Please find detailed methodology as well as relevant references in the supplement to this abstract.
Arieli A, Sterkin A, Grinvald A, Aertsen A: Dynamics of ongoing activity: explanation of the large variability in evoked cortical responses. Science. 1996, 273: 1868-1871. 10.1126/science.273.5283.1868.
Churchland MM, Yu BM, Cunningham JP, Sugrue LP, Cohen MR, Corrado GS, Newsome WT, Clark AM, Hosseini P, Scott BB: Stimulus onset quenches neural variability: a widespread cortical phenomenon. Nature Neurosci. 2009.