Neural correlates of auditory-visual stimulus onset asynchrony detection.
Intersensory temporal synchrony is an ubiquitous sensory attribute that has proven to be critical for binding multisensory inputs, sometimes erroneously leading to dramatic perceptual illusions. However, little is known about how the brain detects temporal synchrony between multimodal sensory inputs. We used positron emission tomography to demonstrate that detecting auditory-visual stimulus onset asynchrony activates a large-scale neural network of insular, posterior parietal, prefrontal, and cerebellar areas with the highest and task-specific activity localized to the right insula. Interregional covariance analysis further showed significant task-related functional interactions between the insula, the posterior thalamus, and superior colliculus. Based on these results and the available electrophysiological and anatomical connectivity data in animals, we propose that the insula, via its known short-latency connections with the tectal system, mediates temporally defined auditory-visual interaction at an early stage of cortical processing permitting phenomena such as the ventriloquist and the McGurk illusions.
Bushara
K O
KO
National Institute of Neurological Disorders and Stroke, Human Motor Control Section, and Cognitive Neuroscience Section, National Institutes of Health, Bethesda, Maryland 20892-1428, USA.
Grafman
J
J
Hallett
M
M
D000161:Acoustic Stimulation; D000328:Adult; D001519:Behavior / Q000502:physiology; D001931:Brain Mapping; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000502:physiology; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D006801:Humans; D007088:Illusions / Q000502:physiology; D007089:Image Enhancement; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000000981:diagnostic imaging / Q000502:physiology; D010296:Parietal Lobe / Q000000981:diagnostic imaging / Q000502:physiology; D010775:Photic Stimulation; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging / Q000502:physiology; D011859:Radiography; D011930:Reaction Time / Q000502:physiology*; D013477:Superior Colliculi / Q000000981:diagnostic imaging / Q000502:physiology; D013788:Thalamus / Q000000981:diagnostic imaging / Q000502:physiology; D014055:Tomography, Emission-Computed