就像蒲公英定時(shí)釋放種子一樣,，海馬突觸中神經(jīng)遞質(zhì)的釋放也有特定的釋放幾率,。盡管釋放幾率是衡量突觸效能的基礎(chǔ)指標(biāo)，但是,，突觸是如何控制神經(jīng)遞質(zhì)的釋放目前還不為人們所知,。
在8月14日的《神經(jīng)元》（Neuron）雜志上，Branco等人通過(guò)研究連接一對(duì)海馬神經(jīng)元的突觸前終末,，發(fā)現(xiàn)同一樹(shù)突分支的相鄰?fù)挥|有著相似的神經(jīng)遞質(zhì)釋放幾率,，該釋放幾率與樹(shù)突分支上的突觸數(shù)目呈負(fù)相關(guān)。
該項(xiàng)研究成果表明,，樹(shù)突的活性決定了突觸釋放神經(jīng)遞質(zhì)的幾率,，樹(shù)突的這種負(fù)反饋?zhàn)饔每赡芫哂姓{(diào)節(jié)突觸與樹(shù)突的作用距離的功能。（生物谷Bioon.com）
生物谷推薦原始出處：
Neuron,，Vol 59, 475-485, 14 August 2008,，Tiago Branco, Yukiko Goda
Local Dendritic Activity Sets Release Probability at Hippocampal Synapses
Tiago Branco,1,2, Kevin Staras,1,3 Kevin J. Darcy,1 and Yukiko Goda1,2
The arrival of an action potential at a synapse triggers neurotransmitter release with a limited probability, pr. Althoughpr is a fundamental parameter in defining synaptic efficacy, it is not uniform across all synapses, and the mechanisms by which a given synapse sets its basal release probability are unknown. By measuring pr at single presynaptic terminals in connected pairs of hippocampal neurons, we show that neighboring synapses on the same dendritic branch have very similar release probabilities, and pr is negatively correlated with the number of synapses on the branch. Increasing dendritic depolarization elicits a homeostatic decrease in pr, and equalizing activity in the dendrite significantly reduces its variability. Our results indicate that local dendritic activity is the major determinant of basal release probability, and we suggest that this feedback regulation might be required to maintain synapses in their operational range.
