Transformation of acoustic information to sensory decisions in parietal cortex

Abstract

Integrating sensory information over time is fundamental for guiding perceptual decisions. This process is facilitated by the transformation of stimulus representations downstream of sensory cortex. Here, we ask how the neural representations of auditory information are transformed in the auditory-recipient parietal cortex, a region that is causally associated with sound-driven perceptual decisions. Wireless recordings of neural activity were conducted in parietal cortex while gerbils performed an alternative forced-choice (AFC) auditory temporal integration task. Gerbils were required to discriminate amplitude modulated (AM) noise at 4 vs 10 Hz across various signal durations (100–2000 ms). Task performance was poor at short AM durations (100–300 ms), improved with longer durations, and reached an optimum at ≥600 ms. During task performance, individual neurons displayed a rise in firing rate that peaked prior to the animals’ decision. Population activity from simultaneously recorded parietal cortex neurons was strongly correlated with behavior outcomes, leaving open whether parietal representation was purely motor-related or included a sensory component. Thus, we evaluated population activity during disengaged sessions, and found a representation of the acoustic stimulus. Our findings suggest that parietal cortex neurons represent both the acoustic stimulus and sound-driven decision, demonstrating the progression of auditory processing downstream of auditory cortex.