A theory of the Benham Top based on center-surround interactions in the parvocellular pathway.
A model color-opponent neuron was used to investigate the subjective colors evoked by the Benham Top (BT). Color-opponent inputs from cone-selective parvocellular (P) pathway neurons with center-surround receptive fields were subtracted with a short relative delay, yielding a small transient input in response to a white spot. This transient input was amplified by BT-like stimuli, modeled as a thin dark bar followed by full-field illumination. The narrow bar produced maximal activation of the P-pathway surrounds but only partial activation of the P-pathway centers. Due to saturation, subsequent removal of the bar had little effect on the P-pathway surrounds, whereas the transient input from the P-pathway centers was amplified via disinhibition. Responses to BT-like stimuli became weaker as surround sensitivity recovered, producing an effect analogous to the progression of perceived BT colors. Our results suggest that the BT-illusion arises because cone-selective neurons convey information about both color and luminance contrast, allowing the two signals become confounded.
Kenyon
Garrett T
GT
P-21, Biological and Quantum Physics, MS D454, Los Alamos National Laboratory, Los Alamos, NM 87545, USA. gkenyon@lanl.gov
Hill
Dan
D
Theiler
James
J
George
John S
JS
Marshak
David W
DW
D000818:Animals; D003118:Color Perception / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000502:physiology; D006801:Humans; D008959:Models, Neurological; D009039:Motion Perception / Q000502:physiology; D009474:Neurons / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time; D013997:Time Factors; D014793:Visual Cortex / Q000166:cytology / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*; D014795:Visual Pathways / Q000166:cytology / Q000502:physiology*