title: Speeding up the brain: when spatial facilitation translates into latency shortening.
abstract: Waves of activity following a focal stimulation are reliably observed to spread across the cortical tissue. The origin of these waves remains unclear and the underlying mechanisms and function are still debated. In this study, we ask whether waves of activity modulate the magnetoencephalography (MEG) signals recorded in humans during visual stimulation with Gabor patches sequentially flashed along a vertical path, eliciting a perception of vertical apparent motion. Building upon the functional properties of long-rang horizontal connections, proposed to contribute to spreading activity, we specifically probe the amplitude and latency of MEG responses as a function of Gabor contrast and orientation. The results indicate that in the left hemisphere the response amplitude is enhanced and the half height response latency is shortened for co-aligned Gabor as compared to misaligned Gabor patches at a low but not at a high contrast. Building upon these findings, we develop a biologically plausible computational model that performs a "spike time alignment" of the responses to elongated contours with varying contrast, endowing them with a phase advance relative to misaligned contours.
authors.affiliation: UPMC Univ Paris 06, UMR-S975 UMR 7225, Centre de Recherche en Neuroscience Equipe Cogimage, Paris, France ; Inserm U 975, Centre de Recherche en Neuroscience Equipe Cogimage, Paris, France ; CNRS UMR 7225, Centre de Recherche en Neuroscience Equipe Cogimage, Paris, France ; ICM Equipe Cogimage, Paris, France.
authors.forename: Anne-Lise
authors.initials: AL
authors.lastname: Paradis
authors.forename: Shasha
authors.initials: S
authors.lastname: Morel
authors.forename: Peggy
authors.initials: P
authors.lastname: Seriès
authors.forename: Jean
authors.initials: J
authors.lastname: Lorenceau