganglion Cells Functional Changes in a Mouse Model of Alzheimer's Disease Are Linked with Neurotransmitter Alterations. J Alzheimers Dis 2021; 82:S5-S18. [PMID: 33749647 DOI: 10.3233/jad-201195] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Alzheimer's disease (AD) is the most prevalent form of dementia worldwide. This neurodegenerative syndrome affects cognition, memory, behavior, and the visual system, particularly the retina. OBJECTIVE This work aims to determine whether the 5xFAD mouse, a transgenic model of AD, displays changes in the function of retinal ganglion cells (RGCs) and if those alterations are correlated with changes in the expression of glutamate and gamma-aminobutyric acid (GABA) neurotransmitters. METHODS In young (2-3-month-old) and adult (6-7-month-old) 5xFAD and WT mice, we have studied the physiological response, firing rate, and burst of RGCs to various types of visual stimuli using a multielectrode array system. RESULTS The firing rate and burst response in 5xFAD RGCs showed hyperactivity at the early stage of AD in young mice, whereas hypoactivity was seen at the later stage of AD in adults. The physiological alterations observed in 5xFAD correlate well with an increase in the expression of glutamate in the ganglion cell layer in young and adults. GABA staining increased in the inner nuclear and plexiform layer, which was more pronounced in the adult than the young 5xFAD retina, altering the excitation/inhibition balance, which could explain the observed early hyperactivity and later hypoactivity in RGC physiology. CONCLUSION These findings indicate functional changes may be caused by neurochemical alterations of the retina starting at an early stage of the AD disease.
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Affiliation(s)
- Joaquín Araya-Arriagada
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile.,Escuela de Tecnología Médica, Facultad de Salud, Universidad Santo Tomás, Chile
| | - Felipe Bello
- Department of Engineering Informatics, Universidad de Santiago, Santiago, Chile
| | - Gaganashree Shivashankar
- School of Optometry and Vision Science; Centre for Brain Research; Brain Research New Zealand; The University of Auckland, Auckland, New Zealand
| | - David Neira
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Claudia Durán-Aniotz
- Center for Social and Cognitive Neuroscience, School of Psychology, Universidad Adolfo Ibáñez, Santiago de Chile, Chile
| | - Mónica L Acosta
- School of Optometry and Vision Science; Centre for Brain Research; Brain Research New Zealand; The University of Auckland, Auckland, New Zealand
| | - María José Escobar
- Departamento de Electrónica, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - Claudio Hetz
- Biomedical Neuroscience Institute, Universidad de Chile, Santiago, Chile
| | - Max Chacón
- Department of Engineering Informatics, Universidad de Santiago, Santiago, Chile
| | - Adrián G Palacios
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
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5
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Escobar MJ, Reyes C, Herzog R, Araya J, Otero M, Ibaceta C, Palacios AG. Characterization of Retinal Functionality at Different Eccentricities in a Diurnal Rodent. Front Cell Neurosci 2018; 12:444. [PMID: 30559649 PMCID: PMC6287453 DOI: 10.3389/fncel.2018.00444] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 11/05/2018] [Indexed: 11/18/2022] Open
Abstract
Although the properties of the neurons of the visual system that process central and peripheral regions of the visual field have been widely researched in the visual cortex and the LGN, they have scarcely been documented for the retina. The retina is the first step in integrating optical signals, and despite considerable efforts to functionally characterize the different types of retinal ganglion cells (RGCs), a clear account of the particular functionality of cells with central vs. peripheral fields is still wanting. Here, we use electrophysiological recordings, gathered from retinas of the diurnal rodent Octodon degus, to show that RGCs with peripheral receptive fields (RF) are larger, faster, and have shorter transient responses. This translates into higher sensitivity at high temporal frequencies and a full frequency bandwidth when compared to RGCs with more central RF. We also observed that imbalances between ON and OFF cell populations are preserved with eccentricity. Finally, the high diversity of functional types of RGCs highlights the complexity of the computational strategies implemented in the early stages of visual processing, which could inspire the development of bio-inspired artificial systems.
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Affiliation(s)
- María-José Escobar
- Departamento de Electrónica, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - César Reyes
- Departamento de Electrónica, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - Rubén Herzog
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Joaquin Araya
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
- Programa de Doctorado en NeurocienciaUniversidad de Santiago de Chile, Santiago, Chile
| | - Mónica Otero
- Departamento de Electrónica, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - Cristóbal Ibaceta
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Adrián G. Palacios
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
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6
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Salazar C, Valdivia G, Ardiles ÁO, Ewer J, Palacios AG. Genetic variants associated with neurodegenerative Alzheimer disease in natural models. Biol Res 2016; 49:14. [PMID: 26919851 PMCID: PMC4769573 DOI: 10.1186/s40659-016-0072-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 02/12/2016] [Indexed: 01/05/2023] Open
Abstract
The use of transgenic models for the study of neurodegenerative diseases has made valuable contributions to the field. However, some important limitations, including protein overexpression and general systemic compensation for the missing genes, has caused researchers to seek natural models that show the main biomarkers of neurodegenerative diseases during aging. Here we review some of these models-most of them rodents, focusing especially on the genetic variations in biomarkers for Alzheimer diseases, in order to explain their relationships with variants associated with the occurrence of the disease in humans.
