Development of Multisensory Processing in Ferret Parietal Cortex.
Abstract
It is well known that the nervous system adjusts itself to its
environment during development. Although a great deal of effort has been
directed toward understanding the developmental processes of the
individual sensory systems (e.g., vision, hearing, etc.), only one major
study has examined the maturation of multisensory processing of cortical
neurons. Therefore, the present investigation sought to evaluate
multisensory development in a different cortical region and species.
Using multiple single-unit recordings in anesthetized ferrets (n=18) of
different ages (from postnatal day 80 through 300), we studied the
responses of neurons from the rostral posterior parietal area (PPr) to
presentations of visual, tactile and combined visual-tactile
stimulation. The results showed that multisensory neurons were
infrequent at the youngest ages (pre-pubertal) and progressively
increased through the later ages. Significant response changes that
result from multisensory stimulation (defined as multisensory
integration, MSI) were observed in post-pubertal adolescent animals and
the magnitude of these integrated responses also increased across this
age group. Furthermore, non-significant multisensory response changes
were progressively increased in adolescent animals. Collectively, at the
population level, MSI was observed to shift from primarily suppressive
levels in infants to increasingly higher levels in later stages. These
data indicate that, like the unisensory systems from which it is
derived, multisensory processing shows developmental changes the
specific time course of which may be regionally and species dependent.