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Mikhalkin AA, Nikitina NI, Merkulyeva NS. Early postnatal development of the primary visual areas 17 and 18 of the cat cerebral cortex: An SMI-32 study. J Neurosci Res 2024; 102:e25375. [PMID: 39105520 DOI: 10.1002/jnr.25375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 06/04/2024] [Accepted: 07/26/2024] [Indexed: 08/07/2024]
Abstract
Using anti-neurofilament H non-phosphorylated antibodies (SMI-32) as markers for the neuronal maturation level and Y channel responsible for motion processing, we investigated early postnatal development of the primary visual areas 17 and 18 in cats aged 0, 10, 14, and 34 days and in adults. Two analyzed parameters of SMI-32-immunolabeling were used: the total proportion of SMI-32-labeling and the density of labeled neurons. (i) The developmental time course of the total proportion of SMI-32-labeling shows the general increase in the accumulation of heavy-chain neurofilaments. This parameter showed a different time course for cortical layer development; the maximal increment in the total labeling in layer V occurred between the second and fifth postnatal weeks and in layers II-III and VI after the fifth postnatal week. In addition, the delay in accumulation of SMI-32-labeling was shown in layer V of the area 17 periphery representation during the first two postnatal weeks. (ii) The density of SMI-32-labeled neurons decreased in all layers of area 18, but was increased, decreased, or had a transient peak in layers II-III, V, and VI of area 17, respectively. The transient peak is in good correspondence with some transient neurochemical features previously revealed for different classes of cortical and thalamic neurons and reflects the time course of the early development of the thalamocortical circuitry. Some similarities between the time courses for the development of SMI-32-labeling in areas 17/18 and in A- and C-laminae of the LGNd allow us to propose heterochronous postnatal development of two Y sub-channels.
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Affiliation(s)
- A A Mikhalkin
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
| | - N I Nikitina
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
| | - N S Merkulyeva
- Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia
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2
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Merkulyeva N, Mikhalkin A, Veshchitskii A. Inner Structure of the Lateral Geniculate Complex of Adult and Newborn Acomys cahirinus. Int J Mol Sci 2024; 25:7855. [PMID: 39063096 PMCID: PMC11277159 DOI: 10.3390/ijms25147855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2024] [Revised: 07/14/2024] [Accepted: 07/15/2024] [Indexed: 07/28/2024] Open
Abstract
Acomys cahirinus is a unique Rodentia species with several distinctive physiological traits, such as precocial development and remarkable regenerative abilities. These characteristics render A. cahirinus increasingly valuable for regenerative and developmental physiology studies. Despite this, the structure and postnatal development of the central nervous system in A. cahirinus have been inadequately explored, with only sporadic data available. This study is the first in a series of papers addressing these gaps. Our first objective was to characterize the structure of the main visual thalamic region, the lateral geniculate complex, using several neuronal markers (including Ca2+-binding proteins, glutamic acid decarboxylase enzyme, and non-phosphorylated domains of heavy-chain neurofilaments) to label populations of principal neurons and interneurons in adult and newborn A. cahirinus. As typically found in other rodents, we identified three subdivisions in the geniculate complex: the dorsal and ventral lateral geniculate nuclei (LGNd and LGNv) and the intergeniculate leaflet (IGL). Additionally, we characterized internal diversity in the LGN nuclei. The "shell" and "core" regions of the LGNd were identified using calretinin in adults and newborns. In adults, the inner and outer parts of the LGNv were identified using calbindin, calretinin, parvalbumin, GAD67, and SMI-32, whereas in newborns, calretinin and SMI-32 were employed for this purpose. Our findings revealed more pronounced developmental changes in LGNd compared to LGNv and IGL, suggesting that LGNd is less mature at birth and more influenced by visual experience.
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Affiliation(s)
- Natalia Merkulyeva
- Neuromorphology Laboratory, Pavlov Institute of Physiology of Russian Academy of Sciences, St. Petersburg 199034, Russia; (A.M.); (A.V.)
