The effects of collinearity and orientation on texture visual evoked potentials

OBJECTIVE The aim of the research was to study the effects of stimulus orientation at both the local (textons) and the global (segregated elements) level on texture visual evoked potentials (tVEPs). METHODS Two tVEP paradigms were presented to 10 volunteers. The paradigms were characterized by alternating uniform textures (random mixture of square dots and lines) and textures in which stripes of randomly disposed lines segregated from a square dots' background. In one paradigm, the stripes were horizontal and in the other, vertical. The lines could be either horizontal or vertical in single stimuli of both paradigms. Thus, two stimuli with local/global collinearity and two stimuli without local/global collinearity were available. tVEPs were derived from Oz referenced to the left earlobe and averaged separately for each condition. Segregation-related components were obtained subtracting the traces without segregation from the traces with segregation. RESULTS A negative segregation component starting at the latency of P1 and extending until the end of N2 characterized the tVEPs, without significant differences among the 4 stimulus conditions. In the presence of local/global collinearity, we found an early modulation of N1 amplitude. This modulation was orientation-dependent, as vertical collinearity increased N1 negativity and horizontal collinearity reduced N1 negativity. CONCLUSIONS Our experiment confirms previous findings about the segregation negativity, which may depend on contextual modulation of V1 neurons by long-range horizontal and feed-back connections. The early effect of collinearity may depend on more local modulatory connections.

[1]  G. Kanizsa,et al.  Organization in Vision: Essays on Gestalt Perception , 1979 .

[2]  Victor A. F. Lamme,et al.  Organization of texture segregation processing in primate visual cortex , 1993, Visual Neuroscience.

[3]  W Singer,et al.  The Perceptual Grouping Criterion of Colinearity is Reflected by Anisotropies of Connections in the Primary Visual Cortex , 1997, The European journal of neuroscience.

[4]  G. Caputo,et al.  Edge detection and surface `filling in' as shown by texture visual evoked potentials , 1999, Clinical Neurophysiology.

[5]  C. Gilbert,et al.  Long-range horizontal connections and their role in cortical reorganization revealed by optical recording of cat primary visual cortex , 1995, Nature.

[6]  D. V. van Essen,et al.  Neuronal responses to static texture patterns in area V1 of the alert macaque monkey. , 1992, Journal of neurophysiology.

[7]  D Purves,et al.  The distribution of oriented contours in the real world. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[8]  Victor A. F. Lamme,et al.  Contextual Modulation in Primary Visual Cortex , 1996, The Journal of Neuroscience.

[9]  B. Julesz.  Textons, the elements of texture perception, and their interactions , 1981, Nature.

[10]  Victor A. F. Lamme,et al.  Texture segregation is processed by primary visual cortex in man and monkey. Evidence from VEP experiments , 1992, Vision Research.

[11]  Victor A. F. Lamme.  The neurophysiology of figure-ground segregation in primary visual cortex , 1995, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[12]  Michael Bach,et al.  Electrophysiological correlates of texture segregation in the human visual evoked potential , 1992, Vision Research.

[13]  D. Hubel,et al.  Receptive fields of single neurones in the cat's striate cortex , 1959, The Journal of physiology.

[14]  G. Caputo,et al.  Amodal completion in texture visual evoked potentials , 1999, Vision Research.

[15]  M. Bach,et al.  Similar Electrophysiological Correlates of Texture Segregation Induced by Luminance, Orientation, Motion and Stereo , 1997, Vision Research.

[16]  C. Gilbert,et al.  Improvement in visual sensitivity by changes in local context: Parallel studies in human observers and in V1 of alert monkeys , 1995, Neuron.

[17]  Clara Casco,et al.  A visual evoked potential correlate of global figure-ground segmentation , 1999, Vision Research.