title: The Insula Mediates Access to Awareness of Visual Stimuli Presented Synchronously to the Heartbeat.
abstract: The processing of interoceptive signals in the insular cortex is thought to underlie self-awareness. However, the influence of interoception on visual awareness and the role of the insular cortex in this process remain unclear. Here, we show in a series of experiments that the relative timing of visual stimuli with respect to the heartbeat modulates visual awareness. We used two masking techniques and show that conscious access for visual stimuli synchronous to participants' heartbeat is suppressed compared with the same stimuli presented asynchronously to their heartbeat. Two independent brain imaging experiments using high-resolution fMRI revealed that the insular cortex was sensitive to both visible and invisible cardio-visual stimulation, showing reduced activation for visual stimuli presented synchronously to the heartbeat. Our results show that interoceptive insular processing affects visual awareness, demonstrating the role of the insula in integrating interoceptive and exteroceptive signals and in the processing of conscious signals beyond self-awareness.
  
  
  
  There is growing evidence that interoceptive signals conveying information regarding the internal state of the body influence perception and self-awareness. The insular cortex, which receives sensory inputs from both interoceptive and exteroceptive sources, is thought to integrate these multimodal signals. This study shows that cardiac interoceptive signals modulate awareness for visual stimuli such that visual stimuli occurring at the cardiac frequency take longer to access visual awareness and are more difficult to discriminate. Two fMRI experiments show that the insular region is sensitive to this cardio-visual synchrony even when the visual stimuli are rendered invisible through interocular masking. The results indicate a perceptual and neural suppression for visual events coinciding with cardiac interoceptive signals.
authors.affiliation: Laboratory of Cognitive Neuroscience and Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Geneva 1202, Switzerland; royesal@gmail.com.
authors.forename: Roy
authors.initials: R
authors.lastname: Salomon
authors.affiliation: Laboratory of Cognitive Neuroscience and Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Geneva 1202, Switzerland;
authors.forename: Roberta
authors.initials: R
authors.lastname: Ronchi
authors.affiliation: Laboratory of Cognitive Neuroscience and Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Geneva 1202, Switzerland;
authors.forename: Jonathan
authors.initials: J
authors.lastname: Dönz
authors.affiliation: Laboratory of Cognitive Neuroscience and Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Geneva 1202, Switzerland;
authors.forename: Javier
authors.initials: J
authors.lastname: Bello-Ruiz
authors.affiliation: Laboratory of Cognitive Neuroscience and Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Geneva 1202, Switzerland;
authors.forename: Bruno
authors.initials: B
authors.lastname: Herbelin
authors.affiliation: Laboratory of Cognitive Neuroscience and Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Geneva 1202, Switzerland;
authors.forename: Remi
authors.initials: R
authors.lastname: Martet
authors.affiliation: Laboratory of Cognitive Neuroscience and Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Geneva 1202, Switzerland;
authors.forename: Nathan
authors.initials: N
authors.lastname: Faivre
authors.affiliation: Neurosurgery Division, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva 1211, Switzerland.
authors.forename: Karl
authors.initials: K
authors.lastname: Schaller
authors.affiliation: Laboratory of Cognitive Neuroscience and Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Geneva 1202, Switzerland; Department of Neurology and.
authors.forename: Olaf
authors.initials: O
authors.lastname: Blanke
mesh_terms: D000293:Adolescent; D000328:Adult; D001364:Awareness; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D006321:Heart / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D065812:Interoception; D008279:Magnetic Resonance Imaging; D008297:Male; D010470:Perceptual Masking; D010775:Photic Stimulation; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult
keywords: continuous flash suppression; high-resolution fMRI; insula; interoception; visual awareness