Location-specific neural facilitation in marmoset auditory cortex.

A large body of literature has shown that sensory neurons typically exhibit adaptation to repetitive stimulation. However, adaptation alone does not account for the ability of sensory systems to remain vigilant to the environment in spite of repetitive sensory stimulation. Here, we investigated single neuron responses to sequences of sounds repeatedly delivered from a particular spatial location. Instead of inducing adaptation, repetitive stimulation evoked long-lasting and location-specific facilitation (LSF) in firing rate of nearly 90% of recorded neurons. The LSF decreased with decreasing presentation probability and diminished when sounds were randomly delivered from multiple spatial locations. Intracellular recordings showed that repetitive sound stimulation evoked sustained membrane potential depolarization. Computational modeling showed that increased arousal, not decreased inhibition, underlies the LSF. Our findings reveal a novel form of contextual modulation in the marmoset auditory cortex that may play a role in tasks such as auditory streaming and the cocktail party effect.