Short periods of darkness fail to restore visual or neural plasticity in adult cats

2018 ◽  
Vol 35 ◽  
Author(s):  
KAITLYN D. HOLMAN ◽  
KEVIN R. DUFFY ◽  
DONALD E. MITCHELL
Keyword(s):  
Visual Acuity ◽  
Neural Plasticity ◽  
Early Period ◽  
Monocular Deprivation ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Soma Size ◽  
Visual Acuity Loss ◽  
Adult Cats ◽  
One Year ◽  
Dorsal Lateral Geniculate

AbstractIt 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.

scholarly journals Modification of Peak Plasticity Induced by Brief Dark Exposure

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Alexander J. Lingley ◽  
Donald E. Mitchell ◽  
Nathan A. Crowder ◽  
Kevin R. Duffy
Keyword(s):  
Visual System ◽  
Neural Plasticity ◽  
Critical Period ◽  
Ocular Dominance ◽  
Monocular Deprivation ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Soma Size ◽  
Slow Progress ◽  
Dark Exposure ◽  
Central Visual System

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.

Selective expression and rapid regulation of GABAA receptor subunits in geniculocortical neurons of macaque dorsal lateral geniculate nucleus

1996 ◽  
Vol 13 (2) ◽  
pp. 223-235 ◽  
Author(s):  
Stewart H. C. Hendry ◽  
Karen L. Miller
Keyword(s):  
Lateral Geniculate Nucleus ◽  
Monocular Deprivation ◽  
Functional Adaptation ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Double Labeling ◽  
Visual Activity ◽  
Inhibitory Neurotransmission ◽  
Lateral Geniculate ◽  
Inhibitory Mechanisms ◽  
Dorsal Lateral Geniculate

AbstractMonocular deprivation in adult macaques produces a rapid down-regulation in GABA and GABAA receptor subunit immunoreactivity in deprived-eye columns of primary visual cortex (V1) but a significantly delayed GABA reduction in deprived layers of the dorsal lateral geniculate nucleus (LGN). These findings, suggesting that normal inhibitory neurotransmission persists in LGN at a time when V1 inhibitory mechanisms are greatly altered, are consistent with physiological studies that have demonstrated a greater degree of functional plasticity in V1 than in LGN. Nonetheless, functional adaptation to partial loss of visual input has been detected in the LGN, indicating that synaptic plasticity takes place in this nucleus. In the present study, evidence for early changes in inhibitory neurotransmission were examined with immunocytochemical methods to determine if, in the absence of early GABA regulation, GABAA receptor subunits in macaque LGN are affected by adult deprivation. Immunoreactivity for α1 and β2/3 subunits of the GABAA receptor was intense within the magnocellular layers and more modest in the parvocellular layers and intercalated layers. In all layers, immunoreactivity was present in the cytoplasm and along the surfaces of relatively large somata and in dense tangles of processes in the neuropil. Double-labeling experiments demonstrated that somata and processes immunoreactive for α 1 and β2/3 were surrounded by GABA terminals but no cell intensely immunoreactive for either subunit expressed immunoreactivity for GABA, itself. Following periods of monocular deprivation by tetrodotoxin (TTX) injection for 4 days or longer, layers deprived of visual activity displayed levels of α 1 and β2/3 immunoreactivity markedly lower than those displayed by the adjacent, normally active layers. Such changes were greater as the period of deprivation increased. The changes included a loss of immunostaining in and around somata and in many neuropil elements of deprived layers. These data indicate that GABA and GABAA receptor subunits α 1 and β2/3 are expressed by separate populations of neurons in macaque LGN that are differentially regulated by visual activity. The findings suggest that rapid, activity-dependent regulation of postsynaptic receptors represents one mechanism for altering synaptic strength in the adult macaque visual system.