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Affiliation(s)
- Claudia Salazar
- Facultad de Ciencia, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile.
| | - Gonzalo Valdivia
- Facultad de Ciencia, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile.
| | - Álvaro O Ardiles
- Facultad de Ciencia, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile.
| | - John Ewer
- Facultad de Ciencia, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile.
| | - Adrián G Palacios
- Facultad de Ciencia, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile. .,Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Pasaje Harrington 287, Playa Ancha, 2360102, Valparaíso, Chile.
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7
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Inestrosa NC, Ríos JA, Cisternas P, Tapia-Rojas C, Rivera DS, Braidy N, Zolezzi JM, Godoy JA, Carvajal FJ, Ardiles AO, Bozinovic F, Palacios AG, Sachdev PS. Age Progression of Neuropathological Markers in the Brain of the Chilean Rodent Octodon degus, a Natural Model of Alzheimer's Disease. Brain Pathol 2015; 25:679-91. [PMID: 25351914 DOI: 10.1111/bpa.12226] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 10/21/2014] [Indexed: 02/06/2023] Open
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disorder and the leading cause of age-related dementia worldwide. Several models for AD have been developed to provide information regarding the initial changes that lead to degeneration. Transgenic mouse models recapitulate many, but not all, of the features of AD, most likely because of the high complexity of the pathology. In this context, the validation of a wild-type animal model of AD that mimics the neuropathological and behavioral abnormalities is necessary. In previous studies, we have reported that the Chilean rodent Octodon degus could represent a natural model for AD. In the present work, we further describe the age-related neurodegeneration observed in the O. degus brain. We report some histopathological markers associated with the onset progression of AD, such as glial activation, increase in oxidative stress markers, neuronal apoptosis and the expression of the peroxisome proliferative-activated receptor γ coactivator-1α (PGC-1α). With these results, we suggest that the O. degus could represent a new model for AD research and a powerful tool in the search for therapeutic strategies against AD.
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Affiliation(s)
- Nibaldo C Inestrosa
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro UC Síndrome de Down, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile.,Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Juvenal A Ríos
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Pedro Cisternas
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Cheril Tapia-Rojas
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Daniela S Rivera
- Departamento de Ecología and Center of Applied Ecology and Sustainability (CAPES), Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Nady Braidy
- Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Juan M Zolezzi
- Departamento de Biología, Facultad de Ciencias, Universidad de Tarapacá, Arica, Chile
| | - Juan A Godoy
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Francisco J Carvajal
- Centro de Envejecimiento y Regeneración (CARE), Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alvaro O Ardiles
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Francisco Bozinovic
- Centro UC Síndrome de Down, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Ecología and Center of Applied Ecology and Sustainability (CAPES), Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Adrián G Palacios
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Perminder S Sachdev
- Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia.,Neurosychiatric Institute, Prince of Wales Hospital, Randwick, New South Wales, Australia
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8
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Vielma AH, Agurto A, Valdés J, Palacios AG, Schmachtenberg O. Nitric oxide modulates the temporal properties of the glutamate response in type 4 OFF bipolar cells. PLoS One 2014; 9:e114330. [PMID: 25463389 PMCID: PMC4252109 DOI: 10.1371/journal.pone.0114330] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 11/06/2014] [Indexed: 11/19/2022] Open
Abstract
Nitric oxide (NO) is involved in retinal signal processing, but its cellular actions are only partly understood. An established source of retinal NO are NOACs, a group of nNOS-expressing amacrine cells which signal onto bipolar, other amacrine and ganglion cells in the inner plexiform layer. Here, we report that NO regulates glutamate responses in morphologically and electrophysiologically identified type 4 OFF cone bipolar cells through activation of the soluble guanylyl cyclase-cGMP-PKG pathway. The glutamate response of these cells consists of two components, a fast phasic current sensitive to kainate receptor agonists, and a secondary component with slow kinetics, inhibited by AMPA receptor antagonists. NO shortened the duration of the AMPA receptor-dependent component of the glutamate response, while the kainate receptor-dependent component remained unchanged. Application of 8-Br-cGMP mimicked this effect, while inhibition of soluble guanylate cyclase or protein kinase G prevented it, supporting a mechanism involving a cGMP signaling pathway. Notably, perfusion with a NOS-inhibitor prolonged the duration of the glutamate response, while the NO precursor L-arginine shortened it, in agreement with a modulation by endogenous NO. Furthermore, NO accelerated the response recovery during repeated stimulation of type 4 cone bipolar cells, suggesting that the temporal response properties of this OFF bipolar cell type are regulated by NO. These results reveal a novel cellular mechanism of NO signaling in the retina, and represent the first functional evidence of NO modulating OFF cone bipolar cells.
