Show Reference: "Incorporating Cross-Modal Statistics in the Development and Maintenance of Multisensory Integration"

Incorporating Cross-Modal Statistics in the Development and Maintenance of Multisensory Integration The Journal of Neuroscience, Vol. 32, No. 7. (15 February 2012), pp. 2287-2298, doi:10.1523/jneurosci.4304-11.2012 by Jinghong Xu, Liping Yu, Benjamin A. Rowland, Terrence R. Stanford, Barry E. Stein
@article{xu-et-al-2012,
    abstract = {Development of multisensory integration capabilities in superior colliculus ({SC}) neurons was examined in cats whose visual–auditory experience was restricted to a circumscribed period during early life (postnatal day 30–8 months). Animals were periodically exposed to visual and auditory stimuli appearing either randomly in space and time, or always in spatiotemporal concordance. At all other times animals were maintained in darkness. Physiological testing was initiated at ∼2 years of age. Exposure to random visual and auditory stimuli proved insufficient to spur maturation of the ability to integrate cross-modal stimuli, but exposure to spatiotemporally concordant cross-modal stimuli was highly effective. The multisensory integration capabilities of neurons in the latter group resembled those of normal animals and were retained for >16 months in the absence of subsequent visual–auditory experience. Furthermore, the neurons were capable of integrating stimuli having physical properties differing significantly from those in the exposure set. These observations suggest that acquiring the rudiments of multisensory integration requires little more than exposure to consistent relationships between the modality-specific components of a cross-modal event, and that continued experience with such events is not necessary for their maintenance. Apparently, the statistics of cross-modal experience early in life define the spatial and temporal filters that determine whether the components of cross-modal stimuli are to be integrated or treated as independent events, a crucial developmental process that determines the spatial and temporal rules by which cross-modal stimuli are integrated to enhance both sensory salience and the likelihood of eliciting an {SC}-mediated motor response.},
    author = {Xu, Jinghong and Yu, Liping and Rowland, Benjamin A. and Stanford, Terrence R. and Stein, Barry E.},
    day = {15},
    doi = {10.1523/jneurosci.4304-11.2012},
    issn = {1529-2401},
    journal = {The Journal of Neuroscience},
    keywords = {auditory, behaviour, biology, calibration, development, enhancement, inhibition, learning, sc},
    month = feb,
    number = {7},
    pages = {2287--2298},
    pmid = {22396404},
    posted-at = {2012-10-02 11:11:51},
    priority = {2},
    publisher = {Society for Neuroscience},
    title = {Incorporating {Cross-Modal} Statistics in the Development and Maintenance of Multisensory Integration},
    url = {http://dx.doi.org/10.1523/jneurosci.4304-11.2012},
    volume = {32},
    year = {2012}
}

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Xu et al. stress the point that in their cat rearing experiments, multisensory integration arises although there is no reward and no goal-directed behavior connected with the stimuli.

The fact that multi-sensory integration arises without reward connected to stimuli motivates unsupervised learning approaches to SC modeling.

The precise characteristics of multi-sensory integration were shown to be sensitive to their characteristics in the experienced real world during early life.

Xu et al. raised two groups of cats in darkness and presented one with congruent and the other with random visual and auditory stimuli. They showed that SC neurons in cats from the concruent stimulus group developed multi-sensory characteristics while the other mostly did not.

In the experiment by Xu et al., SC neurons in cats that were raised with congruent audio-visual stimuli distinguished between disparate combined stimuli, even if these stimuli were both in the neurons' receptive fields. Xu et al. state that this is different in naturally reared cats.

In the the experiment by Xu et al., SC neurons in cats that were raised with congruent audio-visual stimuli had a preferred time difference between onset of visual and auditory stimuli of 0s whereas this is around 50-100ms in normal cats.

In the the experiment by Xu et al., SC neurons in cats reacted best to auditory and visual stimuli that resembled those they were raised with (small flashing spots, broadband noise bursts), however, they generalized and reacted similarly to other stimuli.

In the study due to Xu et al., multi-sensory enhancement in specially-raised cats decreased gradually with distance between uni-sensory stimuli instead of occurring if and only if stimuli were present in their RFs. This is different from cats that are raised normally in which enhancement occurs regardless of stimulus distance if both uni-sensory components both are within their RF.