Priming of first- and second-order motion: mechanisms and neural substrates.
Priming for luminance-modulated (first-order) motion has been shown to rely on the functional integrity of visual area V5/MT [Campana, G., Cowey, A., & Walsh, V. (2002). Priming of motion direction and area V5/MT: A test of perceptual memory. Cerebral Cortex, 12, 663-669; Campana, G., Cowey, A., & Walsh, V. (2006). Visual area V5/MT remembers "what" but not "where". Cerebral Cortex, 16, 1766-1770]. The high retinotopical organization of this area would predict that direction priming is sensitive to spatial position. In order to test this hypothesis, and to see whether a similar priming mechanism also exists with second-order motion, we tested motion direction priming and its interaction with spatial position with both first- and second-order motion. Indeed, whereas a number of studies have pinpointed the specific mechanisms and neural substrates for these two kinds of motion perception that appear to be (partially) non-overlapping (i.e., Lu, Z. L., & Sperling, G. (2001). Three-systems theory of human visual motion perception: Review and update. Journal of the Optical Society of America A, 18, 2331-2370; Vaina, L. M., & Soloviev, S. (2004). First-order and second-order motion: Neurological evidence for neuroanatomically distinct systems. Progress in Brain Research, 144, 197-212), the mechanisms and neural substrates mediating implicit memory for first- and second-order motion are still unknown. Our results indicate that priming for motion direction occurs not only with first-order but also with second-order motion. Priming for motion direction is position-sensitive both with first- and second-order motion, suggesting for both processes a locus of representation where retinotopicity is still maintained, that is within the V5/MT complex but earlier than MST. Cross-order motion priming also exists but is not sensitive to spatial position, suggesting that the locus where processing of first- and second-order motion converge is situated in MST or beyond.
Campana
Gianluca
G
Dipartimento di Psicologia Generale, Università di Padova, Via Venezia 8, 35131 Padova, Italy. gianluca.campana@unipd.it
Pavan
Andrea
A
Casco
Clara
C
D000328:Adult; D001143:Arousal / Q000502:physiology*; D003463:Cues; D004192:Discrimination, Psychological / Q000502:physiology*; D006801:Humans; D008027:Light; D009039:Motion Perception / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D012016:Reference Values; D015398:Signal Transduction / Q000502:physiology; D013028:Space Perception / Q000502:physiology*; D014793:Visual Cortex / Q000166:cytology / Q000502:physiology*