Reorganization of cortical representations after focal visual cortex lesions has been documented. It has been suggested that functional reorganization may rely on cellular mechanisms involving modifications in the excitatory/inhibitory neurotransmission balance and on morphological changes of neurons peripheral to the lesion. We explored functional reorganization of cortical retinotopic maps after a focal ischemic lesion in primary visual cortex of kittens using optical imaging of intrinsic signals. After 1, 2, and 5 weeks postlesion (wPL), we addressed whether functional reorganization correlated in time with changes in the expression of MAP-2, GAP-43, GFAP, GABA A receptor subunit ␣1 (GABA A ␣1), subunit 1 of the NMDA receptor (NMDAR1), and in neurotransmitter levels at the border of the lesion. Our results show that: (1) retinotopic maps reorganize with time after an ischemic lesion; (2) MAP-2 levels increase gradually from 1wPL to 5wPL; (3) MAP-2 upregulation is associated with an increase in dendritic-like structures surrounding the lesion and a decrease in GFAP-positive cells; (4) GAP-43 levels reach the highest point at 2wPL; (5) NMDAR1 and glutamate contents increase in parallel from 1wPL to 5wPL; (6) GABA A ␣1 levels increase from 1wPL to 2wPL but do not change after this time point; and (7) GABA contents remain low from 1wPL to 5wPL. This is a comprehensive study showing for the first time that functional reorganization correlates in time with dendritic sprouting and with changes in the excitatory/inhibitory neurotransmission systems previously proposed to participate in cortical remodeling and suggests mechanisms by which plasticity of cortical representations may occur.Key words: plasticity; visual cortex; sprouting; maps; ischemia; injury; imaging techniques; cat; retinotopy; receptors; photochemical lesion; unmasking IntroductionCNS as well as PNS lesions lead to functional deficits, yet recovery of the lost functions may occur over time. It has been proposed that restoration of functions after focal somatosensory and motor cortical damage (Nudo et al., 1996a;Rouiller et al., 1998a;Coq and Xerri, 1999;Rijntjes and Weiller, 2002) may rely, to some degree, on the reorganization of cortical maps. Cortical reorganization has been observed to involve either zones surrounding the lesion area (Castro and Borrell, 1995;Nudo et al., 1996a;Rouiller et al., 1998a;Zepeda et al., 1999Zepeda et al., , 2003 or regions within the homologous contralateral cortex (Jones and Schallert, 1992;Jones et al., 1996;Nudo et al., 1996b;Dijkhuizen et al., 2003).Reorganization of the visual cortex after focal lesions has been studied less until recently despite its clinical relevance. We have previously shown that visual cortex maps reorganize to a certain extent with time after an ischemic lesion (Zepeda et al., 2003), while Eysel and Schweigart (1999) have reported that single cells in the surrounding area of the lesion exhibit enlarged receptive fields. However, neurorepair mechanisms associated with such visual reorganizat...

The prevalence of vitamin D deficiency in the pediatric population has increased in recent years and continues to be underdiagnosed and undertreated. According to data from the "ENSANUT 2006" (National Health and Nutrition Survey), the prevalence of vitamin D deficiency in Mexico was 16% in children aged 2-12 years. Vitamin D plays a critical role in the formation and bone homeostasis and consequently on growth. Its deficiency is clearly associated with diseases such as rickets and osteomalacia, and it has been linked to other diseases such as obesity, metabolic syndrome, diabetes, cancer, respiratory infections and immune system disease. Specific risk groups have been described in the medical literature for vitamin D deficiency in which supplementation may offer a benefit. Currently, there is still controversy in defining the serum levels of proficiency and dose supplementation. In Mexico, the daily suggested intake of vitamin D is 5.6μg (224 IU), which is significantly lower than the recommendations in the U.S. and Europe (i.e., between 400 and 1000 IU/day). An increase in vitamin D deficiency has been reported in recent years. There is no consensus regarding the sufficiency levels of vitamin D. Cut-off values vary from 20 to 30ng/ml. Therefore, the objective of this review was to provide an overview of the problem in the pediatric population and to describe the groups at risk, as well as to analyze the current recommendations for vitamin D supplementation. Vitamin D deficiency was considered rare in Mexico according to the National Institute of Medical Science and Nutrition Salvador Zubirán. Lack of evidence did not help to establish the international recommended daily intake. Currently, vitamin D deficiency must be recognized as a health problem, worthy of attention and action. We suggest that prospective studies are carried out in our country where the relationship between serum vitamin D deficiency and poor bone mineralization will be established.

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