X-Message-Number: 13239 Date: Thu, 10 Feb 2000 17:28:33 -0500 From: Jan Coetzee <> Subject: Trends in Neurosciences Trends in Neurosciences, 2000, 23:2:53-57 Abstract The recent advent of novel high-resolution imaging methods has created a flurry of exciting observations that address a century-old question: what are biological signals that regulate formation and elimination of dendritic spines? Contrary to the traditional belief that the spine is a stable storage site of long-term neuronal memory, the emerging picture is of a dynamic structure that can undergo fast morphological variations. Recent conflicting reports on the regulation of spine morphology lead to the proposal of a unifying hypothesis for a common mechanism involving changes in postsynaptic intracellular Ca2+ concentration, [Ca2+]i: a moderate rise in [Ca2+]i causes elongation of dendritic spines, while a very large increase in [Ca2+]i causes fast shrinkage and eventual collapse of spines. This hypothesis provides a parsimonious explanation for conflicting reports on activity-dependent changes in dendritic spine morphology, and might link these changes to functional plasticity in central neurons. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=13239