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Strettoi E, Di Marco B, Orsini N, Napoli D. Retinal Plasticity. Int J Mol Sci 2022; 23:ijms23031138. [PMID: 35163059 PMCID: PMC8835074 DOI: 10.3390/ijms23031138] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 01/17/2022] [Accepted: 01/18/2022] [Indexed: 12/28/2022] Open
Abstract
Brain plasticity is a well-established concept designating the ability of central nervous system (CNS) neurons to rearrange as a result of learning, when adapting to changeable environmental conditions or else while reacting to injurious factors. As a part of the CNS, the retina has been repeatedly probed for its possible ability to respond plastically to a variably altered environment or to pathological insults. However, numerous studies support the conclusion that the retina, outside the developmental stage, is endowed with only limited plasticity, exhibiting, instead, a remarkable ability to maintain a stable architectural and functional organization. Reviewed here are representative examples of hippocampal and cortical paradigms of plasticity and of retinal structural rearrangements found in organization and circuitry following altered developmental conditions or occurrence of genetic diseases leading to neuronal degeneration. The variable rate of plastic changes found in mammalian retinal neurons in different circumstances is discussed, focusing on structural plasticity. The likely adaptive value of maintaining a low level of plasticity in an organ subserving a sensory modality that is dominant for the human species and that requires elevated fidelity is discussed.
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Affiliation(s)
- Enrica Strettoi
- CNR Neuroscience Institute, 56124 Pisa, Italy; (B.D.M.); (N.O.); (D.N.)
- Correspondence: ; Tel.: +39-0503153213
| | - Beatrice Di Marco
- CNR Neuroscience Institute, 56124 Pisa, Italy; (B.D.M.); (N.O.); (D.N.)
- Regional Doctorate School in Neuroscience, Universities of Florence, Pisa and Siena, 50134 Florence, Italy
| | - Noemi Orsini
- CNR Neuroscience Institute, 56124 Pisa, Italy; (B.D.M.); (N.O.); (D.N.)
- Regional Doctorate School in Neuroscience, Universities of Florence, Pisa and Siena, 50134 Florence, Italy
| | - Debora Napoli
- CNR Neuroscience Institute, 56124 Pisa, Italy; (B.D.M.); (N.O.); (D.N.)
- Regional Doctorate School in Neuroscience, Universities of Florence, Pisa and Siena, 50134 Florence, Italy
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Makowiecki K, Garrett A, Clark V, Graham SL, Rodger J. Reliability of VEP Recordings Using Chronically Implanted Screw Electrodes in Mice. Transl Vis Sci Technol 2015; 4:15. [PMID: 25938003 DOI: 10.1167/tvst.4.2.15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 03/09/2015] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Visual evoked potentials (VEPs) are widely used to objectively assess visual system function in animal models of ophthalmological diseases. Although use of chronically implanted electrodes is common in longitudinal VEP studies using rodent models, reliability of recordings over time has not been assessed. We compared VEPs 1 and 7 days after electrode implantation in the adult mouse. We also examined stimulus-independent changes over time, by assessing electroencephalogram (EEG) power and approximate entropy of the EEG signal. METHODS Stainless steel screws (600-μm diameter) were implanted into the skull overlying the right visual cortex and the orbitofrontal cortex of adult mice (C57Bl/6J, n = 7). Animals were reanesthetized 1 and 7 days after implantation to record VEP responses (flashed gratings) and EEG activity. Brain sections were stained for glial activation (GFAP) and cell death (TUNEL). RESULTS Reliability analysis, using intraclass correlation coefficients, showed VEP recordings had high reliability within the same session, regardless of time after electrode implantation and peak latencies and approximate entropy of the EEG did not change significantly with time. However, there was poorer reliability between recordings obtained on different days, and a significant decrease in VEP amplitudes and EEG power. This amplitude decrease could be normalized by scaling to EEG power (within-subjects). Furthermore, glial activation was present at both time points but there was no evidence of cell death. CONCLUSIONS These results indicate that VEP responses can be reliably recorded even after a relatively short recovery period but decrease response peak amplitude over time. Although scaling the VEP trace to EEG power normalized this decrease, our results highlight that time-dependent cortical excitability changes are an important consideration in longitudinal VEP studies. TRANSLATIONAL RELEVANCE This study shows changes in VEP characteristics over time in chronically implanted mice. Thus, future preclinical longitudinal studies should consider time in addition to amplitude and latency when designing and interpreting research.