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Affiliation(s)
- Alex H. Vielma
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
- * E-mail:
| | - Adolfo Agurto
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Joaquín Valdés
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Adrián G. Palacios
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Oliver Schmachtenberg
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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9
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Vega-Zuniga T, Medina FS, Fredes F, Zuniga C, Severín D, Palacios AG, Karten HJ, Mpodozis J. Does nocturnality drive binocular vision? Octodontine rodents as a case study. PLoS One 2013; 8:e84199. [PMID: 24391911 PMCID: PMC3877236 DOI: 10.1371/journal.pone.0084199] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 11/12/2013] [Indexed: 11/25/2022] Open
Abstract
Binocular vision is a visual property that allows fine discrimination of in-depth distance (stereopsis), as well as enhanced light and contrast sensitivity. In mammals enhanced binocular vision is structurally associated with a large degree of frontal binocular overlap, the presence of a corresponding retinal specialization containing a fovea or an area centralis, and well-developed ipsilateral retinal projections to the lateral thalamus (GLd). We compared these visual traits in two visually active species of the genus Octodon that exhibit contrasting visual habits: the diurnal Octodon degus, and the nocturnal Octodon lunatus. The O. lunatus visual field has a prominent 100° frontal binocular overlap, much larger than the 50° of overlap found in O. degus. Cells in the retinal ganglion cell layer were 40% fewer in O. lunatus (180,000) than in O. degus (300,000). O. lunatus has a poorly developed visual streak, but a well developed area centralis, located centrally near the optic disk (peak density of 4,352 cells/mm2). O. degus has a highly developed visual streak, and an area centralis located more temporally (peak density of 6,384 cells/mm2). The volumes of the contralateral GLd and superior colliculus (SC) are 15% larger in O. degus compared to O. lunatus. However, the ipsilateral projections to GLd and SC are 500% larger in O. lunatus than in O. degus. Other retinorecipient structures related to ocular movements and circadian activity showed no statistical differences between species. Our findings strongly suggest that nocturnal visual behavior leads to an enhancement of the structures associated with binocular vision, at least in the case of these rodents. Expansion of the binocular visual field in nocturnal species may have a beneficial effect in light and contrast sensitivity, but not necessarily in stereopsis. We discuss whether these conclusions can be extended to other mammalian and non-mammalian amniotes.
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Affiliation(s)
- Tomas Vega-Zuniga
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Felipe S. Medina
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Felipe Fredes
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Claudio Zuniga
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Daniel Severín
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Adrián G. Palacios
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Harvey J. Karten
- Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Jorge Mpodozis
- Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
- * E-mail:
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10
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Escobar MJ, Palacios AG. Beyond the retina neural coding: on models and neural rehabilitation. ACTA ACUST UNITED AC 2013; 107:335-7. [PMID: 23994100 DOI: 10.1016/j.jphysparis.2013.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- María-José Escobar
- Universidad Técnica Federico Santa María, Departmento de Electronica, 2390123 Valparaíso, Chile.
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Vasquez JC, Marre O, Palacios AG, Berry MJ, Cessac B. Gibbs distribution analysis of temporal correlations structure in retina ganglion cells. ACTA ACUST UNITED AC 2011; 106:120-7. [PMID: 22115900 DOI: 10.1016/j.jphysparis.2011.11.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2011] [Revised: 09/24/2011] [Accepted: 11/03/2011] [Indexed: 11/18/2022]
Abstract
We present a method to estimate Gibbs distributions with spatio-temporal constraints on spike trains statistics. We apply this method to spike trains recorded from ganglion cells of the salamander retina, in response to natural movies. Our analysis, restricted to a few neurons, performs more accurately than pairwise synchronization models (Ising) or the 1-time step Markov models (Marre et al., 2009) to describe the statistics of spatio-temporal spike patterns and emphasizes the role of higher order spatio-temporal interactions.
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Affiliation(s)
- J C Vasquez
- NeuroMathComp Team, INRIA, ENS Paris, UNSA LJAD, 2004 Route des Lucioles, 06902 Sophia-Antipolis, France.
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Muñoz PC, Aspé MA, Contreras LS, Palacios AG. Correlations of recognition memory performance with expression and methylation of brain-derived neurotrophic factor in rats. Biol Res 2010; 43:251-258. [PMID: 21031270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023] Open
Abstract
Object recognition memory allows discrimination between novel and familiar objects. This kind of memory consists of two components: recollection, which depends on the hippocampus, and familiarity, which depends on the perirhinal cortex (Pcx). The importance of brain-derived neurotrophic factor (BDNF) for recognition memory has already been recognized. Recent evidence suggests that DNA methylation regulates the expression of BDNF and memory. Behavioral and molecular approaches were used to understand the potential contribution of DNA methylation to recognition memory. To that end, rats were tested for their ability to distinguish novel from familiar objects by using a spontaneous object recognition task. Furthermore, the level of DNA methylation was estimated after trials with a methyl-sensitive PCR. We found a significant correlation between performance on the novel object task and the expression of BDNF, negatively in hippocampal slices and positively in perirhinal cortical slices. By contrast, methylation of DNA in CpG island 1 in the promoter of exon 1 in BDNF only correlated in hippocampal slices, but not in the Pxc cortical slices from trained animals. These results suggest that DNA methylation may be involved in the regulation of the BDNF gene during recognition memory, at least in the hippocampus.
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Affiliation(s)
- Pablo C Muñoz
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Chile.