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Merkulyeva N, Mikhalkin A. Transient expression of heavy-chain neurofilaments in the perigeniculate nucleus of cats. Brain Struct Funct 2024; 229:489-495. [PMID: 38265459 DOI: 10.1007/s00429-023-02752-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Accepted: 12/12/2023] [Indexed: 01/25/2024]
Abstract
The perigeniculate nucleus (PGN) is a visual part of the thalamic reticular nucleus modulating the information transfer between the lateral geniculate nucleus and the visual cortex. This study focused on the postnatal development of the PGN in cats, using the SMI-32 antibody, which recognizes non-phosphorylated heavy-chain neurofilaments responsible for neuronal structural maturation and is also used as a marker for motion processing, or Y, stream. We questioned whether transient neuronal populations exist in the PGN and can they possibly be related to the Y processing stream. We uncovered a transient, robust SMI-32 staining in the PGN of kittens aged 0-34 days with the significant decline in the cellular density of labeled cells in older animals. According to the double-labeling, in all examined age groups, perigeniculate SMI-32-immunopositive cells are part of the main parvalbumin-positive population. The maximal cellular density of the double-stained cells appeared in animals aged 10-28 days. We also revealed that the most significant growth of perigeniculate cells's soma occurred at three postnatal weeks. The possible link of our data to the development of the Y visual processing stream and to the heterogeneity of the perigeniculate neuronal population is also discussed.
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Affiliation(s)
- Natalia Merkulyeva
- Pavlov Institute of Physiology RAS, Makarov Nab., 6, Saint-Petersburg, Russia, 199034.
| | - Aleksandr Mikhalkin
- Pavlov Institute of Physiology RAS, Makarov Nab., 6, Saint-Petersburg, Russia, 199034
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Henneberry JM, Elgallad J, Smith S, Duffy KR. Early monocular deprivation reduces the capacity for neural plasticity in the cat visual system. Cereb Cortex Commun 2023; 4:tgad017. [PMID: 37675436 PMCID: PMC10477708 DOI: 10.1093/texcom/tgad017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 07/26/2023] [Accepted: 07/30/2023] [Indexed: 09/08/2023] Open
Abstract
Obstruction of vision to one eye during early postnatal development elicits neural modifications in the visual system that can last a lifetime. Research in rodents has revealed that an early and transient monocular deprivation (MD) can produce an enduring alteration to the framework of neural connections within visual cortex. This lasting trace of early MD enables an enhanced effect of a second MD imposed on the same eye in adulthood. In the current study, we examined whether the modification of plasticity potential was bidirectional by assessing whether the effect of early and brief MD attenuated the impact of a subsequent MD when applied to the fellow eye. Results were clear in showing that animals with an early MD exhibited a smaller response to later visual deprivation of the fellow eye. Compared to controls, animals with a history of MD exhibited less atrophy of neurons, and a smaller loss of neurofilament labeling within the dorsal lateral geniculate nucleus. The shift in cortical ocular dominance elicited by MD was also smaller in animals with a prior MD. These results indicate that early MD elicits abiding and eye-specific neural modifications that can selectively alter plasticity potential in the visual system.
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Affiliation(s)
- Jonathon Mark Henneberry
- Department of Psychology and Neuroscience, Dalhousie University, 1355 Oxford St., Halifax, NS B3H 4R2, Canada
| | - Joseph Elgallad
- Department of Psychology and Neuroscience, Dalhousie University, 1355 Oxford St., Halifax, NS B3H 4R2, Canada
| | - Seth Smith
- Department of Psychology and Neuroscience, Dalhousie University, 1355 Oxford St., Halifax, NS B3H 4R2, Canada
| | - Kevin R Duffy
- Department of Psychology and Neuroscience, Dalhousie University, 1355 Oxford St., Halifax, NS B3H 4R2, Canada
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Duffy KR, Crowder NA, Heynen AJ, Bear MF. Comparative analysis of structural modifications induced by monocular retinal inactivation and monocular deprivation in the developing cat lateral geniculate nucleus. J Comp Neurol 2023; 531:1244-1260. [PMID: 37139534 PMCID: PMC10330129 DOI: 10.1002/cne.25493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 04/10/2023] [Accepted: 04/13/2023] [Indexed: 05/05/2023]
Abstract
During a critical period of postnatal life, monocular deprivation (MD) by eyelid closure reduces the size of neurons in layers of the dorsal lateral geniculate nucleus (dLGN) connected to the deprived eye and shifts cortical ocular dominance in favor of the non-deprived eye. Temporary inactivation of the non-deprived eye can promote superior recovery from the effects of long-term MD compared to conventional occlusion therapy. In the current study, we assessed the modification of neuron size in the dLGN as a means of measuring the impact of a brief period of monocular inactivation (MI) imposed at different postnatal ages. The biggest impact of MI was observed when it occurred at the peak of the critical period. Unlike the effect of MD, structural plasticity following MI was observed in both the binocular and monocular segments of the dLGN. With increasing age, the capacity for inactivation to alter postsynaptic cell size diminished but was still significant beyond the critical period. In comparison to MD, inactivation produced effects that were about double in magnitude and exhibited efficacy at older ages. Notwithstanding the large neural alterations precipitated by MI, its effects were remediated with a short period of binocular experience, and vision through the previously inactivated eye fully recovered. These results demonstrate that MI is a potent means of modifying the visual pathway and does so at ages when occlusion is ineffective. The efficacy and longevity of inactivation to elicit plasticity highlight its potential to ameliorate disorders of the visual system such as amblyopia.
