Size matters: MEG empirical and simulation study on source localization of the earliest visual activity in the occipital cortex

Abstract While the relationship between sensory stimulation and tasks and the size of the cortical activations is generally unknown, the visual modality offers a unique possibility of an experimental manipulation of stimulus size-related increases of the spatial extent of cortical activation even during the earliest activity in the retinotopically organized primary visual cortex. We used magnetoecephalography (MEG), visual stimuli of increasing size, and numerical simulations on realistic cortical surfaces to explore the effects of increasing spatial extent of the activated cortical sources on the neuromagnetic fields, location estimation biases, and source resolution. Source localization was performed assuming multiple dipoles in a sphere model using an efficient, automatically restarted multi-start simplex minimizer within the Calibrated Start SpatioTemporal (CSST) algorithm. We found size-related effects on amplitude and latencies and differences in relative locations of the earli...

• Type: Journal
• Year: 2011
• Where: MBEC
• Authors: Sanja Josef Golubic, Ana Susac, Veljko Grilj, Douglas Ranken, Ralph Huonker, Jens Haueisen, Selma Supek
• Keywords: Communications, Human Visual Cortex, MBEC 2011, Primary Visual Cortex, Visual Modality