Abstract
In order to segment figures from their backgrounds it has long been known that our visual system uses the texture information at object borders that is produced by discontinuities along features such as orientation or color (Nothdurft, 1985a-b, 1993, 1994). Nevertheless, the neural basis of texture segmentation remains unclear. Recent studies, however, suggest that this task elicits responses in V1 along with a cascade of feedforward and feedback responses across the visual hierarchy (Thielscher, 2008; Hupe et al., 1999). To study the developmental trajectory of the neural mechanisms involved in texture-defined figure/ground segmentation and their modulation by attention, we recorded high-density visual evoked potentials (VEPs) in children (6–10 years), teens (13–15 years) and in adults (18 and above) to synthetic images portraying simple texture-defined figures. The VEP elicited by the appearance of a texture defined shape had a peak response appearing at about 157 ms for children, 131 ms for teens and 115 ms for adults. Scalp topographies of the peak responses show spatially constrained activity in medial areas in children while these peak responses are progressively more lateral in teens and adults. Even in teens the location of the peak responses on the scalp does not match the adult pattern. This difference in topography, combined with the faster response latency in adults as compared with teens, suggests that there is a protracted development of the cortical areas underlying texture-defined shape segmentation.
Promising Investigator Research Award.