X-Message-Number: 10911 Date: Sat, 12 Dec 1998 07:54:29 -0500 From: Thomas Donaldson <> Subject: CryoNet #10905 - #10910 Hi everyone! About dendritic spines: It is false that few neuroscientists are interested in them. This hardly means that they are fully understood, but then lots of things about how our brains work aren't fully understood. The importance of dendritic spines is that they contain the receiving sides of a synapse, though not all such receiving sides (synapses aren't always on dendritic spines). They do change with time, also. More than that, good evidence exists that even our SYNAPSES change with time; just how and why is thought now by many neuroscientists to be central to the means by which we form our long term memories. One very plausible idea about spines and how they work is that they isolate a synapse and its chemical environment from the rest of the neuron --- not completely, but partially. That isolation may sometimes be important for messages received on that synapse. I have a list of readings on neurobiology and memory which I'm happy to send by email to anyone who wants it. From what I understand of spines, they are not persistent structures and it is the growth and disappearance of SYNAPSES which gives the main physical expression of memory --- but not in the hippocampus, which processes but does not store any memories for very long. Apparently, even in sleep some of your dendritic spines disappear, possibly to reform again when you reawaken (refs given on request). As for the disappearance of money, Mr. Smith clearly won't listen to any of us, so I don't see the point of further discussion with him. Best and long long life to all, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=10911