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Affiliation(s)
- Kevin R Duffy
- Department of Psychology & Neuroscience, Dalhousie University, Halifax, Canada
| | - Nathan A Crowder
- Department of Psychology & Neuroscience, Dalhousie University, Halifax, Canada
| | - Arnold J Heynen
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Mark F Bear
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Mikhalkin AA, Nikitina NI, Merkulyeva NS. Age-Related Changes in Soma Size of Y Neurons in the Cat Dorsal Lateral Geniculate Nucleus: Dorsoventral and Centroperipheral Gradients. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022060126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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7
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Mikhalkin AA, Merkulyeva NS. Peculiarities of Age-Related Dynamics of Neurons in the Cat Lateral Geniculate Nucleus as Revealed in Frontal versus Sagittal Slices. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021050021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Aronitz EM, Kamermans BA, Duffy KR. Development of parvalbumin neurons and perineuronal nets in the visual cortex of normal and dark-exposed cats. J Comp Neurol 2021; 529:2827-2841. [PMID: 33576496 DOI: 10.1002/cne.25127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 02/07/2021] [Accepted: 02/08/2021] [Indexed: 11/06/2022]
Abstract
During development, the visual system maintains a high capacity for modification by expressing characteristics permissive for plasticity, enabling neural circuits to be refined by visual experience to achieve their mature form. This period is followed by the emergence of characteristics that stabilize the brain to consolidate for lifetime connections that were informed by experience. Attenuation of plasticity potential is thought to derive from an accumulation of plasticity-inhibiting characteristics that appear at ages beyond the peak of plasticity. Perineuronal nets (PNNs) are molecular aggregations that primarily surround fast-spiking inhibitory neurons called parvalbumin (PV) cells, which exhibit properties congruent with a plasticity inhibitor. In this study, we examined the development of PNNs and PV cells in the primary visual cortex of a highly visual mammal, and assessed the impact that 10 days of darkness had on both characteristics. Here, we show that labeling for PV expression emerges earlier and reaches adult levels sooner than PNNs. We also demonstrate that darkness, a condition known to enhance plasticity, significantly reduces the density of PNNs and the size of PV cell somata but does not alter the number of PV cells in the visual cortex. The darkness-induced reduction of PV cell size occurred irrespective of whether neurons were surrounded by a PNN, suggesting that PNNs have a restricted capacity to inhibit plasticity. Finally, we show that PV cells surrounded by a PNN were significantly larger than those without one, supporting the view that PNNs may mediate trophic support to the cells they surround.
