Not much is known about what silica pathways are, but Commander Adama compares them to a brain of sorts for Cylons when he confronts Leoben Conoy within the bowels of Ragnar Anchorage in the Mini-Series.
Apparently, they are affected by the radiation generated by cosmic storms, such as the one surrounding Ragnar Anchorage. Although these affects are not immediate, they do usually occur within the space of hours after initial exposure. Humans appear to experience no symptoms; only Cylons are affected). While the Colonial military picked this location for the depot based on the mechanical Cylon Centurion Model 0005 and similiar models from the Cylon War, it was fortuitous that the Humano-Cylon models were also affected by the storm radiation as well. It is unknown whether the mechanical Cylon models would be affected in a faster fashion.
Through observations of what happened to the Leoben and Aaron Doral copies after their extended stays within the station, symptoms seem to include elements of headache, nausea, and some level of fever or other heat-producing symptom (Humano-Cylons do sweat (Flesh and Bone)).