Neural basis of multisensory looming signals

• Published in: NeuroImage (Orlando, Fla.) Vol. 65; pp. 13 - 22
• Main Authors: Tyll, Sascha, Bonath, Björn, Schoenfeld, Mircea Ariel, Heinze, Hans-Jochen, Ohl, Frank W., Noesselt, Tömme
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 15.01.2013; Elsevier; Elsevier Limited
• Subjects: Acoustic Stimulation; Adult; Audiovisual looming; Auditory Perception - physiology; Biological and medical sciences; Brain; Brain - physiology; Brain Mapping; Comprehension - physiology; Connectivity; Cortex (auditory); Female; fMRI; Fundamental and applied biological sciences. Psychology; Human; Humans; Magnetic Resonance Imaging; Male; Multisensory integration; Photic Stimulation; Reaction Time - physiology; Studies; Vertebrates: nervous system and sense organs; Visual Perception - physiology; Young Adult; Human; Audiovisual looming; fMRI; Connectivity; Multisensory integration; Nuclear magnetic resonance imaging; Functional imaging
• ISSN: 1053-8119; 1095-9572
• DOI: 10.1016/j.neuroimage.2012.09.056

Approaching or looming signals are often related to extremely relevant environmental events (e.g. threats or collisions) making these signals critical for survival. However, the neural network underlying multisensory looming processing is not yet fully understood. Using functional magnetic resonance imaging (fMRI) we identified the neural correlates of audiovisual looming processing in humans: audiovisual looming (vs. receding) signals enhance fMRI-responses in low-level visual and auditory areas plus multisensory cortex (superior temporal sulcus; plus parietal and frontal structures). When characterizing the fMRI-response profiles for multisensory looming stimuli, we found significant enhancements relative to the mean and maximum of unisensory responses in looming-sensitive visual and auditory cortex plus STS. Superadditive enhancements were observed in visual cortex. Subject-specific region-of-interest analyses further revealed superadditive response profiles within all sensory-specific looming-sensitive structures plus bilateral STS for audiovisual looming vs. summed unisensory looming conditions. Finally, we observed enhanced connectivity of bilateral STS with low-level visual areas in the context of looming processing. This enhanced coupling of STS with unisensory regions might potentially serve to enhance the salience of unisensory stimulus features and is accompanied by superadditive fMRI-responses. We suggest that this preference in neural signaling for looming stimuli effectively informs animals to avoid potential threats or collisions. ► The ability to discern approaching from receding events is critical for survival. ► Approaching (Looming) stimuli selectively enhance perceptual sensitivity. ► We examine the neural underpinnings of audiovisual looming signals in humans. ► Looming signals activate a network of sensory-specific and multisensory brain areas. ► Enhanced connectivity between regions might enhance the salience of stimuli features.