Article

Response characteristics of the pigeon's pretectal neurons to illusory contours and motion.

Laboratory for Visual Information Processing, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, P. R. China.
The Journal of Physiology (impact factor: 4.72). 01/2007; 577(Pt 3):805-13. DOI:10.1113/jphysiol.2006.120071 pp.805-13
Source: PubMed

ABSTRACT Misinterpretations of visual information received by the retina are called visual illusions, which are known to occur in higher brain areas. However, whether they would be also processed in lower brain structures remains unknown, and how to explain the neuronal mechanisms underlying the motion after-effect is intensely debated. We show by extracellular recording that all motion-sensitive neurons in the pigeon's pretectum respond similarly to real and illusory contours, and their preferred directions are identical for both contours in unidirectional cells, whereas these directions are changed by 90 deg for real versus illusory contours in bidirectional cells. On the other hand, some pretectal neurons produce inhibitory (excitatory) after-responses to cessation of prolonged motion in the preferred (null) directions, whose time course is similar to that of the motion after-effect reported by humans. Because excitatory and inhibitory receptive fields of a pretectal cell overlap in visual space and possess opposite directionalities, after-responses to cessation of prolonged motion in one direction may create illusory motion in the opposite direction. It appears that illusory contours and motion could be detected at the earliest stage of central information processing and processed in bottom-up streams, and that the motion after-effect may result from functional interactions of excitatory and inhibitory receptive fields with opposite directionalities.

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Keywords

bidirectional cells
 
bottom-up streams
 
central information processing
 
earliest stage
 
extracellular recording
 
functional interactions
 
higher brain areas
 
illusory motion
 
inhibitory receptive fields
 
lower brain structures
 
motion after-effect
 
motion-sensitive neurons
 
neuronal mechanisms
 
null
 
pigeon's pretectum
 
pretectal cell overlap
 
pretectal neurons
 
visual illusions
 
visual information
 
visual space
 

Yu-Qiong Niu