convergence times

[Christof Koch]

The problem with graded interaction in the brain, mediated through dendro-
dendritic synapses, is that for the most part they don't seem to exist
in cortex proper. In the retina, in the thalamus, in the brain stem etc.
but not in cortex. Yes, the hippocampus has some, in particular in young
animals, but its certainly not a wide-spread phenomena. This leaves
action-potentials or much slower active or passive transport mechanisms.
 
Christof