Data from: Resolving the mesoscopic missing link: biophysical modeling of EEG from cortical columns in primates

Event-related potentials (ERP) are among the most widely measured indices
for studying human cognition. While their timing and magnitude provide
valuable insights, their usefulness is limited by our understanding of
their neural generators at the circuit level. Inverse source localization
offers insights into such generators, but their solutions are not unique.
To address this problem, scientists have assumed the source space
generating such signals comprises a set of discrete equivalent current
dipoles, representing the activity of small cortical regions. Based on
this notion, theoretical studies have employed forward modeling of scalp
potentials to understand how changes in circuit-level dynamics translate
into macroscopic ERPs. However, experimental validation is lacking because
it requires in vivo measurements of intracranial brain sources. Laminar
local field potentials (LFP) offer a mechanism for estimating intracranial
current sources. Yet, a theoretical link between LFPs and intracranial
brain sources is missing. Here, we present a forward modeling approach for
estimating mesoscopic intracranial brain sources from LFPs and predict
their contribution to macroscopic ERPs. We evaluate the accuracy of this
LFP-based representation of brain sources utilizing synthetic laminar
neurophysiological measurements and then demonstrate the power of the
approach in vivo to clarify the source of a representative cognitive ERP
component. To that end, LFP was measured across the cortical layers of
visual area V4 in macaque monkeys performing an attention demanding task.
We show that area V4 generates dipoles through layer-specific
transsynaptic currents that biophysically recapitulate the ERP component
through the detailed forward modeling. The constraints imposed on EEG
production by this method also revealed an important dissociation between
computational and biophysical contributors. As such, this approach
represents an important bridge between laminar microcircuitry, through the
mesoscopic activity of cortical columns to the patterns of EEG we measure
at the scalp.