Neuronal mechanisms, response dynamics and perceptual functions of multisensory interactions in auditory cortex

Musacchia, Gabriella; Schroeder, Charles E.

doi:10.1016/j.heares.2009.06.018

Cited by 94 publications

(70 citation statements)

References 87 publications

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“…Early multisensory interactions are occurring simultaneously in this distributed network of regions. This synchronicity is consistent with extrapolation of timing data available from monkeys (Musacchia and Schroeder, 2009), wherein the timing of multisensory effects would be largely constrained by the arrival of visually driven inputs. That is, auditory responses in all of the regions where we observed nonlinear interactions could begin before the arrival of visual responses.…”

Section: Discussionsupporting

confidence: 84%

Auditory–Visual Multisensory Interactions in Humans: Timing, Topography, Directionality, and Sources

Cappe¹,

Thut²,

Romei³

et al. 2010

J. Neurosci.

133

117

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Current models of brain organization include multisensory interactions at early processing stages and within low-level, including primary, cortices. Embracing this model with regard to auditory-visual (AV) interactions in humans remains problematic. Controversy surrounds the application of an additive model to the analysis of event-related potentials (ERPs), and conventional ERP analysis methods have yielded discordant latencies of effects and permitted limited neurophysiologic interpretability. While hemodynamic imaging and transcranial magnetic stimulation studies provide general support for the above model, the precise timing, superadditive/subadditive directionality, topographic stability, and sources remain unresolved. We recorded ERPs in humans to attended, but task-irrelevant stimuli that did not require an overt motor response, thereby circumventing paradigmatic caveats. We applied novel ERP signal analysis methods to provide details concerning the likely bases of AV interactions. First, nonlinear interactions occur at 60 -95 ms after stimulus and are the consequence of topographic, rather than pure strength, modulations in the ERP. AV stimuli engage distinct configurations of intracranial generators, rather than simply modulating the amplitude of unisensory responses. Second, source estimations (and statistical analyses thereof) identified primary visual, primary auditory, and posterior superior temporal regions as mediating these effects. Finally, scalar values of current densities in all of these regions exhibited functionally coupled, subadditive nonlinear effects, a pattern increasingly consistent with the mounting evidence in nonhuman primates. In these ways, we demonstrate how neurophysiologic bases of multisensory interactions can be noninvasively identified in humans, allowing for a synthesis across imaging methods on the one hand and species on the other.

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Section: Discussionsupporting

confidence: 84%

Auditory–Visual Multisensory Interactions in Humans: Timing, Topography, Directionality, and Sources

Cappe¹,

Thut²,

Romei³

et al. 2010

J. Neurosci.

133

117

View full text Add to dashboard Cite

show abstract

“…Primate studies indicate that multisensory interactions between hearing and touch occur in the auditory cortex of hearing individuals (Kayser et al, 2005), with some very early somatosensory responses to median nerve electrical stimulation in primary auditory cortex (Lakatos et al, 2007). In addition, visual stimuli influence auditory cortex (Bizley et al, 2007;Kayser et al, 2007), and multisensory interactions occur in low-level auditory cortex (Musacchia and Schroeder, 2009). In our study, even the hearing participants had increased signal in Heschl's gyrus and superior-temporal cortex for bimodal stimuli relative to unimodal stimuli.…”

Section: Discussionmentioning

confidence: 99%

Altered Cross-Modal Processing in the Primary Auditory Cortex of Congenitally Deaf Adults: A Visual-Somatosensory fMRI Study with a Double-Flash Illusion

Karns¹,

Dow²,

Neville³

2012

Journal of Neuroscience

167

152

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The developing brain responds to the environment by using statistical correlations in input to guide functional and structural changesthat is, the brain displays neuroplasticity. Experience shapes brain development throughout life, but neuroplasticity is variable from one brain system to another. How does the early loss of a sensory modality affect this complex process? We examined cross-modal neuroplasticity in anatomically defined subregions of Heschl's gyrus, the site of human primary auditory cortex, in congenitally deaf humans by measuring the fMRI signal change in response to spatially coregistered visual, somatosensory, and bimodal stimuli. In the deaf Heschl's gyrus, signal change was greater for somatosensory and bimodal stimuli than that of hearing participants. Visual responses in Heschl's gyrus, larger in deaf than hearing, were smaller than those elicited by somatosensory stimulation. In contrast to Heschl's gyrus, in the superior-temporal cortex visual signal was comparable to somatosensory signal. In addition, deaf adults perceived bimodal stimuli differently; in contrast to hearing adults, they were susceptible to a double-flash visual illusion induced by two touches to the face. Somatosensory and bimodal signal change in rostrolateral Heschl's gyrus predicted the strength of the visual illusion in the deaf adults in line with the interpretation that the illusion is a functional consequence of the altered cross-modal organization observed in deaf auditory cortex. Our results demonstrate that congenital and profound deafness alters how vision and somatosensation are processed in primary auditory cortex.

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“…In marmosets, retrograde tracers in A1 also did not produce labeled cells in early visual areas (Cappe and Barone 2005), but the ferret does have a projection from V1 to A1 (Bizley et al 2007). At least some visual responses have been identified in A1 (Kayser et al 2007(Kayser et al , 2008, but these could arise from other sources besides early visual cortex, for example, from thalamic nuclei or multisensory association areas (Musacchia and Schroeder 2009;Smiley and Falchier 2009). …”

Section: Reciprocity Of Visuo-auditory Convergence Pathwaysmentioning

confidence: 95%

Projection from Visual Areas V2 and Prostriata to Caudal Auditory Cortex in the Monkey

et al. 2009

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Studies in humans and monkeys report widespread multisensory interactions at or near primary visual and auditory areas of neocortex. The range and scale of these effects has prompted increased interest in interconnectivity between the putatively ''unisensory'' cortices at lower hierarchical levels. Recent anatomical tract-tracing studies have revealed direct projections from auditory cortex to primary visual area (V1) and secondary visual area (V2) that could serve as a substrate for auditory influences over low-level visual processing. To better understand the significance of these connections, we looked for reciprocal projections from visual cortex to caudal auditory cortical areas in macaque monkeys. We found direct projections from area prostriata and the peripheral visual representations of area V2. Projections were more abundant after injections of temporoparietal area and caudal parabelt than after injections of caudal medial belt and the contiguous areas near the fundus of the lateral sulcus. Only one injection was confined to primary auditory cortex (area A1) and did not demonstrate visual connections. The projections from visual areas originated mainly from infragranular layers, suggestive of a ''feedback''-type projection. The selective localization of these connections to peripheral visual areas and caudal auditory cortex suggests that they are involved in spatial localization.

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Neuronal mechanisms, response dynamics and perceptual functions of multisensory interactions in auditory cortex

Cited by 94 publications

References 87 publications

Auditory–Visual Multisensory Interactions in Humans: Timing, Topography, Directionality, and Sources

Auditory–Visual Multisensory Interactions in Humans: Timing, Topography, Directionality, and Sources

Altered Cross-Modal Processing in the Primary Auditory Cortex of Congenitally Deaf Adults: A Visual-Somatosensory fMRI Study with a Double-Flash Illusion

Projection from Visual Areas V2 and Prostriata to Caudal Auditory Cortex in the Monkey

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