RECTIFICATION NONLINEARITY IN CORTICAL END-STOPPED PERCEPTIVE FIELDS

End-stopped perceptive fields associated with line targets were demons trated previously with length and width Westheimer functions. In this study we investigated rectifying non-linearity in these perceptive fie lds to examine whether they directly reflect the organization of corti cal receptive fields. Specifically, we reversed the polarity of parts of the background field associated with a specific perceptive field su b-region and examined threshold changes in corresponding length or wid th Westheimer functions. Results showed full-wave rectification in end -stopping and half-wave rectification in center summation and flank-in hibition preceding linear summation in end-stopped perceptive fields. Half-wave rectification in center summation and surround-inhibition pr eceding linear summation was also found in circular perceptive fields associated with spot targets. These results are inconsistent with dire ct links between perceptive fields and cortical receptive fields. Rath er they suggest that these perceptive fields are likely the second-ord er fields formed by pooled non-linearly rectified outputs from cortica l receptive fields. (C) 1998 Elsevier Science Ltd. All rights reserved .