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Michelle Howell Young, Richard Heitz, Braden Purcell, Jeffrey Schall, Geoff Woodman; Source localization of an event-related potential indexing covert shifts of attention in macaques. Journal of Vision 2011;11(11):194. doi: 10.1167/11.11.194.
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Although, human event-related potentials (ERP) provide precise temporal resolution of the neural activity underlying covert attentional selection, this method is uninformative about the source of that neural activity within the brain. Previously, we showed that ERPs recorded from macaque monkeys evidence an N2pc component (N2-posterior-contralateral) homologous to that found in human subjects when attention is covertly shifted during visual search (Woodman et al., 2007 PNAS). In the present work, we sought to test the hypothesis that the neural networks generating the monkey N2pc (or m-N2pc) are similar to those of humans. Previous work modeling the neural generators of the human N2pc found that there are two temporally and spatially distinct subcomponents: an initial parietal activation followed by activity in ventral extrastriate cortex (Hopf et al., 2000 Cereb Cortex). In the current study the neural generators of the m-N2pc were modeled using electrophysiological and structural MRI data for electrical source analysis using CURRY 6 (Neuroscan). A 3-D reconstruction of the head and cortical surface was created using the boundary element method. Distributed (current density) and local (dipole) sources were calculated. For the current density analysis Low Resolution Electromagnetic Tomography (LORETA) was used. Local source analyses were modeled with a single moving dipole. Both methods indicated a source in extrastriate visual cortex, generally corresponding to the human data but with a unique temporal sequence.
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