Basis profile curve identification to understand electrical stimulation effects in human brain networks
Fig 1
Cortico-cortical evoked potential analysis paradigms.
A: Convergent—Evoked responses at one chosen site (gray circle) are compared with the effect of stimulating all other sites (yellow circles with lightning bolt). For N electrodes, this characterizes N interactions. B: Divergent—The temporal response of all sites are examined and compared in response to stimulation of a chosen site (N interactions). C: All-to-all—All N2 interactions between sites are characterized. D: Hypothesis preselected—Two sites are chosen based upon a pre-defined anatomical or functional hypothesis, and a 1-way or 2-way interaction between them is characterized. E: In the convergent paradigm, all measured responses from a brain surface electrode are associated with the same underlying laminar architecture, so each response shape measured implies a distinct type of input. F: In the divergent paradigm, different shaped responses may be measured from different sites, in response to stimulation at a single site. This creates ambiguity because different shaped responses cannot distinguish between 1) the same type of output arriving at cortical sites with different underlying laminar architecture and 2) different types of inputs to sites with similar laminar architecture.