Редактирование: Whole brain emulation (раздел)

==== Synapse Identification ====

In electron micrographs, synapses are currently recognized using the criteria that within a 
structure there are synaptic vesicles adjacent to a presynaptic density, a synaptic density with 
electron‐dense material in the cleft and densities on the cytoplasmic faces in the pre‐ and 
postsynaptic membranes (Colonnier, 1981; Peters and Palay, 1996). 
 
One of the major unresolved issues for WBE is whether it is possible to identify the functional 
characteristics of synapses, in particular synaptic strength and neurotransmitter content, from 
their morphology.  
 
In general, cortical synapses tend to be either asymmetrical “type I” synapses (75‐95%) or 
symmetrical “type II” synapses (5‐25%), based on having a prominent or thin postsynaptic 
density. Type II synapses appear to be inhibitory, while type I synapses are mainly excitatory 
(but there are exceptions) (Peters and Palay, 1996). This allows at least some inference of 
function from morphology. 
 
The shape and type of vesicles may also provide clues about function. Small, clear vesicles 
appear to mainly contain small‐molecule neurotransmitters; large vesicles (60 nm diameter) 
with dense cores appear to contain noradrenaline, dopamine or 5‐HT; and large vesicles (up 
to 100 nm) with 50‐70 nm dense cores contain neuropeptides (Hokfelt, Broberger et al., 2000; 
Salio, Lossi et al., 2006). Unfortunately there does not appear to be any further distinctiveness 
of vesicle morphology to signal neurotransmitter type.