The effect of disrupting the human magnocellular pathway on global motion perception

Purpose: To determine the effect of human magnocellular (M) pathway disruption on global motion perception. Method: Thirty adults completed a global motion task under four conditions. The task was completed after adaptation to full-field sinusoidal flicker (experimental condition #1), after adaptation to a gray field (control condition #1), in the presence of a red background (experimental condition #2) and in the presence of a gray background (control condition #2). Based on lesion studies and the physiological properties of single cells in the subcortical M pathway, it was predicted that the psychophysical techniques use in both experimental conditions would disrupt normal functioning of this pathway and result in elevated motion coherence thresholds. Results: Adaptation to flicker and the presence of a red background increased motion coherence thresholds. The threshold elevation was greater when participants were adapted to flicker. Conclusion: Flicker adaptation and the presence of a red background are assumed to temporarily disrupt the M pathway at a subcortical level. The fact that these techniques elevate motion coherence thresholds suggests that the subcortical M pathway is needed for normal human motion perception.Medicine, Faculty ofGraduat