Abstract
We investigated the neural basis of conjoined processing of color and spatial frequency with functional magnetic resonance imaging (fMRI). A multivariate classification algorithm was trained to differentiate between either isolated color or spatial frequency differences, or between conjoint differences in both feature dimensions. All displays were presented in a singleton search task, avoiding confounds between conjunctive feature processing and search difficulty that arose in previous studies contrasting single feature and conjunction search tasks. Based on patient studies, we expected the right temporo-parietal junction (TPJ) to be involved in conjunctive feature processing. This hypothesis was confirmed in that only conjoined color and spatial frequency differences, but not isolated feature differences could be classified above chance level in this area. Furthermore, a race model inequality test applied to the accuracy values of the identified voxels within TPJ revealed that the accuracy of a classification of differences in both feature dimensions was superadditive compared to the classification accuracies of isolated color or spatial frequency differences. In addition, superior parietal representation of feature conjunction, reported previously by our group (Baumgartner et al., 2013) could be replicated. These data provide evidence for the processing of feature conjunctions, here color and spatial frequency in right TPJ, in addition to superior parietal cortex. References: Baumgartner, F., Hanke, M., Geringswald, F., Zinke, W., Speck, O. & Pollmann, S. (2013). Evidence for feature binding in the superior parietal lobule. Neuroimage, 68, 173-180.
Meeting abstract presented at VSS 2014