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Affiliation(s)
- Kalina Makowiecki
- Experimental and Regenerative Neurosciences School of Animal Biology, The University of Western Australia, Crawley WA, Australia
| | - Andrew Garrett
- Experimental and Regenerative Neurosciences School of Animal Biology, The University of Western Australia, Crawley WA, Australia
| | - Vince Clark
- Experimental and Regenerative Neurosciences School of Animal Biology, The University of Western Australia, Crawley WA, Australia
| | - Stuart L Graham
- Australian School Advanced Medicine Macquarie University, New South Wales, Australia
| | - Jennifer Rodger
- Experimental and Regenerative Neurosciences School of Animal Biology, The University of Western Australia, Crawley WA, Australia
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Abstract
The hormonal control of cell death is currently the best-established mechanism for creating sex differences in cell number in the brain and spinal cord. For example, males have more cells than do females in the principal nucleus of the bed nucleus of the stria terminalis (BNSTp) and spinal nucleus of the bulbocavernosus (SNB), whereas females have a cell number advantage in the anteroventral periventricular nucleus (AVPV). In each case, the difference in cell number in adulthood correlates with a sex difference in the number of dying cells at some point in development. Mice with over- or under-expression of cell death genes have been used to test more directly the contribution of cell death to neural sex differences, to identify molecular mechanisms involved, and to determine the behavioural consequences of suppressing developmental cell death. Bax is a pro-death gene of the Bcl-2 family that is singularly important for apoptosis in neural development. In mice lacking bax, the number of cells in the BNSTp, SNB and AVPV are significantly increased, and sex differences in total cell number in each of these regions are eliminated. Cells rescued by bax gene deletion in the BNSTp express markers of differentiated neurones and the androgen receptor. On the other hand, sex differences in other phenotypically identified populations, such as vasopressin-expressing neurones in the BNSTp or dopaminergic neurones in AVPV, are not affected by either bax deletion or bcl-2 over-expression. Possible mechanisms by which testosterone may regulate cell death in the nervous system are discussed, as are the behavioural effects of eliminating sex differences in neuronal cell number.
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Affiliation(s)
- N G Forger
- Department of Psychology and Center for Neuroendocrine Studies, University of Massachusetts, Amherst, MA 01003, USA.
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Jyotika J, McCutcheon J, Laroche J, Blaustein JD, Forger NG. Deletion of the Bax gene disrupts sexual behavior and modestly impairs motor function in mice. Dev Neurobiol 2007; 67:1511-9. [PMID: 17525992 DOI: 10.1002/dneu.20525] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cell death is a nearly ubiquitous feature of the developing nervous system, and differential death in males and females contributes to several well studied sex differences in neuron number. Nonetheless, the functional importance of neuronal cell death has been subjected to few direct tests. Bax, a pro-apoptotic protein, is required for cell death in many neural regions. Deletion of the Bax gene in mice increases neuron number in several areas and eliminates sex differences in cell number in the brain and spinal cord. Here, sexual and motor behaviors were examined in Bax-/- mice and their wild-type siblings to test the functional consequences of preventing Bax-dependent cell death. Animals were gonadectomized in adulthood and provided with ovarian hormones or with testosterone for tests of feminine and masculine sexual behaviors, respectively. Wild-type mice exhibited a sex difference in feminine sexual behavior, with high lordosis scores in females and low scores in males. This sex difference was eliminated by Bax deletion, with very low receptivity exhibited by both male and female Bax-/- mice. Masculine sexual behavior was not sexually dimorphic among wild-type mice, but mounts and pelvic thrusts were nearly eliminated in Bax-/- mice of both sexes. Motor strength and performance at low speeds on a RotaRod apparatus did not differ by sex or Bax gene status. However, Bax-/- animals exhibited impairments on the RotaRod at higher speeds. Thus, developmental cell death may be required for masculine and feminine sexual behaviors and the fine tuning of motor coordination.
