1,720,964 research outputs found
Developmental shift from long-term depression to long-term potentiation at the mossy fibre synapses in rat hippocampus
No full textDuring development, in the CA1 hippocampal region, long-term potentiation (LTP) starts appearing at postnatal (P) day 7 and reaches its maximal expression towards the end of the second postnatal week. However, LTP is often preceded by long-term depression (LTD), an activity-dependent and long-lasting reduction of synaptic strength. LTD can be induced by sustained, low-frequency stimulation of the afferent pathway and is dependent on activation of N-methyl-D-aspartate (NMDA) receptors. We report here that, in the CA3 hippocampal region, during a critical period of postnatal development, between P6 and P14, a high-frequency stimulation train (100 Hz, 1 s) to the mossy fibres in the presence of the NMDA receptor antagonist (+)-3-(2-carboxy-piperazin-4-yl)-propyl-1-phosphonic acid (CPP; 20 μM) induced LTD. The depression of the amplitude of the field excitatory postsynaptic potential (EPSP) was 28 ± 7% (n= 21). This form of LTD was NMDA-independent and synapse-specific. When a tetanus was applied in the presence of CPP and 6-cyano-7-nitroquinoxaline-2, 3-dione (CNQX; 50 μM), which blocked the field EPSP, it failed to induce LTD upon washout of CNQX. LTD was probably postsynaptic in origin since it did not affect paired-pulse facilitation. A rise in extracellular calcium concentration (from 2 to 4 mM) produced LTP instead of LTD. At the end of the second postnatal week, the same high-frequency stimulation train to the mossy fibres induced LTP as in adult neurons. Functional changes in synaptic connections during development may control membrane depolarization and the amount of intracellular calcium necessary to trigger either LTD or LTP
The Child with Cerebral Palsy and Visual Impairment
No full textIn recent years, there has been growing evidence in literature reporting the impact visual impairment has on the everyday functioning skills of children with cerebral palsy.
Visual impairment may indeed be present at different levels of severity, and its addition compromises significantly the child’s neurodevelopment. A recent systematic review indicated that, according to the World Health Organization’s International Statistical Classification of Diseases and Related Health Problems (ICD-10), one child in ten with cerebral palsy has some form of severe visual impairment or blindness.
The central role of vision in the child’s growth is highlighted here as well as the definition of visual impairment and its main characteristics in the child with cerebral palsy.
The peculiarities of children with cerebral palsy and visual impairment are considered here in order to determine how the therapist may contribute significantly to their development and the quality of their daily life when a comprehensive and nurturing approach is adopted.
Steps from assessment to care and intervention are illustrated, always emphasizing the distinctiveness of each and every child and the importance of a relational approach and of continuous attention to the child and to the family. Furthermore, the role of an enriched and visually facilitating environment is discussed as well as the importance of posture in promoting visual function. An overview on rehabilitative tools is finally considered, focusing on their application in the support and rehabilitation of children with visual impairment and multiple disabilities
Significance of an integrated rehabilitative approach: case report of a child with cortical visual impairment in cerebral palsy
No full textMuscle eye brain disease: case report
No full textThe objective of this presentation is to describe a case of an
Italian child with muscle eye brain (MEB) disease. It is known
from the literature that MEB is a rare congenital muscular
dystrophy, which until now has been described mostly in
Northern European countries, especially Finland. It is characterized
by hypotonia, muscular weakness, and learning
disability. The visual impairment consists in severe myopia,
retinal degeneration, and optic atrophy. MRI shows brain
malformation of a cobblestone-like cortex and hypoplasic
pons; the visual evoked potentials are significantly high. A
child, diagnosed with Santavuori disease, presented at our
centre when she was 7 months old. The baby was very hypotonic
and she was not rolling, nor sitting, and was not interested
in anything except in her hands and feet. Ocular
findings showed a retinal detachment in the left eye and a
corioretinic atrophy in the right one. A rehabilitative project
commenced which focused on sensory (especially visual)
functions, started. The aim was to integrate sensory and
motor skills. In these two years, despite the slowness of the
progresses, the child has made quite a few improvements.
She is now 33 months old and is able to go on all fours and to
make a few steps alone, especially to reach her mother. She
now appears more motivated to explore the environment to
look for her preferred toys; she also understands and
responds to simple requests made by the therapist. She is
able to organize the first simple constructive movements of
the hands, even if she still prefers to play on the light-box.
She is increasing in using both hands and recently started to
play with a doll. She also began to show interest in images on
an adapted screen of a personal computer and recognized an
image imitating the movement on the screen. In conclusion,
even if psychomotor delay is still present, we think that early
rehabilitation is important to help the child have the best
quality of life compatible with the disease
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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