Multisensory Networks in Primary and Association Cortices in Cat
Our perceptual view of the world is made up of stimuli from multiple sensory modalities. The brain is well-equipped to synthesize incoming sensory information in order to create appropriate percepts of the world and initiate adaptive behaviors. Unique external events can frequently be described by more than one sensory cue and the central nervous system is tasked to properly integrate (or segregate) these sensory signals, which often leads to a variety of perceptual and behavioral benefits. These benefits are the result of circuit computations in a complex and distributed network of brain regions. Elucidating the neural substrates of multisensory processing in the context of network activity has just begun. The cat is an excellent model to investigate response patterns of neural assemblies and to identify multisensory processing strategies across different brain regions. Regions of the cerebral cortex designated as both primary and associational show multisensory interactions, which manifest as changes in response magnitude and response onset. These interactions are dependent on stimulus factors such as spatial location, timing, and relative effectiveness, which are all strongly interrelated. Analysis across cortical layers revealed that multisensory interactions are a result of inputs from both thalamus and other cortical regions, suggesting a complex interplay between feedforward and feedback mechanisms.