Show Reference: "Development of multisensory integration from the perspective of the individual neuron"

Development of multisensory integration from the perspective of the individual neuron Nature Reviews Neuroscience, Vol. 15, No. 8. (August 2014), pp. 520-535, doi:10.1038/nrn3742 by Barry E. Stein, Terrence R. Stanford, Benjamin A. Rowland
@article{stein-et-al-2014,
    author = {Stein, Barry E. and Stanford, Terrence R. and Rowland, Benjamin A.},
    citeulike-article-id = {13268907},
    citeulike-linkout-0 = {http://dx.doi.org/10.1038/nrn3742},
    citeulike-linkout-1 = {http://dx.doi.org/10.1038/nrn3742},
    doi = {10.1038/nrn3742},
    journal = {Nature Reviews Neuroscience},
    keywords = {biology, development, multisensory-integration, sc},
    month = aug,
    number = {8},
    pages = {520--535},
    posted-at = {2014-07-18 12:56:08},
    priority = {2},
    publisher = {Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.},
    title = {Development of multisensory integration from the perspective of the individual neuron},
    url = {http://dx.doi.org/10.1038/nrn3742},
    volume = {15},
    year = {2014}
}

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Cats, if raised in an environment in which the spatio-temporal relationship of audio-visual stimuli is artificially different from natural conditions, develop spatio-temporal integration of audio-visual stimuli accordingly. Their SC neurons develop preference to audio-visual stimuli with the kind of spatio-temporal relationship encountered in the environment in which they were raised.

Deactivating regions in AES or lateral suprasylvian cortex responsive to some modality can completely eliminate responses of deep SC neurons to that modality.

Very few perceptions are truly affected only by sensation through one sensory modality.

First systematic studies of neural multisensory integration started in the 1970ies.

The SC is involved in generating gaze shifts and other orienting behaviors.

The SC localizes events.

The uni-sensory, multi-sensory and motor maps of the superior colliculus are in spatial register.

Cats, being an altricial species, are born with little to no capability of multi-sensory integration and develop first multi-sensory SC neurons, then neurons exhibiting multi-sensory integration on the neural level only after birth.

In the development of SC neurons, receptive fields are initially very large and shrink with experience.

SC receives tactile localization-related inputs from the trigeminal nucleus.

Multisensory experience is necessary to develop normal multisensory integration.

SC receives auditory localization-related inputs from the IC.

Multisensory integration is a way to reduce uncertainty. This is both a normative argument and it states the evolutionary advantage of using multisensory integration.

Multisensory integration develops after birth in many ways.

Stein offers an operational definition of multisensory integration as

``...the process by which stimuli from different senses combine ... to produce a response that differs from those produced by the component stimuli individually.''

(Some) SC neurons in the newborn cat are sensitive to tactile stimuli at birth, to auditory stimuli a few days postnatally, and to visual stimuli last.

Some animals are born with deep-SC neurons responsive to more than one modality.

However, these neurons don't integrate according to Stein's single-neuron definition of multisensory integration. This kind of multisensory integration develops with experience with cross-modal stimuli.

The most important cortical input to the SC (in cats) comes from layer V cortical neurons from a number of sub-regions of the anterior ectosylvian sulcus (AES):

  • anterior ectosylvian visual area (AEV)
  • the auditory field of AES (FAES)
  • and the fourth somatosensory area (SIV)

These populations in themselves are uni-sensory.

Neural responses in the sc to spatially and temporally coincident cross-sensory stimuli can be much stronger than responses to uni-sensory stimuli.

In fact, they can be much greater than the sum of the responses to either stimulus alone.

One reason for specifically studying multi-sensory integration in the (cat) SC is that there is a well-understood connection between input stimuli and overt behavior.

Stein defines multi-sensory integration on the single-neuron level as

``a statistically significant difference between the number of impulses evoked by a cross-modal combination of stimuli and the number evoked by the most effective of these stimuli individually.''

Multisensory integration is present in neonates to some degree depending on species (more in precocial than in altricial species), but it is subject to postnatal development and then influenced by experience.

Neurons in the superficial SC are almost exclusively visual in most species.