Independent Rules for Synaptic Plasticity

[Patrick Thomas]

I wonder who is currently supporting the idea of independent (non hebbian)
rules for synaptic plasticity apart from Finkel & Edelman (1). They formulated
a synaptic plasticity mechanism which is based on a PRESYNAPTIC RULE
(the efficacy of the presynaptic terminal is dependent only on the activity
of the presynaptic neuron, no postsynaptic firing or above-treshold
depolarization is necessary, ALL presynaptic terminals are affected) and on
a POSTSYNAPTIC RULE which is a  heterosynaptic modification rule similiar
to that of Changeux and others.

Unfortunately there is strong evidence that a hebbian condition is
necessary for modifications of synaptic efficacy (cf 2,3). Even the
experiment by Bonhoeffer et al which demonstrated the non-locality
of hebbian modification (all presynaptic terminals are likewise
enhanced although only one postsynaptic neuron is depolarized) only
occured when the hebbian condition was fulfilled.

Could someone provide references to work either crushing the idea of
independent modification rules or supporting it ?

Thanx in advance.

Patrick Thomas
Computer Science, Munich Technical University

(1) "Synaptic Function", Edelman/Gall/Cowan (eds), Wiley, 1987.
(2) "Hebbian Synapses in Hippocampus", Kelso et al, PNAS, 83:5326-5330.
(3) Bonhoeffer et al, PNAS, 86:8113-8117.

PS: Bad timing. I bet everyone is in San Diego.