Neural correlates of illusory line motion.
Illusory line motion (ILM) refers to a motion illusion in which a flash at one end of a bar prior to the bar's instantaneous presentation or removal results in the percept of motion. While some theories attribute the origin of ILM to attention or early perceptual mechanisms, others have proposed that ILM results from impletion mechanisms that reinterpret the static bar as one in motion. The current functional magnetic resonance imaging study examined participants while they made decisions about the direction of motion in which a bar appeared to be removed. Preceding the instantaneous removal of the bar with a flash at one end resulted in a motion percept away from the flash. If this flash and the bar's removal overlapped in time, it appeared that the bar was removed towards the flash (reverse ILM). Independent of the motion type, brain responses indicated activations in areas associated with motion (MT+), endogenous and exogenous attention (intraparietal sulcus, frontal eye fields, and ventral frontal cortex), and response selection (ACC). ILM was associated with lower percept scores and higher activations in ACC relative to real motion, but no differences in shape-selective areas emerged. This pattern of brain activation is consistent with the attentional gradient model or bottom-up accounts of ILM in preference to impletion.
Cognitive Neuroscience Research Group, School of Psychology, The University of Auckland, Auckland, New Zealand.
Jeff P
JP
Hamm
Centres for Aging Research & Human Learning and Development, Department of Psychology, Lancaster University, Lancaster, United Kingdom.
Trevor J
TJ
Crawford
Study Programme Psychology, University of Regensburg, Regensburg, Germany.
Helmut
H
Nebl
Manchester Medical School, Manchester, United Kingdom.
Matthew
M
Kean
Centre for Neuroimaging Sciences, Institute of Psychiatry, King's College London, London, United Kingdom.
Steven C R
SC
Williams
Department of Psychology, University of Bonn, Bonn, Germany.
Ulrich
U
Ettinger
D000328:Adult; D001288:Attention / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D007088:Illusions / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008960:Models, Psychological; D009039:Motion Perception / Q000502:physiology*