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Affiliation(s)
- Elise M Aronitz
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Braden A Kamermans
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Kevin R Duffy
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
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Mikhalkin A, Nikitina N, Merkulyeva N. Heterochrony of postnatal accumulation of nonphosphorylated heavy‐chain neurofilament by neurons of the cat dorsal lateral geniculate nucleus. J Comp Neurol 2020; 529:1430-1441. [DOI: 10.1002/cne.25028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 08/24/2020] [Accepted: 09/02/2020] [Indexed: 12/18/2022]
Affiliation(s)
- Aleksandr Mikhalkin
- lab Neuromorphology Pavlov Institute of Physiology RAS Makarov emb, 6 Saint‐Petersburg Russia
| | - Nina Nikitina
- lab Neuromorphology Pavlov Institute of Physiology RAS Makarov emb, 6 Saint‐Petersburg Russia
| | - Natalia Merkulyeva
- lab Neuromorphology Pavlov Institute of Physiology RAS Makarov emb, 6 Saint‐Petersburg Russia
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10
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Modification of Peak Plasticity Induced by Brief Dark Exposure. Neural Plast 2019; 2019:3198285. [PMID: 31565047 PMCID: PMC6745115 DOI: 10.1155/2019/3198285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 05/13/2019] [Accepted: 05/22/2019] [Indexed: 11/29/2022] Open
Abstract
The capacity for neural plasticity in the mammalian central visual system adheres to a temporal profile in which plasticity peaks early in postnatal development and then declines to reach enduring negligible levels. Early studies to delineate the critical period in cats employed a fixed duration of monocular deprivation to measure the extent of ocular dominance changes induced at different ages. The largest deprivation effects were observed at about 4 weeks postnatal, with a steady decline in plasticity thereafter so that by about 16 weeks only small changes were measured. The capacity for plasticity is regulated by a changing landscape of molecules in the visual system across the lifespan. Studies in rodents and cats have demonstrated that the critical period can be altered by environmental or pharmacological manipulations that enhance plasticity at ages when it would normally be low. Immersion in complete darkness for long durations (dark rearing) has long been known to alter plasticity capacity by modifying plasticity-related molecules and slowing progress of the critical period. In this study, we investigated the possibility that brief darkness (dark exposure) imposed just prior to the critical period peak can enhance the level of plasticity beyond that observed naturally. We examined the level of plasticity by measuring two sensitive markers of monocular deprivation, namely, soma size of neurons and neurofilament labeling within the dorsal lateral geniculate nucleus. Significantly larger modification of soma size, but not neurofilament labeling, was observed at the critical period peak when dark exposure preceded monocular deprivation. This indicated that the natural plasticity ceiling is modifiable and also that brief darkness does not simply slow progress of the critical period. As an antecedent to traditional amblyopia treatment, darkness may increase treatment efficacy even at ages when plasticity is at its highest.
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11
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Abstract
It has been shown that the visual acuity loss experienced by the deprived eye of kittens following an early period of monocular deprivation (MD) can be alleviated rapidly following 10 days of complete darkness when imposed even as late as 14 weeks of age. To examine whether 10 days of darkness conferred benefits at any age, we measured the extent of recovery of the visual acuity of the deprived eye following the darkness imposed on adult cats that had received the same early period of MD as used in prior experiments conducted on kittens. Parallel studies conducted on different animals examined the extent to which darkness changed the magnitude of the MD-induced laminar differences of the cell soma size and immunoreactivity for the neurofilament (NF) protein in the dorsal lateral geniculate nucleus (dLGN). The results indicated that 10 days of darkness imposed at one year of age neither alleviated the acuity loss of the deprived eye induced by an earlier period of MD nor did it decrease the concurrent lamina differences of the soma size or NF loss in the dLGN.
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Duffy KR, Fong MF, Mitchell DE, Bear MF. Recovery from the anatomical effects of long-term monocular deprivation in cat lateral geniculate nucleus. J Comp Neurol 2017; 526:310-323. [PMID: 29023717 DOI: 10.1002/cne.24336] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 10/05/2017] [Accepted: 10/06/2017] [Indexed: 11/06/2022]
Abstract
Monocular deprivation (MD) imposed early in postnatal life elicits profound structural and functional abnormalities throughout the primary visual pathway. The ability of MD to modify neurons within the visual system is restricted to a so-called critical period that, for cats, peaks at about one postnatal month and declines thereafter so that by about 3 months of age MD has little effect. Recovery from the consequences of MD likewise adheres to a critical period that ends by about 3 months of age, after which the effects of deprivation are thought to be permanent and without capacity for reversal. The attenuation of plasticity beyond early development is a formidable obstacle for conventional therapies to stimulate recovery from protracted visual deprivation. In the current study we examined the efficacy of dark exposure and retinal inactivation with tetrodotoxin to promote anatomical recovery in the dorsal lateral geniculate nuclues (dLGN) from long-term MD started at the peak of the critical period. Whereas 10 days of dark exposure or binocular retinal inactivation were not better at promoting recovery than conventional treatment with reverse occlusion, inactivation of only the non-deprived (fellow) eye for 10 days produced a complete restoration of neuron soma size, and also reversed the significant loss of neurofilament protein within originally deprived dLGN layers. These results reveal a capacity for neural plasticity and recovery that is larger than anything previously observed following protracted MD in cat, and they highlight a possibility for alternative therapies applied at ages thought to be recalcitrant to recovery.
