Data from: Laminar microcircuitry of visual cortex producing attention-associated electric fields

Cognitive operations are widely studied by measuring electric fields
through EEG and ECoG. However, despite their widespread use, the neural
circuitry giving rise to these signals remains unknown because the
functional architecture of cortical columns producing attention-associated
electric fields has not been explored. Here, we detail the laminar
cortical circuitry underlying an attention-associated electric field
measured over posterior regions of the brain in humans and monkeys. First,
we identified visual cortical area V4 as one plausible contributor to this
attention-associated electric field through inverse modeling of cranial
EEG in macaque monkeys performing a visual attention task. Next, we
performed laminar neurophysiological recordings on the prelunate gyrus and
identified the electric-field-producing dipoles as synaptic activity in
distinct cortical layers of area V4. Specifically, activation in the
extragranular layers of cortex resulted in the generation of the
attention-associated dipole. Feature selectivity of a given cortical
column determined the overall contribution to this electric field. Columns
selective for the attended feature contributed more to the electric field
than columns selective for a different feature. Last, the laminar profile
of synaptic activity generated by V4 was sufficient to produce an
attention-associated signal measurable outside of the column. These
findings suggest that the top-down recipient cortical layers produce an
attention-associated electric field that can be measured extracortically
with the relative contribution of each column depending upon the
underlying functional architecture.