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Palacios AG, Bozinovic F, Vielma A, Arrese CA, Hunt DM, Peichl L. Retinal photoreceptor arrangement, SWS1 and LWS opsin sequence, and electroretinography in the South American marsupial Thylamys elegans (Waterhouse, 1839). J Comp Neurol 2010; 518:1589-602. [PMID: 20187149 DOI: 10.1002/cne.22292] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We studied the retinal photoreceptors in the mouse opossum Thylamys elegans, a nocturnal South American marsupial. A variety of photoreceptor properties and color vision capabilities have been documented in Australian marsupials, and we were interested to establish what similarities and differences this American marsupial showed. Thylamys opsin gene sequencing revealed two cone opsins, a longwave-sensitive (LWS) opsin and a shortwave-sensitive (SWS1) opsin with deduced peak sensitivities at 560 nm and 360 nm (ultraviolet), respectively. Immunocytochemistry located these opsins to separate cone populations, a majority of LWS cones (density range 1,600-5,600/mm(2)) and a minority of SWS1 cones (density range 100-690/mm(2)). With rod densities of 440,000-590,000/mm(2), the cones constituted 0.4-1.2% of the photoreceptors. This is a suitable adaptation to nocturnal vision. Cone densities peaked in a horizontally elongated region ventral to the optic nerve head. In ventral-but not dorsal-retina, roughly 40% of the LWS opsin-expressing cones occurred as close pairs (double cones), and one member of each double cone contained a colorless oil droplet. The corneal electroretinogram (ERG) showed a high scotopic sensitivity with a rod peak sensitivity at 505 nm. At mesopic light levels, the spectral ERG revealed the contributions of a UV-sensitive SWS1 cone mechanism and an LWS cone mechanism with peak sensitivities at 365 nm and 555 nm, respectively, confirming the tuning predictions from the cone opsin sequences. The two spectral cone types provide the basis for dichromatic color vision, or trichromacy if the rods contribute to color processing at mesopic light levels.
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Affiliation(s)
- Adrián G Palacios
- Centro de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2370006, Chile
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Martínez-Harms J, Palacios AG, Márquez N, Estay P, Arroyo MTK, Mpodozis J. Can red flowers be conspicuous to bees? Bombus dahlbomii and South American temperate forest flowers as a case in point. ACTA ACUST UNITED AC 2010; 213:564-71. [PMID: 20118307 DOI: 10.1242/jeb.037622] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
It has been argued that trichromatic bees with photoreceptor spectral sensitivity peaks in the ultraviolet (UV), blue and green areas of the spectrum are blind to long wavelengths (red to humans). South American temperate forests (SATF) contain a large number of human red-looking flowers that are reported to be visited by the bumblebee Bombus dahlbomii. In the present study, B. dahlbomii's spectral sensitivity was measured through electroretinogram (ERG) recordings. No extended sensitivity to long wavelengths was found in B. dahlbomii. The spectral reflectance curves from eight plant species with red flowers were measured. The color loci occupied by these flowers in the bee color space was evaluated using the receptor noise-limited model. Four of the plant species have pure red flowers with low levels of chromatic contrast but high levels of negative L-receptor contrast. Finally, training experiments were performed in order to assess the role of achromatic cues in the detection and discrimination of red targets by B. dahlbomii. The results of the training experiments suggest that the bumblebee relies on achromatic contrast provided by the L-receptor to detect and discriminate red targets. These findings are discussed in the context of the evolutionary background under which the relationship between SATF species and their flower visitors may have evolved.
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Affiliation(s)
- J Martínez-Harms
- Instituto de Ecología y Biodiversidad (IEB), Departamento de Ciencias Ecológicas, Universidad de Chile, Santiago, Chile.
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Muñoz PC, Aspé MA, Contreras LS, Palacios AG. Correlations of recognition memory performance with expression and methylation of brain-derived neurotrophic factor in rats. Biol Res 2010. [DOI: 10.4067/s0716-97602010000200013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Delgado LM, Vielma AH, Kähne T, Palacios AG, Schmachtenberg O. The GABAergic system in the retina of neonate and adult Octodon degus, studied by immunohistochemistry and electroretinography. J Comp Neurol 2009; 514:459-72. [PMID: 19350652 DOI: 10.1002/cne.22023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
UNLABELLED In the vertebrate retina, gamma-aminobutyric acid (GABA) mediates inhibitory processes that shape the visual response and is also thought to have neurotrophic functions during retinal development. To investigate the role of GABAergic signaling at the beginning of visual experience, we used immunohistochemistry to compare the distribution of GABA, the two isoforms of glutamic acid decarboxylase GAD65/67, and the GABA receptor types A, B, and C, in neonate versus adult Octodon degus, a native South American rodent with diurnal-crepuscular activity and a high cone-to-rod ratio. In parallel, we used electroretinography to evaluate retinal functionality and to test the contribution of fast GABAergic transmission to light responses at both developmental stages. Neonate O. degus opened their eyes on postnatal day (P)0 and displayed an adult-like retinal morphology at this time. GABA, its biosynthetic sources, and receptors had a similar cellular distribution in neonates and adults, but labeling of the outer plexiform layer and of certain amacrine and ganglion cells was more conspicuous at P0. In neonates, retinal sensitivity was 10 times lower than in adults, responses to ultraviolet light could not be detected, and oscillatory potentials were reduced or absent. Blockade of GABA(A/C) receptors by bicuculline and TPMPA had no noticeable effect in neonates, while it significantly altered the electroretinogram response in adults. CONCLUSION In spite of modest differences regarding retinal morphology and GABAergic expression, overall light response properties and GABAergic signaling are undeveloped in neonate O. degus compared to adults, suggesting that full retinal functionality requires a period of neural refinement under visual experience.
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Affiliation(s)
- Luz M Delgado
- Centro de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Chile
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Abstract
We present a numerical model to fit the electroretinogram (ERG), a gross evoked eye visual potential, that originate in the retina through photons absorption by photoreceptors and then involve the contribution form others retinal neurons. We use the ERG measured in a hummingbird, to evaluate the most likely retinal mechanism - cones visual pigments and oil-droplets - that participate in their high dimensional tetra or pentachromatic color hyperspace. The model - a nonlinear fit - appears to be a very useful tool to predict the underlying contribution visual mechanism for a variety of retinal preparation.
