title: Linking cortical visual processing to viewing behavior using fMRI.
abstract: One characteristic of natural visual behavior in humans is the frequent shifting of eye position. It has been argued that the characteristics of these eye movements can be used to distinguish between distinct modes of visual processing (Unema et al., 2005). These viewing modes would be distinguishable on the basis of the eye-movement parameters fixation duration and saccade amplitude and have been hypothesized to reflect the differential involvement of dorsal and ventral systems in saccade planning and information processing. According to this hypothesis, on the one hand, while in a "pre-attentive" or ambient mode, primarily scanning eye movements are made; in this mode fixation are relatively brief and saccades tends to be relatively large. On the other hand, in "attentive" focal mode, fixations last longer and saccades are relatively small, and result in viewing behavior which could be described as detailed inspection. Thus far, no neuroscientific basis exists to support the idea that such distinct viewing modes are indeed linked to processing in distinct cortical regions. Here, we used fixation-based event-related (FIBER) fMRI in combination with independent component analysis (ICA) to investigate the neural correlates of these viewing modes. While we find robust eye-movement-related activations, our results do not support the theory that the above mentioned viewing modes modulate dorsal and ventral processing. Instead, further analyses revealed that eye-movement characteristics such as saccade amplitude and fixation duration did differentially modulate activity in three clusters in early, ventromedial and ventrolateral visual cortex. In summary, we conclude that evaluating viewing behavior is crucial for unraveling cortical processing in natural vision.
authors.affiliation: NeuroImaging Center, University Medical Center Groningen Groningen, Netherlands ; Laboratory for Experimental Ophthalmology, University Medical Center Groningen Groningen, Netherlands.
authors.forename: Jan Bernard C
authors.initials: JB
authors.lastname: Marsman
authors.affiliation: NeuroImaging Center, University Medical Center Groningen Groningen, Netherlands.
authors.forename: Remco
authors.initials: R
authors.lastname: Renken
authors.affiliation: Laboratory for Experimental Ophthalmology, University Medical Center Groningen Groningen, Netherlands ; Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour Nijmegen, Netherlands.
authors.forename: Koen V
authors.initials: KV
authors.lastname: Haak
authors.affiliation: Laboratory for Experimental Ophthalmology, University Medical Center Groningen Groningen, Netherlands.
authors.forename: Frans W
authors.initials: FW
authors.lastname: Cornelissen
keywords: dorsal stream; eye movements; fMRI; fixation-based event related fMRI; independent component analysis; natural viewing behavior; scene perception; ventral stream