We studied changes in the expression of growth‐associated protein 43 (GAP43), glial fibrillary acidic protein (GFAP), and calcium‐binding proteins (calbindin Cb and parvalbumin Pv) in the dorsal ...lateral geniculate nucleus (dLGN) of four capuchin monkeys with laser‐induced retinal lesions. The lesions were generated with the aid of a neodymium‐YAG dual‐frequency laser with shots of different intensity and at different survival time in each animal. The expression of these proteins in the layers of the dLGN was evaluated by performing histodensitometry of coronal sections throughout the nucleus. High‐power laser shots administered at the border of the optic disc (OD)‐injured fibers resulted in large scotomas. These lesions produced a devastating effect on fibers in this passage, resulting in large deafferentation of the dLGN. The time course of plasticity expressed in this nucleus varied with the degree of the retinal lesion. Topographically, corresponding portions of the dLGN were inferred by the extent of the ocular dominance column revealed by cytochrome oxidase histochemistry in flattened preparations of V1. In the region representing the retinal lesion, the expression of GFAP, GAP43, Pv, and Cb increased and decreased in the corresponding dLGN layers shortly after lesion induction and returned to their original values with different time courses. Synaptogenesis (indicated by GAP43 expression) appeared to be increased in all layers, while “cleansing” of the glial‐damaged region (indicated by GFAP expression) was markedly greater in the parvocellular layers, followed by the magnocellular layers.
Schematic drawings of optic discs laser lesions and of series of coronal sections of the dLGN, in three monkeys, depicting the areas of the nucleus deafferented by the lesions.
Schematic drawings of optic discs laser lesions and of series of coronal sections of the dLGN, in three monkeys, depicting the areas of the nucleus deafferented by the lesions.
We quantified the capacity for reorganization of the topographic representation of area V1 in adult monkeys. Bias-free automated mapping methods were used to delineate receptive fields (RFs) of an ...array of neuronal clusters prior to, and up to 6 h following retinal lesions. Monocular lesions caused a significant reorganization of the topographic map in this area, both inside and outside the cortical lesion projection zone (LPZ). Small flashed stimuli revealed responses up to 0.85 mm inside the boundaries of the LPZ, with RFs representing regions of undamaged retina immediately surrounding the lesion. In contrast, long moving bars that spanned the scotoma resulting from the lesion revealed responsive units up to 1.87 mm inside the LPZ, with RFs representing interpolated responses in this region. This reorganization is present immediately after monocular retinal lesioning. Both stimuli showed a similar and significant (5-fold) increase of the RF scatter in the LPZ, 0.56 mm (median), compared with the undamaged retina, 0.12 mm. Our results reveal an array of preexisting subthreshold functional connections of up to 2 mm in V1, which can be rapidly mobilized independently from the differential qualitative reorganization elicited by each stimulus.
This study aims to identify the temporal variation and the spatial dependence structure of the hospitalization rate for falls in the elderly residing in Brazil in the period between 2010 and 2021. ...This ecological study employs secondary data from the Brazilian Ministry of Health about the fall-related hospitalization of people aged 60 years old and over. A time-series analysis was carried out, employing the joinpoint model. For the spatial analysis, the Moran autocorrelation technique was employed. In Brazil, between 2010 and 2021, there were 1,270,341 hospitalizations for falls recorded among the elderly in the Brazilian Hospitalization System. There was a continuous upward trend between 2010 and 2019 for all age groups, female and male, and all Brazilian regions. The trend stabilized between 2019 to 2021. The North and Northeast regions had faster upward trends among all Brazilian regions, and there was also a faster upward trend among women compared to men. A high-high pattern in hospitalization incidence was noticed from 2011 to 2019 in the states of São Paulo, Minhas Gerais, Paraná, and Mato Grosso do Sul. The results of this study provide subsidies for Brazilian health authorities to implement more efficient public policies to improve the quality of life of elderly people.
Huntington's disease (HD) is a late-onset, slowly progressing neurodegenerative disorder caused by an expansion of glutamine repeats. The YAC128 mouse model has been widely used to study the ...progression of HD symptoms, but little is known about synaptic alterations in very old animals. The present experiments examined synaptic properties of striatal medium-sized spiny neurons (MSNs) in 16 month-old YAC128 mice. These mice were crossed with mice expressing enhanced green fluorescent protein (EGFP) under the control of either D1 or D2 dopamine receptor promoters to identify MSNs originating the direct and indirect pathways, respectively. The input-output curves of evoked excitatory postsynaptic currents mediated by activation of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) or N-methyl-D-aspartate (NMDA) receptors were reduced in MSNs in both pathways. In the presence of DL-threo-β-Benzyloxyaspartic acid (DL-TBOA), a glutamate transporter blocker used to increase activation of extrasynaptic receptors, NMDA receptor-mediated currents displayed altered amplitudes, longer decay times, and greater charge (response areas) in both direct and indirect pathway MSNs in YAC128 mice compared to wildtype controls. Amplitudes were significantly increased, primarily in direct pathway MSNs while normalized areas were significantly increased only in indirect pathway MSNs, suggesting that the two types of MSNs are affected in different ways. It may be that indirect pathway neurons are more susceptible to changes in glutamate transport. Taken together, the present findings demonstrate differential alterations in synaptic versus extrasynaptic NMDA receptors in both direct and indirect pathway MSNs in late HD, which may contribute to the dysfunction and degeneration in both pathways.
We studied the distribution of the calcium-binding proteins calbindin, parvalbumin and calretinin, in the superior colliculus and in the lateral geniculate nucleus of
Cebus apella, a diurnal New ...World monkey. In the superior colliculus, these calcium-binding proteins show different distribution patterns throughout the layers. After reaction for calretinin one observes a heavy staining of the neuropil with few labeled cells in superficial layers, a greater number of large and medium-sized cells in the stratum griseum intermediale, and small neurons in deep layers. The reaction for calbindin revealed a strong staining of neuropil with a large number of small and well stained cells, mainly in the upper half of the stratum griseum superficiale. Intermediate layers were more weakly stained and depicted few neurons. There were few immunopositive cells and little neuropil staining in deep layers. The reaction for parvalbumin showed small and medium-sized neurons in the superficial layers, a predominance of large stellate cells in the stratum griseum intermediale, and medium-sized cells in the deep layers. In the lateral geniculate nucleus of
Cebus, parvalbumin is found in the cells of both the P and M pathways, whereas calbindin is mainly found in the interlaminar and S layers, which are part of the third visual pathway. Calretinin was only found in cells located in layer S. This pattern is similar to that observed in
Macaca, showing that these calcium-binding proteins reveal different components of the parallel visual pathways both in New and Old World monkeys.
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