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Affiliation(s)
- M Curé
- Departamento de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Chile
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Cosmelli D, Palacios AG. Networks in cognitive systems and biomedicine: cerebral processes, models and mathematical tools design. Biol Res 2008; 40:381-384. [PMID: 18575673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
Abstract
Convergence of clinical, empirical, methodological and theoretical approaches aimed at understanding the relation between brain function and cognition, is by now standard in most if not all academic programs in the area of Cognitive Science. This confederation of disciplines is one of the liveliest domains of inquiry and discussion into some of the most fundamental--and historically resilient--questions human beings have posed themselves. The contributions gathered in this special issue of Biological Research, directly inspired by the ongoing work at the Instituto de Sistemas Complejos de Valparaiso and the December 2006 CONICYT-INSERM-SFI workshop "Networks in Cognitive Systems/Trends and Challenge in Biomedicine: From Cerebral Process to Mathematical Tools Design", Chile, represent an explicit invitation to the reader to dive deeper into this fascinating terrain.
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Affiliation(s)
- Diego Cosmelli
- Instituto de Sistemas Complejos de Valparaíso, Valparaíso, Chile.
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Goles E, Palacios AG. Dynamical complexity in cognitive neural networks. Biol Res 2008; 40:479-485. [PMID: 18575680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
Abstract
In the last twenty years an important effort in brain sciences, especially in cognitive science, has been the development of mathematical tool that can deal with the complexity of extensive recordings corresponding to the neuronal activity obtained from hundreds of neurons. We discuss here along with some historical issues, advantages and limitations of Artificial Neural Networks (ANN) that can help to understand how simple brain circuits work and whether ANN can be helpful to understand brain neural complexity.
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Affiliation(s)
- Eric Goles
- Instituto de Sistemas Complejos de Valparaíso, Valparaíso, Chile.
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Ocampo-Garcés A, Hernández F, Mena W, Palacios AG. Wheel-running and rest activity pattern interaction in two octodontids (Octodon degus, Octodon bridgesi). Biol Res 2006; 38:299-305. [PMID: 16238108 DOI: 10.4067/s0716-97602005000200019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Wheel-running and other non-photic stimuli influence the rest-activity pattern of diurnal and nocturnal mammals. A day to night inversion of phase preference of activity was described among Octodon degus, when exposed to ad-libitum wheel running. We have studied the rest-activity pattern response in presence of ad libitum wheel-running in wild-captured male individuals from two species of genus Octodon: O. degus (n = 9, crepuscular-diurnal) and O. bridgesi (n = 3, nocturnal). After two months of habituation to laboratory conditions, recordings were performed in isolation chambers under a 12:12 light-dark schedule with or without access to a running wheel. Actograms were constructed from data obtained by an automated acquisition system. O. bridgesi were also recorded under constant darkness, with or without access to wheel-running. Entrained to the light-dark schedule, a crepuscular pattern of activity was evident for O. degus, whereas O. bridgesi displayed a robust nocturnal chronotype. The activity of O. degus observed during the dark phase was enhanced when wheel-running was allowed. No significant change in phase preference was observed for O. bridgesi when wheel-running was allowed. A lengthening of endogenous period was observed in O. bridgesi after wheel-running exposure under constant darkness. Nocturnal and diurnal octodontids exhibit different masking responses to wheel-running.
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Abstract
Rest activity pattern was studied in wild-captured males of Octodon degus (n=9), Octodon bridgesi (n=3), and Spalacopus cyanus (n=6) (Rodentia: Octodontidae). Ten-minute resolution actograms were constructed from data obtained by an automated acquisition system. After two months of habituation to a stable light-dark schedule, recordings were performed in isolation chambers under a 12: 12 Light Dark schedule. A free-running period (constant darkness) was recorded for O. bridgesi and S. cyanus. O. degus displayed a crepuscular pattern of rest activity rhythm. Entrained O. bridgesi and S. cyanus displayed nocturnal preference, with rest anticipating light phase and without crepuscular activity bouts. Under constant darkness, active phase occurred at subjective night in O. bridgesi and S. cyanus. Wild-captured O. bridgesi and S. cyanus possess a circadian driven nocturnal preference, while wild O. degus displays a crepuscular profile. Diurnal active phase preference of wild S. cyanus colonies observed in the field could not be explained solely by photic entrainment, since social and/or masking processes appear to be operative. The genus Octodon includes species with diverse chronotypes. We propose that crepuscular diurnal pattern observed in O. degus is a recent acquisition among the octodontid lineage.
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Chávez AE, Pannicke T, Roncagliolo M, Reichenbach A, Palacios AG. Electrophysiological properties of retinal Müller glial cells from myelin mutant rat. Glia 2003; 45:338-45. [PMID: 14966865 DOI: 10.1002/glia.10330] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The structural and functional similarities between Müller cells and oligodendrocytes prompted the present study of the electrophysiological properties of Müller (glia) cells obtained from the retinae of control and myelin mutant taiep rats during the postnatal developmental period (P12-P180). The whole-cell configuration of the patch-clamp technique was used to characterize the general properties and the K+ currents from dissociated Müller cells. During the first 3 weeks of life, a decrease of the membrane resistance and an increase of the membrane potential were observed in Müller cells from both control and taiep rats. However, Müller cells from taiep rats never achieved the very negative membrane potential (-50 mV vs -80 mV) and the low membrane resistance characteristic for control cells. Furthermore, Müller cells displayed increased inward and outward K+ currents during postnatal development up to P30/60 in controls; however, in taiep rats, this increase ceased at P20/30, and low-amplitude currents persisted into adulthood. These results provide first evidence of physiological changes in retinal Müller cells as a consequence of a myelin mutation causing a progressive deterioration of the central nervous system (CNS) due to a disturbance of the microtubule network of oligodendrocytes. We hypothesize that the progressive dysmyelination process of the optic nerve, accompanied by functional deficits of retinal neurons (e.g., ganglion cells), induces physiological alterations of Müller cells.
