Linked Life Data

9464925

Source:http://linkedlifedata.com/resource/pubmed/id/9464925

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
1998-3-20
pubmed:abstractText
Long-term changes of synaptic efficacy, in particular when they are use-dependent, are candidate mechanisms for the storage of information in the nervous system. In a variety of brain structures, including the neocortex and hippocampus, synapses are susceptible to long-term potentiation (LTP) and long-term depression (LTD). It has been hypothesized that the polarity of the synaptic gain change depends on the amplitude of the postsynaptic [Ca2+]i rise, the threshold for the induction of LTD being lower than that for the induction of LTP. To test this assumption, we characterized Ca2+ signals in layer II/III pyramidal cells of rat visual cortex slices, using the fluorescent Ca2+ indicator fura-2, during application of stimulation protocols that had been adjusted to reliably induce either LTP or LTD in cells not loaded with fura-2. At dendritic sites activated by the stimulated afferents the intracellular [Ca2+] concentration ([Ca2+]i) reached higher amplitudes and decayed more slowly with stimuli inducing LTP than with those inducing LTD. To directly analyse the functional significance of the observed difference in the Ca2+ signal amplitude, we examined whether a tetanization protocol suitable for the induction of LTP can be converted into a protocol inducing LTD by injecting the postsynaptic cells with Ca2+ chelators that reduce the concentration of effective free Ca2+. In the presence of fura-2 or BAPTA [bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetate], the stimulation protocol that would normally produce LTP induced either LTD or failed to induce synaptic modifications altogether. These results support the hypothesis that the amplitude of the postsynaptic rise in [Ca2+]i is a key factor in the determination of the polarity of synaptic gain change.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0953-816X
pubmed:author
pubmed:issnType
Print
pubmed:volume
9
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2309-22
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Relation between dendritic Ca2+ levels and the polarity of synaptic long-term modifications in rat visual cortex neurons.
pubmed:affiliation
Max Planck Institute for Brain Research, Frankfurt, Germany.
pubmed:publicationType
Journal Article, In Vitro