Auditory motion-specific mechanisms in the primate brain

This work examined the mechanisms underlying auditory motion processing in the auditory cortex of awake monkeys using functional magnetic resonance imaging (fMRI). We tested to what extent auditory motion analysis can be explained by the linear combination of static spatial mechanisms, spectrotemporal processes, and their interaction. We found that the posterior auditory cortex, including A1 and the surrounding caudal belt and parabelt, is involved in auditory motion analysis. Static spatial and spectrotemporal processes were able to fully explain motion-induced activation in most parts of the auditory cortex, including A1, but not in circumscribed regions of the posterior belt and parabelt cortex. We show that in these regions motion-specific processes contribute to the activation, providing the first demonstration that auditory motion is not simply deduced from changes in static spatial location. These results demonstrate that parallel mechanisms for motion and static spatial analysis coexist within the auditory dorsal stream.
Author summary Motion is a fundamental dimension of acoustic and visual stimuli that is critical for animals to interact with their environment. Yet, surprisingly, we still do not understand the basic mechanisms in the brain that underlie perception of auditory motion. For the last 30 y, this research field has been hampered by unsuccessful attempts to answer a simple but fundamental question: is auditory motion perception deduced from processing individual static sounds, or are there mechanisms in the auditory domain dedicated to detecting motion? Here we report the discovery of specific motion detectors located in the auditory cortex of primates. We demonstrate that these auditory motion detectors are close to the well-known visual motion detectors. Both types of detectors are likely to be crucial for the planning of limb and eye movement. This study addresses a fundamental issue in neuroscience and sheds new light on the brain mechanisms underlying the essential aspects of our ability to navigate the world.