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Affiliation(s)
- Andrés E Chávez
- Department of Physiology, Faculty of Science, Neuroscience Center of Valparaiso, University of Valparaíso, Valparaíso, Chile
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Palacios AG, Bacigalupo J. Francisco Varela (1946-2001): filling the mind--brain gap: a life adventure. Biol Res 2003; 36:9-12. [PMID: 12795203 DOI: 10.4067/s0716-97602003000100002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
One of the most eminent neuroscientists recently passed away in Paris. Professor Francisco Varela was a scholar that approached science with a remarkably broad and integrative perspective, deeply contributing to a diversity of fields, from mathematics to epistemology, from immunology to neuroscience. He was strongly influenced by Buddhism and actively participated in unraveling the relationship between science and spirituality. This article introduces a special edition of Biological Research dedicated to the memory of this great man. It contains a collection of valuable contributions by various authors who collaborated with Varela at different moments of his outstanding scientific career. Their articles cover most of the fields in which he made contributions.
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Affiliation(s)
- Adrián G Palacios
- Centro de Neurociencias de Valparaíso (CNV), Departamento de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.
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Chávez AE, Bozinovic F, Peichl L, Palacios AG. Retinal spectral sensitivity, fur coloration, and urine reflectance in the genus octodon (rodentia): implications for visual ecology. Invest Ophthalmol Vis Sci 2003; 44:2290-6. [PMID: 12714673 DOI: 10.1167/iovs.02-0670] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To determine the eye's spectral sensitivity in three species of the genus Octodon (order Rodentia; infraorder Caviomorpha), O. degus, O. bridgesi, and O. lunatus, as well as the spectral properties of the animals' fur and urine and of objects in their habitat. The genus is endemic in Chile and contains species with different habitats and circadian patterns (diurnal versus nocturnal). METHODS The electroretinogram (ERG) was used to record scotopic and photopic spectral sensitivity. The reflectance of ventral and dorsal body parts, urine, and other objects from the natural microhabitat were measured with a fiber-optic spectrometer. RESULTS In scotopic conditions, the maxima of sensitivity (lambda(max)) were at 505.7 +/- 7.7 nm in O. degus, 501 +/- 7.4 nm in O. bridgesi, and 510.1 +/- 7.4 nm in O. lunatus, representing the rod mechanism. In photopic conditions, only the diurnal species O. degus (common degu) was studied. The degu's photopic sensitivity had a lambda(max) at 500.6 +/- 1.2 nm and contained two cone mechanisms with lambda(max) at 500 nm (green, medium-wavelength-sensitive [M] cones) and approximately 360 nm (ultraviolet, short-wavelength-sensitive [S] cones). In all three Octodon species, dorsal body parts were more cryptically colored than ventral ones, and ventral body parts had a significant UV reflectance. The fresh urine of O. degus, used for scent marking in various behavioral patterns, was also high in UV reflectance. CONCLUSIONS It is suggested that territorial urine marks are visual as well as pheromone cues for UV-sensitive species and hence may have favored the evolution of UV-cones in rodents.
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Affiliation(s)
- Andrés E Chávez
- Department of Physiology, Faculty of Science and Center of Molecular and Cellular Neuroscience of Valparaíso, University of Valparaíso, Valparaíso, Chile
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Abstract
PURPOSE To study the histology and the physiological function of the retina in the neurological myelin mutant, taiep rats during the postnatal developmental period (P20-P360). METHODS Electroretinography (ERG) was applied to evaluate intensity dependence and spectral sensitivity of the responses to light. Retinal histology, morphometry, and immunocytochemistry were used to characterize the structure of the retina, with particular emphasis on the Müller (glial) cells. RESULTS In the taiep rats of all ages studied, the scotopic ERG showed normal a- and b-wave amplitudes and latencies; likewise, the scotopic spectral sensitivity function was the same for control and taiep animals, with a maximal sensitivity (lambda(max)) at 500 nm. However, in adult taiep rats (P90 to P360) a secondary cornea-positive wave ('b(2)') was observed in response to high stimulus intensities, which never occurred in controls. This correlated with the observation that in the photopic ERG responses of the taiep rats, the b-wave was reduced in amplitude, and was followed by a rapid cornea-negative after-potential. After 1 year of life, in taiep rats the outer plexiform layer (OPL) became slightly thinner and the inner plexiform/ganglion cell layers (IPL/GCL) appeared to be swollen, and increased in thickness; in addition, the number of retinal neurons (particularly, of photoreceptor cells) slightly decreased. Increased GFAP immunoreactivity revealed a hypertrophy and reactivity of the Müller cells in 1-year-old taiep rats. CONCLUSIONS The present results suggest the occurrence of a relatively mild and slowly progressing neural retinal alteration in taiep rats, which becomes histologically and functionally evident at the end of the first year of life, and mainly affects the circuit(s) of the photopic ON-response. It is speculated that this alteration is due to missing/altered signals from demyelinated optic nerve.
