The Journal of Neuroscience, November 15, 2001, 21(22):8886-8894
Sensory and Multisensory Responses in the Newborn Monkey Superior
Colliculus
Mark T.
Wallace and
Barry E.
Stein
Department of Neurobiology and Anatomy, Wake Forest University
School of Medicine, Winston-Salem, North Carolina 27157
Superior colliculus (SC) neurons have the ability to synthesize
information from different sensory modalities, resulting in enhancements (or depressions) of their activity. This physiological capacity is, in turn, closely tied to changes in overt attentive and
orientation responses. The present study shows that, in contrast to
more altricial species, many deep layer SC neurons in the rhesus monkey
are multisensory at birth. Such neurons can respond to stimuli from
different sensory modalities, and all convergence patterns seen in the
adult are represented. Nevertheless, these neurons cannot yet
synthesize their multisensory inputs. Rather, they respond to
combinations of cross-modal stimuli much like they respond to their
individual modality-specific components. This immature property of
multisensory neurons is in contrast to many of the surprisingly
sophisticated modality-specific response properties of these neurons
and of their modality-specific neighbors. Thus, although deep SC
neurons in the newborn have longer latencies and larger receptive
fields than their adult counterparts, they are already highly active
and are distributed in the typical adult admixture of visual, auditory,
somatosensory, and multisensory neurons. Furthermore, the receptive
fields of these neurons are already ordered into well organized
topographic maps, and the different receptive fields of the same
multisensory neurons show a good degree of cross-modal spatial
register. These data, coupled with those from cat, suggest that the
capacity to synthesize multisensory information does not simply appear
in SC neurons at a prescribed maturational stage but rather develops
only after substantial experience with cross-modal cues.
Key words:
cross-modal; multisensory integration; superior colliculus; sensory development; visual; auditory; somatosensory
Copyright © 2001 Society for Neuroscience 0270-6474/01/21228886-09$05.00/0
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