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Affiliation(s)
- Jigyasa Jyotika
- Department of Psychology and Neuroscience and Behavior Program, University of Massachusetts, Amherst, Massachusetts 01003, USA
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Abstract
Mouse models of optic nerve disease such as glaucoma, optic neuritis, ischemic optic neuropathy, and mitochondrial optic neuropathy are being developed at increasing rate to investigate specific pathophysiological mechanisms and the effect of neuroprotective treatments. The use of these models may be greatly enhanced by the availability of non-invasive methods able to monitor retinal ganglion cell (RGC) function longitudinally such as the Pattern Electroretinogram (PERG). While the use of the PERG as a tool to probe inner retina function in mammals is known since 25 years, relatively less information is available for the mouse. Here, the PERG technique and the main applications in the mouse are reviewed.
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Affiliation(s)
- Vittorio Porciatti
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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Frenkel MY, Sawtell NB, Diogo ACM, Yoon B, Neve RL, Bear MF. Instructive Effect of Visual Experience in Mouse Visual Cortex. Neuron 2006; 51:339-49. [PMID: 16880128 DOI: 10.1016/j.neuron.2006.06.026] [Citation(s) in RCA: 216] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Revised: 06/16/2006] [Accepted: 06/27/2006] [Indexed: 11/24/2022]
Abstract
We describe a form of experience-dependent response enhancement in the visual cortex of awake mice. Repeated presentations of grating stimuli of a single orientation result in a persistent enhancement of responses evoked by the test stimulus. Response potentiation is specific to the orientation of the test stimulus, develops gradually over the course of several training sessions, and occurs in both juvenile and adult mice. The stimulus-selective response potentiation (SRP) can mask deprivation-induced response depression in adult mice. SRP requires NMDA receptor activation and is prevented by viral delivery of a peptide that interferes with AMPA receptor trafficking. SRP may reveal the mechanisms involved in certain forms of perceptual learning.
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Affiliation(s)
- Mikhail Y Frenkel
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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Abstract
The programmed cell death (PCD) of developing cells is considered an essential adaptive process that evolved to serve diverse roles. We review the putative adaptive functions of PCD in the animal kingdom with a major focus on PCD in the developing nervous system. Considerable evidence is consistent with the role of PCD in events ranging from neurulation and synaptogenesis to the elimination of adult-generated CNS cells. The remarkable recent progress in our understanding of the genetic regulation of PCD has made it possible to perturb (inhibit) PCD and determine the possible repercussions for nervous system development and function. Although still in their infancy, these studies have so far revealed few striking behavioral or functional phenotypes.
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Affiliation(s)
- Robert R Buss
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
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Ben-Shlomo G, Ofri R. Development of inner retinal function, evidenced by the pattern electroretinogram, in the rat. Exp Eye Res 2006; 83:417-23. [PMID: 16626702 DOI: 10.1016/j.exer.2006.01.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 01/09/2006] [Accepted: 01/11/2006] [Indexed: 10/24/2022]
Abstract
Though the rat is increasingly used as an animal model in ophthalmic research, including the study of glaucoma, little is known about age-related changes in its inner retinal function. The aim of this study was to evaluate these changes in the rat during the first 18 weeks of life. The pattern electroretinogram (PERG) was used to monitor inner retinal activity in 16 developing rats. In each animal, recordings were conducted at ages 3, 5, 7, 11, 14 and 18 weeks to assess age-related changes in function. Signals were evoked by five stimuli of progressively increasing check width (subtending 82-1312 arc minutes of visual angle) that were projected directly onto the fundus through a specially modified ophthalmoscope which allowed visual and manual control of stimulus quality. Poor signal:noise ratio prevented signal analysis at age 3 weeks. Subsequently, PERG amplitude increased significantly, up to 242% (depending on stimulus check width), during weeks 5-11. After peaking at 11 weeks, signal amplitude declined moderately. Signal latency mirrored that of amplitude, decreasing during the first 11 weeks, and then increasing steadily. Latency was not affected by stimulus check width. Age was highly correlated with P1 latency (R(2)=0.80) and moderately correlated with N2 latency (R(2)=0.52). Therefore, we propose that studies of inner retinal diseases (such as glaucoma) in the rat model should use age-matched controls, as electrophysiological results may be confounded by age-related changes. The rat PERG undergoes many of the age-related changes that have been reported in humans, and thus may serve as an animal model to study development of inner retinal function.
