SPINULES - A CASE FOR RETINAL SYNAPTIC PLASTICITY

被引:98
作者
WAGNER, HJ [1 ]
DJAMGOZ, MBA [1 ]
机构
[1] UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,DEPT BIOL,NEUROBIOL GRP,LONDON SW7 2AZ,ENGLAND
基金
英国惠康基金;
关键词
D O I
10.1016/0166-2236(93)90155-F
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
In both vertebrate and invertebrate nervous systems, a population of synapses is characterized by having finger-like indentations of the postsynaptic membrane that project into the presynaptic terminal. These 'spinules' are often transitory structures, and their presence has been associated with increased synaptic activity. We have studied the functional role of spinules in the fish retina, where they are observed in horizontal cells invaginating cone pedicles, and in synaptic terminals of bipolar cells. In the cone-horizontal cell synaptic complex, spinules are present during light adaptation; their formation is triggered by external light stimuli as well as by endogenous factors. Pharmacologically, spinules are degraded following an increase, and formed in response to a decrease of the transmitter glutamate released by the cone cells. Dopamine, released by interplexiform cells and acting via a D1 receptor-mediated increase in cAMP, and a protein-kinase-C-based mechanism are also capable of inducing spinule formation. Functionally, the presence and absence, as well as the timecourse, of spinule formation during light adaptation is closely correlated with the development of biphasic chromatic responses in a class of cone horizontal cells and the manifestation of colour-opponency In ganglion cells. This suggests that in the outer retina of fish, spinules are mediating feedback activity essential for the coding of antagonistic colour information.
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页码:201 / 206
页数:6
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