| |
Abstract:
Abstract: Multisensory integrative neurons in superior
colliculi of cat and monkey exhibit marked increases in firing rate
in response to bimodal inputs in spatial correspondence that are
typically greater than the sum of their responses to the individual
components. In contrast, spatially incongruent intersensory inputs
often depress firing rates below the levels expected by summing the
unimodal responses. In a previous fMRI study in humans, we
identified an area in the left STS that displayed similar response
enhancement and depression to semantically congruent and
incongruent audio-visual speech, suggesting a similar principle of
crossmodal binding in man. Here we report a further fMRI study
designed to investigate whether similar rules of integration
generalise to the crossmodal integration of non-speech inputs
(flashing checkerboard and bursts of phase-locked or phase
incoherent white noise) and for the binding of temporal pattern
information. Comparison of unimodal responses with phase-locked or
phase incoherent bimodal inputs revealed a network of brain areas
showing supra-additive and sub-additive signal changes, including
the superior colliculi, insula cortex, left STS and right inferior
parietal lobule. These data suggest that response enhancement and
depression to congruent and incongruent multisensory inputs may be
a defining feature of crossmodal binding that operates at various
levels of human CNS and irrespective of the nature of the
information being combined.
|
