Abstract
To date, the neural mechanisms of feature information integration across saccades, also known as trans-saccadic integration (TSI), of low-level object features are relatively unknown. Using fMRI adaptation (fMRIa), we found that the right inferior parietal lobule (IPL; specifically, SMG) and extrastriate cortex (putative V4) are sensitive to stimulus orientation in a space-fixed reference frame (Dunkley & Crawford, Society for Neuroscience Abstracts, 2012). To identify the neural mechanisms of underlying TSI in multiple reference frames, we employed fMRIa to probe three spatial conditions: 1) Space-fixed, 2) Retina-fixed and 3) Frame-independent (neither Space-fixed, nor Retina-fixed). Functional data were collected across 12 participants while they observed an obliquely oriented grating (45° or 135°), followed by a grating at the same (‘Repeat’ condition) or different angle (‘Novel’ condition). Participants were instructed to decide via 2AFC if the subsequent grating was repeated or novel. Repeat vs. Novel contrasts showed repetition suppression (RS) and enhancement (RE). RS showed condition-specific patterns within a parieto-frontal network. Distinct areas of activation were identified for the three conditions (i.e., SMG for Condition 1; middle and inferior frontal gyri (MFG, IFG) for Condition 2; and FEF and area 7 for Condition 3) as well as common clusters (i.e., posterior middle intraparietal sulcus, M1 and pre-supplementary area). RE was observed in occipito-temporal areas. Specifically, RE in Condition 1 was observed in cuneus, inferior occipital gyrus, medial occipitotemporal gyrus (MOtG), lateral occipitotemporal gyrus (LOtG) and MFG. RE in Condition 2 was observed in lingual gyrus (LG) and MOtG. In Condition 3, RE was found in cuneus, LOtG, middle occipital gyrus and LG. Shared RE areas included cuneus, LG and MOtG. Overall, TSI of orientation activated different cortical patterns (with some parietal overlap) in the three frames. Further, suppression occurred in a ‘cognitive-sensorimotor,’ parieto-frontal network, whereas enhancement occurred in an ‘early visual,’ occipital network.
Meeting abstract presented at VSS 2015