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Affiliation(s)
- Andrés E Chávez
- Molecular Cellular Center for Neuroscience of Valparaiso, Faculty of Science, University of Valparaíso, P.O. Box 5030, Valparaíso, Chile
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Palma F, Roncagliolo P, Bacigalupo J, Palacios AG. Membrane current of retinal rods of Caudiverbera caudiverbera (Amphibia: Leptodactylidae): dark noise, spectral and absolute light sensitivity. Vis Neurosci 2001; 18:663-73. [PMID: 11829312 DOI: 10.1017/s0952523801184166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We investigated the photocurrents from isolated rods of the South American anuran, Caudiverbera caudiverbera. Rod outer segments were on average 66.4 +/- 11.2 microm (mean +/- S.D., n = 104) in length and 6.6 +/- 0.9 microm (mean +/- S.D.) in diameter: 40 +/- 22 photoisomerizations (mean +/- S.D., range 10-99, n = 16) were required for eliciting a half-saturating photocurrent response. The time-to-peak was 911 +/- 217 ms (mean +/- S.D., n = 14, 20 degrees C) in the linear range of the response and the integration time of the current response was 1744 +/- 451 ms (mean +/- S.D., n = 14). The time-to-peak appears to be slower and the integration time shorter in Caudiverbera than in Ambystoma tigrinum, Rana pipiens or Xenopus laevis rods under similar experimental conditions. The a-band of rod spectral sensitivity has a lambda(max) at 520 +/- 2.1 nm (mean +/- S.D., range 516-525 nm, n = 24) and the bandwidth fits a porphyropsin visual pigment. The single-event response amplitude ranges from 0.31-0.51 pA, depending on the calculation method. The intrinsic dark current (variance at dark minus variance under bright light) was 0.045 +/- 0.040 pA2 (mean +/- S.D., n = 24). Our results support the presence of a dark-noise component below 1 Hz, with kinetics similar to the single-photon evoked response and a rate of 0.006 events s(-1) (n = 9).
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Affiliation(s)
- F Palma
- Department of Physiology, Faculty of Sciences, and Valparaíso Molecular and Cellular Center for Neuroscience, University of Valparaíso, Chile
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27
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Abstract
The spectral sensitivities of retinal cones isolated from goldfish (Carassius auratus) retinas were measured in the range 277-737 nm by recording membrane photocurrents with suction pipette electrodes (SPE). Cones were identified with lambda max (+/- S.D.) at 623 +/- 6.9 nm, 537 +/- 4.7 nm, 447 +/- 7.7 nm, and about 356 nm (three cells). Two cells (lambda max 572 and 576 nm) possibly represent genetic polymorphism. A single A2 template fits the alpha-band of P447(2), P537(2), and P623(2). HPLC analysis showed 4% retinal:96% 3-dehydroretinal. Sensitivity at 280 nm is nearly half that at the lambda max in the visible. The lambda max of the beta-band (in nm) is a linear function of the lambda max of the alpha-band and follows the same relation as found for A1-based cone pigments of a cyprinid fish.
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Affiliation(s)
- A G Palacios
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA
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Abstract
Photocurrents from isolated rods of adults and sub-adults of three species of amphibians, Rana pipiens, Ambystoma tigrinum, and Xenopus laevis, were measured with suction pipette electrodes. The intensity for a half-maximal response was 0.91+/-0.48 photons microm(-2) flash(-1) (mean +/- S.D., 10-ms flashes) for Rana, 0.92+/-0.44 for Ambystoma, and 6.14+/-1.33 for Xenopus. The mean number of photoisomerizations at half-saturation was 22+/-12 for Rana, 50+/-24 for Ambystoma, and 221+/-48 for Xenopus. The photocurrent per photoisomerization is several times smaller in Xenopus rods than in the other two species. Spectral sensitivity was measured from 277-737 nm with light polarized both parallel and perpendicular to the planes of the membrane disks. Dichroism fell in the near UV and was absent in the region of absorption by tryptophan and tyrosine. Maximum sensitivity of Rana was at 503.9+/-2.6 nm (n = 86), and of Ambystoma, 505.8+/-1.8 nm (n = 24). Animals from these same batches that were sampled by HPLC had no 3-dehydroretinal (retinal2). Xenopus containing about 94% retinal2 and 6% retinal1 had lambda(max) at 519.3+/-2.7 nm (n = 11). Spectral position of the beta-band, estimated by the method of Stavenga et al. (1993), appears to be at longer wavelengths in amphibian photoreceptors than in other vertebrates. Fits of log sensitivity to a normalized-frequency template that tracks the long-wavelength tail of the alpha-band (Lamb, 1995) show that the rod pigments of Rana and Ambystoma are slightly narrower than those found in the photoreceptors of fish and mammals.
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Affiliation(s)
- A G Palacios
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA
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van Roessel P, Palacios AG, Goldsmith TH. Activity of long-wavelength cones under scotopic conditions in the cyprinid fish Danio aequipinnatus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1997; 181:493-500. [PMID: 9373956 DOI: 10.1007/s003590050133] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In carp (Cyprinus) and goldfish (Carassius), long-wavelength cones are reported to be active under scotopic conditions. Using the electroretinogram (ERG), we tested another cyprinid fish, Danio aequipinnatus, which contains A1-based visual pigments and for which we had previously measured the spectral sensitivities of individual cones. Dark adaptation curves show a rod/cone break at about 45 min. When thoroughly dark-adapted, the spectral sensitivity function is broader than can be accounted for by self-screening of rhodopsin, but it can be modeled by an additive combination of rods and the 560-nm cones. Dim, red background light causes adaptation of rods and a broadening of the spectral sensitivity function, which can be simulated by increasing the proportion of cones in the model. Brighter red backgrounds adapt the 560-nm cones. Because of the effect of red adapting lights, the ERG evidence for the participation of long-wavelength cones close to visual threshold appears to be different in Danio than in the goldfish Carassius.
