title: Covert shifts of spatial attention in the macaque monkey.
abstract: In the awake state, shifts of spatial attention alternate with periods of sustained attention at a fixed location or object. Human fMRI experiments revealed the critical role of the superior parietal lobule (SPL) in shifting spatial attention, a finding not predicted by human lesion studies and monkey electrophysiology. To investigate whether a potential homolog of the human SPL shifting region exists in monkeys (Macaca mulatta), we adopted an event-related fMRI paradigm that closely resembled a human experiment (Molenberghs et al., 2007). In this paradigm, a pair of relevant and irrelevant shapes was continuously present on the horizontal meridian. Subjects had to covertly detect a dimming of the relevant shape while ignoring the irrelevant dimmings. The events of interest consisted of the replacement of one stimulus pair by the next. During shift but not stay events, the relevant shape of the new pair appeared at the contralateral position relative to the previous one. Spatial shifting events activated parietal areas V6/V6A and medial intraparietal area, caudo-dorsal visual areas, the most posterior portion of the superior temporal sulcus, and several smaller frontal areas. These areas were not activated during passive stimulation with the same sensory stimuli. During stay events, strong direction-sensitive attention signals were observed in a distributed set of contralateral visual, temporal, parietal, and lateral prefrontal areas, the vast majority overlapping with the sensory stimulus representation. We suggest medial intraparietal area and V6/V6A as functional counterparts of human SPL because they contained the most widespread shift signals in the absence of contralateral stay activity, resembling the functional characteristics of the human SPL shifting area.
authors.affiliation: Laboratory for Neuro-and Psychophysiology, KU Leuven Medical School, 3000 Leuven, Belgium, Laboratory for Cognitive Neurology, Neurosciences Department, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Natalie
authors.identifier: http://orcid.org/0000-0001-8896-8953
authors.initials: N
authors.lastname: Caspari
authors.affiliation: Laboratory for Neuro-and Psychophysiology, KU Leuven Medical School, 3000 Leuven, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Janssens
authors.affiliation: Laboratory for Neuro-and Psychophysiology, KU Leuven Medical School, 3000 Leuven, Belgium, Department of Health Sciences and Technology, ETH Zurich, 8057 Zurich, Switzerland, Department of Experimental Psychology, University of Oxford, OX1 3UD Oxford, United Kingdom.
authors.forename: Dante
authors.identifier: http://orcid.org/0000-0001-6485-5559
authors.initials: D
authors.lastname: Mantini
authors.affiliation: Neurology Department, University Hospitals Leuven, 3000 Leuven, Belgium, Laboratory for Cognitive Neurology, Neurosciences Department, KU Leuven, 3000 Leuven, Belgium.
authors.forename: Rik
authors.identifier: http://orcid.org/0000-0001-6237-2502
authors.initials: R
authors.lastname: Vandenberghe
authors.affiliation: Laboratory for Neuro-and Psychophysiology, KU Leuven Medical School, 3000 Leuven, Belgium, Harvard Medical School, Boston, Massachusetts 02115, and MGH Martinos Center for Biomedical Imaging, Charlestown, Massachusetts 02129 wim@nmr.mgh.harvard.edu.
authors.forename: Wim
authors.identifier: http://orcid.org/0000-0002-9399-343X
authors.initials: W
authors.lastname: Vanduffel
mesh_terms: D000818:Animals; D001288:Attention; D063132:Connectome; D005260:Female; D008253:Macaca mulatta; D008297:Male; D010296:Parietal Lobe / Q000502:physiology*; D013028:Space Perception; D014793:Visual Cortex / Q000502:physiology*
keywords: fMRI; human; monkey; shifting; spatial attention; superior parietal lobe