Degree of interocular synchrony required for maintenance of binocularity in kitten's visual cortex

1979 ◽  
Vol 42 (6) ◽  
pp. 1692-1710 ◽  
Author(s):  
G. G. Blasdel ◽  
J. D. Pettigrew
Keyword(s):  
Visual Cortex ◽  
Substantial Reduction ◽  
Monocular Deprivation ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Cortical Cells ◽  
The Third ◽  
Monocular Stimulation ◽  
Cortical Inputs ◽  
Dorsal Lateral Geniculate ◽  
Stimulation Of

1. The importance of synchronous activation in maintaining cortical binocularity was studied physiologically in kittens that had been reared under different regimens of alternating monocular deprivation. 2. Three different techniques were employed to provide alternate monocular stimulation: a) mechanical shutters placed before the animals' eyes; b) goggles fitted with complementary colored cutoff filters, which restricted visual input to one eye at a time; and c) two rotating gratings that were 90 degrees out of phase. In the third technique, the gratings were always orthogonal to one another and viewed separately through cutoff filters. This allowed us to exploit the orientation selectivity of cortical cells and thereby stimulate them alternately through each eye without simultaneously affecting activity in the dorsal lateral geniculate nucleus (dLGN). 3. We based our conclusions on a sample of 691 neurons, which we recorded in 21 animals. Results with all techniques were remarkably consistent. Binocular cortical inputs predominated at normal or nearly normal levels, even when a number of seconds elapsed between successive exposures of each eye. 4. An interonset interval of at least 10 s was required to make a substantial reduction in binocularity. This interval can be separated into two parts--the duration of exclusive monocular stimulation and the time when neither channel receives input. Of these, the latter appeared to be less important. Blanking times of 0.15--1.0 s did not affect binocularity if the interonset interval was 1 or 10 s; and in one experiment where the blanking time was 9 s, the resulting disruption in binocularity was less than that found with shorter blanking times and the same interonset interval. 5. Our results imply that mechanisms responsible for the disappearance of binocular cortical inputs require independent stimulation of each eye for periods of at least a few seconds; this stimulation must be of a kind that is known to excite cortical cells. Our results with the rotating grafting show, in addition, that the mechanisms whose timing we have measured are intrinsic to the cortex.

scholarly journals One-year post-operative comparison of visual function and patient satisfaction with trifocal and extended depth of focus intraocular lenses

2021 ◽  
pp. 112067212110697
Author(s):  
Elizabeth M. Law ◽  
Rajesh K. Aggarwal ◽  
Hetal Buckhurst ◽  
Hosam E. Kasaby ◽  
Jonathan Marsden ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Contrast Sensitivity ◽  
Early Period ◽  
Intraocular Lenses ◽  
Depth Of Focus ◽  
Extended Depth Of Focus ◽  
Quality Of Vision ◽  
Significant Difference ◽  
One Year

Purpose To evaluate visual performance with trifocal and extended depth of focus IOL at 1 year post-operatively. Setting BMI Southend Hospital. Design Cohort study. Methods An age-matched cohort of forty subjects bilaterally implanted with the AT LISA 839MP trifocal IOL (20 patients, 40 eyes) and the Tecnis Symfony extended depth of focus IOL (20 patients, 40 eyes) were assessed at 3–6 months and 12–18 months post-operatively. Primary outcome measures were distance (6 m), intermediate (70 cm), near visual acuity (40 cm), and analysis of defocus profiles. Secondary outcomes included contrast sensitivity, Radner reading performance, quality of vision and assessment of halos. Results Distance visual acuity (VA) and defocus areas were similar ( p = 0.07). No significant difference in intermediate VA was noted but the intermediate area of focus was greater in the EDoF (0.31 ± 0.12 LogMAR*m−1) compared to the trifocal (0.22 ± 0.08LogMAR*m−1) ( p = 0.02). However, all near metrics were significantly better in the trifocal group. 80% of trifocal subjects were spectacle independent compared to 50% EDoF subjects. Quality of vision questionnaire found no significant differences between groups, however halo scores were greater at 3–6 months in the trifocal group ( p < 0.01) but no differences were noted at 12–18 months. Conclusions Near vision is significantly better for the trifocal, thus greater levels of spectacle independence. The range of intermediate vision was greater for the EDoF but no difference in intermediate VA. In the early period, differences in contrast sensitivity and halo size/intensity were noted, however, by one-year these measures were not significantly different.

Sign in / Sign up

Export Citation Format

Share Document