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Affiliation(s)
- P van Roessel
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven 06520-8103, USA
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Abstract
Photocurrents of cones in the retinas of a small fish, Danio aequipinnatus (Cyprinidae) were recorded with suction pipette electrodes. Spectral sensitivity was measured between 277 and 697 nm. Four spectral classes of cone were found, with lambdamax at 560, 480, 408, and 358 nm. For the latter, we provide the first complete characterization of spectral sensitivity of a vertebrate ultraviolet (UV) photoreceptor. All cones responded with similar kinetics, except for a subset of the 560-nm cones, which were distinctly faster. The alpha-bands of the three cones absorbing maximally in the visible have the same bandwidth when log sensitivity is plotted versus normalized frequency, and in this respect they are indistinguishable from primate cones ("Mansfield's rule"). An eighth-degree polynomial in lambdamax/lambda based on this combined data set (fish, primate) is presented as a template that is likely to have predictive value in describing cone spectra from other vertebrates. The alpha-band of the UV cone, however, is somewhat narrower than predicted by this function, is similar to other UV visual pigments, and an eighth-degree polynomial that describes its shape is also presented. These measurements also provide information on the beta-band (i.e. cis peak region), difficult to obtain by microspectrophotometry. The beta-band of cone pigments is found at longer wavelengths as the alpha-band shifts toward the red. A secondary rise in cone sensitivity around 280 nm indicates that photons absorbed by aromatic amino acids in the opsin (gamma-band) excite the transduction cascade, but the quantum efficiency is not as high as when absorption occurs in the retinal-protein chromophore.
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Affiliation(s)
- A G Palacios
- Department of Biology, Yale University, New Haven, CT 06520-8103, USA
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Palacios AG, Goldsmith TH. Visual transduction in vertebrate rods. Biol Res 1996; 29:313-7. [PMID: 9278702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- A G Palacios
- Department of Biology, Yale University, New Haven, CT 06520-8103, USA.
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Abstract
1. Membrane photocurrents were recorded from outer segments of isolated retinal rods of pigeons (Columba livia), the first such measurements on the photoreceptors of a bird. The amplitude of the response to 20 ms flashes of narrow wavelength bands of light increases linearly with intensity at low photon fluxes and saturates at higher intensities. The maximum (saturating) photocurrent observed in forty-nine rod cells was 50 pA. Larger responses with less variability in the intensity for half-maximal responses were observed when the physiological saline contained 20 mM bicarbonate (in addition to Hepes buffer). 2. The dependence of peak amplitude on intensity is well fitted by an exponential function; it is usually less well fitted by the Michaelis-Menten (Naka-Rushton) equation. 3. In the presence of bicarbonate, the average sensitivity of pigeon rods to dim flashes was 0.56 pA photon-1 microns -2. The effective collecting area per photon was 1.8 microns 2. About 83 +/- 26 (mean +/- S.D.) photoisomerizations were required for a half-saturating response. 4. The response kinetics of rods to dim flashes can be reasonably well described by a series of four to five either Poisson or independent filters. The time to peak, measured from the mid-point of a 20 ms flash, was 319 +/- 83 ms (mean +/- S.D.). The integration time of the response was 851 +/- 86 ms (mean +/- S.D.) with bicarbonate present and 572 +/- 126 ms in the absence of bicarbonate. The responses of pigeon rods appear to be slower than those of mammals at the same temperature. The fraction of current suppressed by a single photoisomerization is smaller in pigeon than in mammalian rods by a factor of at least two. 5. The spectral sensitivity function was measured between 680 and 330 nm. The maximum at about 505 nm (range 497-508 nm) corresponds to the alpha-band of a vertebrate rhodopsin and agrees with previous behavioural measurements of scotopic sensitivity of pigeons as well as the absorption spectrum of extracts of pigeon rhodopsin. There was no pronounced beta-band in the near-ultraviolet wavelengths.
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Affiliation(s)
- A G Palacios
- Department of Biology, Yale University, New Haven, CT 06511
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Palacios AG, Varela FJ. Color mixing in the pigeon (Columba livia) II: A psychophysical determination in the middle, short and near-UV wavelength range. Vision Res 1992; 32:1947-53. [PMID: 1287991 DOI: 10.1016/0042-6989(92)90054-m] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Pigeons were trained to discriminate between spectral lights and additive mixtures in the 350-560 nm spectral range using a successive "autoshaping" discrimination procedure [introduced in Palacios, Martinoya, Bloch & Varela, Vision Research, 30, 587-596 (1990)]. Dichromatic mixtures were found in the short and near UV region, but not in the middle-wave region. Our results suggest that color vision in the pigeon involves the active participation of five different primary mechanisms, which are differentially active in the yellow- and red-sensitive retinal fields.
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Affiliation(s)
- A G Palacios
- Institut des Neurosciences, Université de Paris 6-CNRS, France
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