Layer specific regulation of critical period timing and maturation of mouse visual cortex by endocannabinoids.

Plasticity during the critical period is important for the functional maturation of cortical neurons. While characteristics of plasticity are diverse among cortical layers, it is unknown whether critical period timing is controlled by a common or unique molecular mechanism among them. We here clarified layer-specific regulation of the critical period timing of ocular dominance plasticity in the primary visual cortex.

Dark Rearing Promotes the Recovery of Visual Cortical Responses but Not the Morphology of Geniculocortical Axons in Amblyopic Cat.

Monocular deprivation (MD) of vision during early postnatal life induces amblyopia, and most neurons in the primary visual cortex lose their responses to the closed eye. Anatomically, the somata of neurons in the closed-eye recipient layer of the lateral geniculate nucleus (LGN) shrink and their axons projecting to the visual cortex retract. Although it has been difficult to restore visual acuity after maturation, recent studies in rodents and cats showed that a period of exposure to complete darkness could promote recovery from amblyopia induced by prior MD.

The Influence of Illumination Color on the Subjective Visual Recognition of Biological Specimens.

Background: Visual examination by the naked eye is integral to medical diagnosis and surgery. The illumination in conditioned color is widely used for visual inspection in the industry but has not been introduced to the biomedical context. The color that can enhance the visual recognition of individual tissues is still unknown.

Latent TGF-β binding protein-2 is essential for the development of ciliary zonule microfibrils.

Latent TGF-β-binding protein-2 (LTBP-2) is an extracellular matrix protein associated with microfibrils. Homozygous mutations in LTBP2 have been found in humans with genetic eye diseases such as congenital glaucoma and microspherophakia, indicating a critical role of the protein in eye development, although the function of LTBP-2 in vivo has not been well understood. In this study, we explore the in vivo function of LTBP-2 by generating Ltbp2(-/-) mice.

Developmental and visual input-dependent regulation of the CB1 cannabinoid receptor in the mouse visual cortex.

The mammalian visual system exhibits significant experience-induced plasticity in the early postnatal period. While physiological studies have revealed the contribution of the CB1 cannabinoid receptor (CB1) to developmental plasticity in the primary visual cortex (V1), it remains unknown whether the expression and localization of CB1 is regulated during development or by visual experience. To explore a possible role of the endocannabinoid system in visual cortical plasticity, we examined the expression of CB1 in the visual cortex of mice.

Difference in binocularity and ocular dominance plasticity between GABAergic and excitatory cortical neurons.

Neuronal circuits in the cerebral cortex consist mainly of glutamatergic/excitatory and GABAergic/inhibitory neurons. In the visual cortex, the binocular responsiveness of neurons is modified by monocular visual deprivation during the critical period of postnatal development. Although GABAergic neurons are considered to play a key role in the expression of the critical period, it is not known whether their binocular responsiveness and ocular dominance plasticity are different from those of excitatory neurons.

GABAergic neurons are less selective to stimulus orientation than excitatory neurons in layer II/III of visual cortex, as revealed by in vivo functional Ca2+ imaging in transgenic mice.

Most neurons in the visual cortex are selectively responsive to visual stimulation of a narrow range of orientations, and GABAergic neurons are considered to play a role in the formation of such orientation selectivity. This suggests that response properties of GABAergic neurons may be different from those of excitatory neurons. This view remains unproved, however.

Recovery of binocular responses after brief monocular deprivation in kittens.

Monocular deprivation induces a rapid ocular dominance change in the developing visual cortex. The early phase of the change is supposed to be labile and stabilized later by consolidation processes. To test the stability of early ocular dominance change, we examined whether binocular responses of cortical neurons can recover after a brief monocular deprivation in anesthetized and paralyzed kittens in which ocular dominance plasticity does not operate.

Chronic electrical stimulation of afferents from one eye changes ocular dominance of visual cortical neurons in kittens.

Binocular visual responsiveness of neurons in visual cortex of the cat can be changed by monocular visual deprivation in the critical period of postnatal development. It is hypothesized that afferents from each eye compete with one another for synaptic connections with cortical neurons so that less active afferents from the deprived eye fail to maintain the connections. This hypothesis predicts that an increase in inputs from one eye instead of decrease due to deprivation should also change binocular responsiveness of cortical neurons.