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Affiliation(s)
- Gil Ben-Shlomo
- Koret School of Veterinary Medicine, Hebrew University of Jerusalem, PO Box 12, Herzl Street, Rehovot 76100, Israel
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Ben-Shlomo G, Bakalash S, Lambrou GN, Latour E, Dawson WW, Schwartz M, Ofri R. Pattern electroretinography in a rat model of ocular hypertension: functional evidence for early detection of inner retinal damage. Exp Eye Res 2005; 81:340-9. [PMID: 16129101 DOI: 10.1016/j.exer.2005.02.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2004] [Revised: 01/16/2005] [Accepted: 02/16/2005] [Indexed: 10/25/2022]
Abstract
With the increasing use of the rat as an animal model for glaucoma and for the evaluation of neuroprotective treatments, there is a need for a sensitive test of retinal ganglion cell (RGC) function in this species. The aims of this study were to detect functional abnormalities of the inner retina in a rat model of high intraocular pressure (IOP) using the pattern electroretinogram (PERG), and to correlate them with morphometric analysis of RGC survival and the functional integrity of the inner retina. Unilateral ocular hypertension was induced in 17 Lewis rats through laser photocoagulation. Pattern ERGs were recorded prior to lasering and 3 weeks later, using a series of shifting patterns of decreasing spatial frequency projected directly onto the animals' fundus. IOP was measured at the same intervals, and the number of surviving RGCs estimated. Low amplitude PERG signals could be recorded in response to a narrow grating of 0.368 cycles per degree (cpd), and increased with stimulus size. Lasering caused mean (+/-s.d.) IOP to increase significantly from 18.3+/-4.5 (baseline) to 29.8+/-8.8 mmHg within 3 weeks (p<0.0001). At this time, PERG amplitudes were significantly reduced (p<0.05), declining an average of 45% compared to the normotensive, control eyes. No outer retinal damage was observed, but the mean number of RGCs decreased significantly (p<0.001), from 2 525.0+/-372.4 to 1 542.8+/-333.8 cells per mm2. This decrease in RGC number was significantly (p=0.03) correlated the decrease in PERG amplitude. The correlation between functional integrity of the inner retina and the rat PERG was further demonstrated by intravitreal tetrodotoxin injections, which temporarily abolished the PERG but did not affect outer retinal activity, reflected in the flash ERG. The evidence for early functional deficits, combined with tonometry and documentation of correlated ganglion cells loss, confirms the sensitivity of this diagnostic tool and the validity and importance of this animal model in glaucoma research.
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Affiliation(s)
- Gil Ben-Shlomo
- Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Herzl Street, P.O. Box 12, Rehovot 76100, Israel
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Ridder WH, Nusinowitz S. The visual evoked potential in the mouse--origins and response characteristics. Vision Res 2005; 46:902-13. [PMID: 16242750 DOI: 10.1016/j.visres.2005.09.006] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Revised: 09/05/2005] [Accepted: 09/07/2005] [Indexed: 11/15/2022]
Abstract
The visual evoked potential (VEP) in the mouse is characterized and compared to responses obtained with the electroretinogram (ERG). The results indicate that: 1, the VEP originates in the visual cortex; 2, the rod and cone pathways contribute separately to the VEP; 3, temporal tuning functions for rod and cone ERGs are low pass and band pass, respectively; VEP tuning functions are both band pass; and 4, VEP acuity is 0.62+/-0.156 cycles/degree. The differences in the spatial and temporal tuning functions obtained from the retina and visual cortex provides a tool to investigate signal processing through the visual system.
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Affiliation(s)
- W H Ridder
- Southern California College of Optometry, Fullerton, CA, USA
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Abstract
The consequences of eliminating the process of programmed cell death during the development of the nervous system is examined by reviewing studies in the genetic model organisms Caenorhabditis elegans, Drosophila melanogaster, Danio rerio and Mus musculus, where mutations of cell death genes have eliminated or reduced programmed cell death in the nervous system. In many cases, genetic elimination of cell death leads to embryonic mortality or gross anatomical malformations; however, there are cases where animals develop normally but with excess neurons and glia in the nervous system. Undead cells either differentiate and function as working neurons, in some instances being of smaller size, or fail to differentiate and lack normal connections with their targets. Changes in motor control and sensory processing are generally not observed, except for during the most complex of behaviors. Examination of organisms where death genes have been genetically eliminated reveals that programmed cell death may play an important role in sculpting gross brain structure during early development of the neural tube. In contrast, the consequences of preventing neuronal cell death at later developmental stages (e.g. during vertebrate synapse formation) are just beginning to be understood.
