Multisensory integration: current issues from the perspective of the single neuron

• Published in: Nature reviews. Neuroscience Vol. 9; no. 4; pp. 255 - 266
• Main Authors: Stein, Barry E, Stanford, Terrence R
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.04.2008; Nature Publishing Group
• Subjects: Afferent Pathways - physiology; Animal Genetics and Genomics; Animals; Behavioral Sciences; Biological and medical sciences; Biological Techniques; Biomedical and Life Sciences; Biomedicine; Brain; Brain Mapping; Central nervous system; Cerebral Cortex - cytology; Electrophysiology; Fundamental and applied biological sciences. Psychology; General aspects. Models. Methods; Humans; Mental Processes - physiology; Neural circuitry; Neurobiology; Neurons; Neurons - physiology; Neurosciences; Physiological aspects; Physiology; review-article; Sensation - physiology; Senses; Sensory stimulation; Vertebrates: nervous system and sense organs; United States; Ability; Vertebrata; Cerebral cortex; Experience; Mammalia; Neuron; Central nervous system; Midbrain; Multisensory integration; Review; Encephalon
• ISSN: 1471-003X; 1471-0048; 1469-3178
• DOI: 10.1038/nrn2331

Key Points Having information from multiple senses converge onto the same neurons allows the neurons to work in concert so that their combined product can enhance the physiological salience of an event, increase the ability to render a judgment about its identity, and initiate responses faster than would otherwise be possible. This interactive synergy among the senses, or 'multisensory integration', is manifested in individual neurons, by enhancing or degrading their responses, and in behaviour, by producing corresponding alterations in performance. Multisensory integration is guided by principles that relate to the spatial and temporal relationship among cross-modal stimuli, as well as to the vigor of the neuron's responses to their individual component stimuli. The spatial principle of multisensory integration relies on faithful register among a neuron's different receptive fields and this register must be maintained in spite of independent movement of the sense organs (such as the eyes). Recent studies suggest that compensation for such movement is less than perfect, and occurs to varying degrees in different neurons and brain regions. Degradation in receptive-field register has strong implications for multisensory integration, but these remain to be examined empirically. Multisensory integration is crucial for high-level cognitive functions in which considerations such as semantic congruence might determine its neural products and the perceptions and behaviours that depend on them. Multiple approaches have demonstrated the impact of multisensory integration in different brain structures in different species, including single-neuron and event-related-potential recordings and brain-imaging techniques. Primary, sensory-specific areas of the brain have now been shown to receive inputs from other senses. The functional role of these other inputs is not yet known, but they might facilitate the processing of information in the native sense. Multisensory integration allows information from multiple senses to be combined, with benefits for nervous-system processing. Stein and Stanford discuss the principles of multisensory integration in single neurons in the CNS and consider the questions that the field must address. For thousands of years science philosophers have been impressed by how effectively the senses work together to enhance the salience of biologically meaningful events. However, they really had no idea how this was accomplished. Recent insights into the underlying physiological mechanisms reveal that, in at least one circuit, this ability depends on an intimate dialogue among neurons at multiple levels of the neuraxis; this dialogue cannot take place until long after birth and might require a specific kind of experience. Understanding the acquisition and usage of multisensory integration in the midbrain and cerebral cortex of mammals has been aided by a multiplicity of approaches. Here we examine some of the fundamental advances that have been made and some of the challenging questions that remain.