Temporal-Coherence Induces Binding of Responses to Sound Sequences in Ferret Auditory Cortex

Abstract

Binding the attributes of a sensory source is necessary to perceive it as a unified entity, one that can be attended to and extracted from its surrounding scene. In auditory perception, this is the essence of the cocktail party problem in which a listener segregates one speaker from a mixture of voices, or a musical stream from simultaneous others. It is postulated that coherence of the temporal modulations of a source's features is necessary to bind them. The focus of this study is on the role of temporal-coherence in binding and segregation, and specifically as evidenced by the neural correlates of rapid plasticity that enhance cortical responses among synchronized neurons, while suppressing them among asynchronized ones. In a first experiment, we find that attention to a sound sequence rapidly binds it to other coherent sequences while suppressing nearby incoherent sequences, thus enhancing the contrast between the two. In a second experiment, a sequence of synchronized multi-tone complexes (figure), embedded in a cloud of randomly dispersed desynchronized tones (ground), perceptually and neurally pops-out after a fraction of a second highlighting the binding among its coherent tones against the incoherent background. These findings demonstrate the role of temporal-coherence in binding and segregation.