Surprising Twist on Auditory Representation. Focus on: “What's That Sound? Auditory Area CLM Encodes Stimulus Surprise, Not Intensity or Intensity Changes”

Abstract

The concept of sensory representation is central to psychological theories of perception and cognition and to neurobiological models of sensory coding. Understanding exactly what a neural response “represents,” however, turns out to be a difficult question to answer fully—particularly for neurons many synapses away from the point of sensory transduction. A recent paper by Gill and colleagues (2007) takes a large step forward in understanding stimulus representation in the auditory system. To appreciate the contribution this paper makes, it’s helpful to have a little background. To a first approximation, sensory systems and the receptive fields they comprise are organized hierarchically. The concept of a “receptive field” was first applied to the visual system (Hartline 1938) to describe the sensitivity of optic nerve fibers to light shined on spatially restricted portions of the retina. While neurons in primary visual cortex inherit the spatial receptive fields of the retinal projections, they respond to oriented bars or edges rather than spots of light. At higher levels in the visual pathway, cells respond best to complex