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Affiliation(s)
- Kevin R Duffy
- Department of Psychology & Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Ming-Fai Fong
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Donald E Mitchell
- Department of Psychology & Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Mark F Bear
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
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Duffy KR, Lingley AJ, Holman KD, Mitchell DE. Susceptibility to monocular deprivation following immersion in darkness either late into or beyond the critical period. J Comp Neurol 2016; 524:2643-53. [PMID: 26878686 DOI: 10.1002/cne.23985] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 02/06/2016] [Accepted: 02/08/2016] [Indexed: 01/04/2023]
Abstract
An extended duration of darkness starting near the time of birth preserves immature neuronal characteristics and prolongs the accentuated plasticity observed in young animals. Brief periods of complete darkness have emerged as an effective means of restoring a high capacity for neural plasticity and of promoting recovery from the effects of monocular deprivation (MD). We examined whether 10 days of darkness imposed in adulthood or beyond the peak of the critical period could rejuvenate the ability of MD to reduce the size of neuron somata within deprived layers of the cat dorsal lateral geniculate nucleus (dLGN). For adult cats subjected to 10 days of darkness before 7 days of MD, we observed no alteration in neuron size or neurofilament labeling within the dLGN. At 12 weeks of age, MD that followed immediately after 10 days of darkness produced an enhanced reduction of neuron soma size within deprived dLGN layers. For this age we observed that 10 days of darkness also enhanced the loss of neurofilament protein within deprived dLGN layers. These results indicate that, although 10 days of darkness in adulthood does not enhance the susceptibility to 7 days of MD, darkness imposed near the trailing edge of the critical period can restore a heightened susceptibility to MD more typical of an earlier developmental stage. The loss of neurofilament in juveniles exposed to darkness prior to MD suggests that the enhanced capacity for structural plasticity is partially rooted in the ability of darkness to modulate molecules that inhibit plasticity. J. Comp. Neurol. 524:2643-2653, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Kevin R Duffy
- Department of Psychology and Neuroscience, Dalhousie University Life Sciences Centre, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Alexander J Lingley
- Department of Psychology and Neuroscience, Dalhousie University Life Sciences Centre, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Kaitlyn D Holman
- Department of Psychology and Neuroscience, Dalhousie University Life Sciences Centre, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Donald E Mitchell
- Department of Psychology and Neuroscience, Dalhousie University Life Sciences Centre, Halifax, Nova Scotia, Canada, B3H 4R2
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Mitchell DE, MacNeill K, Crowder NA, Holman K, Duffy KR. Recovery of visual functions in amblyopic animals following brief exposure to total darkness. J Physiol 2015; 594:149-67. [PMID: 26449521 DOI: 10.1113/jp270981] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 09/20/2015] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS Occlusion of one eye of kittens (monocular deprivation) results in a severe and permanent loss of visual acuity in that eye, which parallels closely the vision loss characteristic of human amblyopia. We extended earlier work to demonstrate that amblyopic vision loss can be either blocked or erased very fast by a 10 day period of total darkness following a period of monocular deprivation that begins near birth and extends to at least 8 weeks of age. The parameters of darkness were strict because no visual recovery was observed after 5 days of darkness. In addition, short periods of light introduced each day during an otherwise 10 day period of darkness obliterated the benefits. Despite recovery of normal visual acuity, only one-quarter of the animals showed evidence of having attained normal stereoscopic vision. A period of total darkness may catalyse and improve treatment outcomes in amblyopic children. A 10 day period of total darkness has been shown to either block or erase the severe effects on vision of a prior short period of monocular deprivation (MD) in kittens depending on whether darkness is contiguous or is delayed with respect to the period of MD. We have extended these earlier findings from kittens for which the period of MD began at 1 month and lasted for 1 week to more clinically relevant situations where MD began near birth and lasted for ≥ 6 weeks. Despite the far longer MD and the absence of prior binocular vision, all animals recovered normal visual acuity in the previously deprived eye. As before, when the period of darkness followed immediately after MD, the vision of both eyes was initially very poor but, subsequently, the acuity of each eye increased gradually and equally to attain normal levels in ∼ 7 weeks. By contrast, when darkness was introduced 8 weeks after MD, the visual acuity of the deprived eye recovered quickly to normal levels in just 1 week without any change in the vision of the fellow (non-deprived) eye. Short (15 or 30 min) periods of illumination each day during an otherwise 10 day period of darkness obliterated all the benefits for vision, and a 5 day period of darkness was also completely ineffective. Measurements of depth perception indicated that, despite possessing normal visual acuity in both eyes, only about one-quarter of the animals showed evidence of having attained normal stereoscopic vision.