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Affiliation(s)
- Robert R Buss
- Department of Neurobiology and Anatomy and the Neuroscience Program, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1010, USA
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Rondi-Reig L, Mariani J. To die or not to die, does it change the function? Behavior of transgenic mice reveals a role for developmental cell death. Brain Res Bull 2002; 57:85-91. [PMID: 11827740 DOI: 10.1016/s0361-9230(01)00639-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In humans, perturbations in the developmental neuronal death leading to an excess of neurons could be associated with developmental neuropsychiatric disorders. Hu-bcl-2 transgenic mice appear to be a valuable tool to study the functional role of developmental programmed cell death. Indeed, the over-expression of the anti-apoptotic gene bcl-2 decreases developmental neuronal death and Hu-bcl-2 mice present supernumerary neurons in several brain regions. A detailed behavioral analysis of these mice revealed selective deficits. Hu-bcl-2 mice have normal vision, general activity and motor skills. Only the most complex behavior like anxiety and learning abilities are impaired in these mice.
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Affiliation(s)
- Laure Rondi-Reig
- Neurobiologie des Processus Adaptatifs, Lab. Développement et Vieillissement du Sysème Nerveux (DVSN), Université P&M Curie, Paris, France.
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Porciatti V, Pizzorusso T, Maffei L. Electrophysiology of the postreceptoral visual pathway in mice. Doc Ophthalmol 2002; 104:69-82. [PMID: 11949810 DOI: 10.1023/a:1014463212001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Pattern VEPs have been recorded locally from the binocular portion of the primary visual cortex of wild type- and different transgenic mice by means of microelectrodes. Local pattern VEPs have been used on the one hand to obtain information on basic cortical layout (topography, laminar analysis) and ocularity (relative contribution of the contralateral and ipsilateral eye), and on the other hand to evaluate several aspects of visual physiology that have a counterpart in visual behavior (visual acuity, contrast sensitivity, motion sensitivity, response latency). As compared to visual behavior, pattern VEPs offer the advantage that several aspects of vision can be evaluated in the same animals, including those with poor behavior due to motor- or cognitive deficits, even during the postnatal development. Pattern VEPs provide a means for characterizing the visual phenotype of mutant mice and for the evaluation of the effects induced by experimental manipulation.
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Rondi-Reig L, Lemaigre-Dubreuil Y, Montécot C, Müller D, Martinou JC, Caston J, Mariani J. Transgenic mice with neuronal overexpression of bcl-2 gene present navigation disabilities in a water task. Neuroscience 2001; 104:207-15. [PMID: 11311543 DOI: 10.1016/s0306-4522(01)00050-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In the CNS, Bcl-2 is an antiapoptotic gene involved in the regulation of neuronal death. Transgenic mice overexpressing the human gene Bcl-2 (Hu-bcl-2 mice) showed delayed acquisition in two tasks requiring them to find a hidden platform starting from either a random or a constant starting location. The same mice were not deficient in another task requiring them to find a visible platform suggesting that the delay observed was not due to motor, visual or motivational deficits in the water. The delay observed in Hu-bcl-2 mice was more important in the random starting test in which the allocentric demand for navigation was stronger. The results suggested that allocentric navigation is particularly sensitive to abnormal CNS maturation following the overexpression of the bcl-2 gene. The specific deficits (motor learning, fear-related behavior and allocentric navigation) observed in Hu-bcl-2 mice suggest that the regulation of developmental neuronal death is crucial for multisensorial learning and emotional behavior.
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Affiliation(s)
- L Rondi-Reig
- Laboratoire Développement et Vieillissement du Système Nerveux, Institut des Neurosciences, CNRS UMR 7624, Université P&M Curie, 9 quai Saint-Bernard, 75005, Paris, France.
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