Set and setting: How behavioral state regulates sensory function and plasticity

• Effects of three behavioral state features (attention, reinforcement, and vigilance) are described in specific sensory systems.
• Attention decreases discrimination thresholds for attended stimuli, and increases thresholds for non-attended stimuli.
• Various reinforcement parameters and reward cues can be encoded at the level of primary sensory cortices.
• Changes in neuromodulation and network activity during sleep are associated with plasticity in sensory systems.

Recently developed neuroimaging and electrophysiological techniques are allowing us to answer fundamental questions about how behavioral states regulate our perception of the external environment. Studies using these techniques have yielded surprising insights into how sensory processing is affected at the earliest stages by attention and motivation, and how new sensory information received during wakefulness (e.g., during learning) continues to affect sensory brain circuits (leading to plastic changes) during subsequent sleep. This review aims to describe how brain states affect sensory response properties among neurons in primary and secondary sensory cortices, and how this relates to psychophysical detection thresholds and performance on sensory discrimination tasks. This is not intended to serve as a comprehensive overview of all brain states, or all sensory systems, but instead as an illustrative description of how three specific state variables (attention, motivation, and vigilance [i.e., sleep vs. wakefulness]) affect sensory systems in which they have been best studied.