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Affiliation(s)
- Donald E Mitchell
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Katelyn MacNeill
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Orthoptics, IWK Hospital, Halifax, Nova Scotia, Canada.,Hospital for Sick Children, Toronto, Ontario, Canada
| | - Nathan A Crowder
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Kaitlyn Holman
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Kevin R Duffy
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
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Song S, Mitchell DE, Crowder NA, Duffy KR. Postnatal accumulation of intermediate filaments in the cat and human primary visual cortex. J Comp Neurol 2015; 523:2111-26. [PMID: 25823892 DOI: 10.1002/cne.23781] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 03/16/2015] [Accepted: 03/17/2015] [Indexed: 12/25/2022]
Abstract
A principal characteristic of the mammalian visual system is its high capacity for plasticity in early postnatal development during a time commonly referred to as the critical period. The progressive diminution of plasticity with age is linked to the emergence of a collection of molecules called molecular brakes that reduce plasticity and stabilize neural circuits modified by earlier visual experiences. Manipulation of braking molecules either pharmacologically or though experiential alteration enhances plasticity and promotes recovery from visual impairment. The stability of neural circuitry is increased by intermediate filamentous proteins of the cytoskeleton such as neurofilaments and α-internexin. We examined levels of these intermediate filaments within cat and human primary visual cortex (V1) across development to determine whether they accumulate following a time course consistent with a molecular brake. In both species, levels of intermediate filaments increased considerably throughout early postnatal life beginning shortly after the peak of the critical period, with the highest levels measured in adults. Neurofilament phosphorylation was also observed to increase throughout development, raising the possibility that posttranslational modification by phosphorylation reduces plasticity due to increased protein stability. Finally, an approach to scale developmental time points between species is presented that compares the developmental profiles of intermediate filaments between cats and humans. Although causality between intermediate filaments and plasticity was not directly tested in this study, their accumulation relative to the critical period indicates that they may contribute to the decline in plasticity with age, and may also constrain the success of treatments for visual disorders applied in adulthood.
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Affiliation(s)
- Seoho Song
- Department of Psychology and Neuroscience, Dalhousie University, Life Sciences Centre, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Donald E Mitchell
- Department of Psychology and Neuroscience, Dalhousie University, Life Sciences Centre, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Nathan A Crowder
- Department of Psychology and Neuroscience, Dalhousie University, Life Sciences Centre, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Kevin R Duffy
- Department of Psychology and Neuroscience, Dalhousie University, Life Sciences Centre, Halifax, Nova Scotia, Canada, B3H 4R2
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Duffy KR, Bukhamseen DH, Smithen MJ, Mitchell DE. Binocular eyelid closure promotes anatomical but not behavioral recovery from monocular deprivation. Vision Res 2014; 114:151-60. [PMID: 25536470 DOI: 10.1016/j.visres.2014.12.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 12/12/2014] [Accepted: 12/14/2014] [Indexed: 10/24/2022]
Abstract
Deprivation of patterned vision of frontal eyed mammals early in postnatal life alters structural and functional attributes of neurones in the central visual pathways, and can produce severe impairments of the vision of the deprived eye that resemble the visual loss observed in human amblyopia. A traditional approach to treatment of amblyopia has been the occlusion of the stronger fellow eye in order to force use of the weaker eye and thereby strengthen its connections in the visual cortex. Although this monocular treatment strategy can be effective at promoting recovery of visual acuity of the amblyopic eye, such binocular visual functions as stereoscopic vision often remain impaired due in part to the lack of concordant vision during the period of unilateral occlusion. The recent development of binocular approaches for treatment of amblyopia that improve the possibility for binocular interaction have achieved success in promoting visual recovery. The full and rapid recovery of visual acuity observed in amblyopic kittens placed in complete darkness is an example of a binocular treatment whose success may in part derive from a restored balance of visually-driven neural activity. In the current study we examined as an alternative to dark rearing the efficacy of binocular lid suture (BLS) to stimulate anatomical and visual recovery from a preceding amblyogenic period of monocular deprivation. In the dorsal lateral geniculate nucleus (dLGN) of monocularly deprived kittens, darkness or BLS for 10days produced a complete recovery of neurone soma size within initially deprived layers. The growth of neurone somata within initially deprived dLGN layers after darkness or BLS was accompanied by an increase in neurotrophin-4/5 labeling within these layers. Although anatomical recovery was observed in both recovery conditions, BLS failed to promote any improvement of the visual acuity of the deprived eye no matter whether it followed immediately or was delayed with respect to the prior period of monocular deprivation. Notwithstanding the lack of visual recovery with BLS, all animals in the BLS condition that were subsequently placed in darkness exhibited a substantial recovery of visual acuity in the amblyopic eye. We conclude that the balanced binocular visual input provided by BLS does not stimulate the collection of neural events necessary to support recovery from amblyopia. The complete absence of visually-driven activity that occurs with dark rearing evidently plays an important role in the recovery process.
