Olfactory Bulb Plasticity
In neural network, potential for long-lasting modifications of functional characteristics is present. This capacity, known as neural plasticity, attracts attention of many neuroscientists. So there are numerous studies about the influence of pre- and postnatal experience on cellular differentiation and the formation of synaptic connexions as well as those about the neurobiology of learning and memory. Well-known examples of neural plasticity are the modifications in the visual cortex of kittens, appearing after a temporary unilateral eye closure (Wiesel and Hubel, 1963), and the long-term potentiation (LTP) in the hippocampus (Bliss and Lomo, 1973; Teyler and Di Scenna, 1987). In the latter case, early experiments showed that a brief high frequency stimulation of excitatory hippocampal afferences induces a long-lasting increase in synaptic transmission. Supported by findings of subsequent investigations, this form of cellular plasticity is now considered as a good candidate for transient storage of information. Surprisingly, even after extensive studies two major questions remain open. 1) Is the induction of hippocampal LTP required for acquisition?. 2) Is maintenance of the LTP necessary for retention of information? As it is not easy to find a learning paradigm in which hippocampal formation is specifically involved, these questions have been addressed in very few experiments. Recent advances suggest that hippocampus is involved in spatial memory (Barnes, 1988). In this context, some authors tried to correlate LTP and animal’s performances (Mc Naugton et al., 1986; Morris et al., 1986). They found that normal improvement of animal’s performances over days necessitates the development of LTP.
KeywordsSucrose Ethyl Noradrenaline NMDA Acetylcholine
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