title: Evidence for a Causal Contribution of Macaque Vestibular, But Not Intraparietal, Cortex to Heading Perception.
abstract: Multisensory convergence of visual and vestibular signals has been observed within a network of cortical areas involved in representing heading. Vestibular-dominant heading tuning has been found in the macaque parietoinsular vestibular cortex (PIVC) and the adjacent visual posterior sylvian (VPS) area, whereas relatively balanced visual/vestibular tuning was encountered in the ventral intraparietal (VIP) area and visual-dominant tuning was found in the dorsal medial superior temporal (MSTd) area. Although the respective functional roles of these areas remain unclear, perceptual deficits in heading discrimination following reversible chemical inactivation of area MSTd area suggested that areas with vestibular-dominant heading tuning also contribute to behavior. To explore the roles of other areas in heading perception, muscimol injections were used to reversibly inactivate either the PIVC or the VIP area bilaterally in macaques. Inactivation of the anterior PIVC increased psychophysical thresholds when heading judgments were based on either optic flow or vestibular cues, although effects were stronger for vestibular stimuli. All behavioral deficits recovered within 36 h. Visual deficits were larger following inactivation of the posterior portion of the PIVC, likely because these injections encroached upon the VPS area, which contains neurons with optic flow tuning (unlike the PIVC). In contrast, VIP inactivation led to no behavioral deficits, despite the fact that VIP neurons show much stronger choice-related activity than MSTd neurons. These results suggest that the VIP area either provides a parallel and partially redundant pathway for this task, or does not participate in heading discrimination. In contrast, the PIVC/VPS area, along with the MSTd area, make causal contributions to heading perception based on either vestibular or visual signals.
  
  
  CONCLUSIONS
  Multisensory vestibular and visual signals are found in multiple cortical areas, but their causal contribution to self-motion perception has been previously tested only in the dorsal medial superior temporal (MSTd) area. In these experiments, we show that inactivation of the parietoinsular vestibular cortex (PIVC) also results in causal deficits during heading discrimination for both visual and vestibular cues. In contrast, ventral intraparietal (VIP) area inactivation led to no behavioral deficits, despite the fact that VIP neurons show much stronger choice-related activity than MSTd or PIVC neurons. These results demonstrate that choice-related activity does not always imply a causal role in sensory perception.
authors.affiliation: Key Laboratory of Brain Functional Genomics (Ministry of Education & Science and Technology Commission of Shanghai Municipality), School of Life Sciences, East China Normal University, Shanghai 200062, China.
authors.forename: Aihua
authors.initials: A
authors.lastname: Chen
authors.affiliation: Institute of Neuroscience, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Gu
authors.affiliation: Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030.
authors.forename: Sheng
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Brain and Cognitive Sciences, Center for Visual Science, University of Rochester, Rochester, New York 14627, and.
authors.forename: Gregory C
authors.identifier: http://orcid.org/0000-0002-1635-1273
authors.initials: GC
authors.lastname: DeAngelis
authors.affiliation: Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030 angelaki@bcm.edu.
authors.forename: Dora E
authors.initials: DE
authors.lastname: Angelaki
mesh_terms: D000818:Animals; D001931:Brain Mapping; D003463:Cues; D004192:Discrimination, Psychological; D007839:Functional Laterality / Q000187:drug effects; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D019416:Head Movements / Q000187:drug effects / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D009039:Motion Perception / Q000187:drug effects / Q000502:physiology*; D009118:Muscimol / Q000494:pharmacology; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology; D057849:Optic Flow / Q000502:physiology*; D010296:Parietal Lobe / Q000187:drug effects / Q000502:physiology*; D010775:Photic Stimulation; D011594:Psychometrics; D011601:Psychophysics; D013702:Temporal Lobe / Q000187:drug effects / Q000502:physiology*
chemical_list: D058785:GABA-A Receptor Agonists; D009118:Muscimol
keywords: PIVC; VIP; heading perception; optic flow; reversible chemical inactivation; vestibular