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Affiliation(s)
- Kevin R Duffy
- Department of Psychology and Neuroscience, Dalhousie University, Life Sciences Centre, Halifax, NS B3H 4R2, Canada.
| | - Dalia H Bukhamseen
- Department of Psychology and Neuroscience, Dalhousie University, Life Sciences Centre, Halifax, NS B3H 4R2, Canada
| | - Matthew J Smithen
- Department of Psychology and Neuroscience, Dalhousie University, Life Sciences Centre, Halifax, NS B3H 4R2, Canada
| | - Donald E Mitchell
- Department of Psychology and Neuroscience, Dalhousie University, Life Sciences Centre, Halifax, NS B3H 4R2, Canada
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Shrinkage of X cells in the lateral geniculate nucleus after monocular deprivation revealed by FoxP2 labeling. Vis Neurosci 2014; 31:253-61. [PMID: 24480423 DOI: 10.1017/s0952523813000643] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The parallel processing of visual features by distinct neuron populations is a central characteristic of the mammalian visual system. In the A laminae of the cat dorsal lateral geniculate nucleus (dLGN), parallel processing streams originate from two principal neuron types, called X and Y cells. Disruption of visual experience early in life by monocular deprivation has been shown to alter the structure and function of Y cells, but the extent to which deprivation influences X cells remains less clear. A transcription factor, FoxP2, has recently been shown to selectively label X cells in the ferret dLGN and thus provides an opportunity to examine whether monocular deprivation alters the soma size of X cells. In this study, FoxP2 labeling was examined in the dLGN of normal and monocularly deprived cats. The characteristics of neurons labeled for FoxP2 were consistent with FoxP2 being a marker for X cells in the cat dLGN. Monocular deprivation for either a short (7 days) or long (7 weeks) duration did not alter the density of FoxP2-positive neurons between nondeprived and deprived dLGN layers. However, for each deprived animal examined, measurement of the cross-sectional area of FoxP2-positive neurons (X cells) revealed that within deprived layers, X cells were smaller by approximately 20% after 7 days of deprivation, and by approximately 28% after 7 weeks of deprivation. The observed alteration to the cross-sectional area of X cells indicates that perturbation of this major pathway contributes to the functional impairments that develop from monocular deprivation.
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18
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Mitchell DE, Kennie J, Duffy KR. Preference for binocular concordant visual input in early postnatal development remains despite prior monocular deprivation. Vision Res 2011; 51:1351-9. [DOI: 10.1016/j.visres.2011.04.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 04/07/2011] [Accepted: 04/14/2011] [Indexed: 10/18/2022]
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Monocular deprivation provokes alteration of the neuronal cytoskeleton in developing cat lateral geniculate nucleus. Vis Neurosci 2009; 26:319-28. [PMID: 19519963 DOI: 10.1017/s0952523809090130] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Monocular deprivation early in development produces considerable change in the organization of connections within the central mammalian visual system. In the dorsal lateral geniculate nucleus, the soma, dendrites, and axon terminal fields of deprived cells become considerably smaller than nondeprived counterparts. We have examined the possibility that subcellular events enabling structural modification of deprived neurons include modification of proteins comprising the cytoskeleton. We examined the integrity of the cytoskeleton by measuring the response of a subset of its proteins to varying durations of monocular deprivation. Loss of all three neurofilament subunits (light, medium, and heavy) within deprived layers was observed to parallel changes in neuron gross structure. Monocular deprivation initiated beyond early life produced neither a change in structure nor a loss of neurofilament labeling.
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