Abstract
The brain faces the difficult task of maintaining a stable representation of key features of the outside world in noisy sensory surroundings. How does the sensory representation change with noise, and how does the brain make sense of it? We investigated the effect of background white noise (WN) on tuning properties of neurons in mouse A1 and its impact on discrimination performance in a go/no-go task. We find that WN suppresses the activity of A1 neurons, which surprisingly increases the discriminability of tones spectrally close to each other. To confirm the involvement of A1, we optogenetically excited parvalbumin-positive (PV+) neurons in A1, which have similar effects as WN on both tuning properties and frequency discrimination. A population model suggests that the suppression of A1 tuning curves increases frequency selectivity and thereby improves discrimination. Our findings demonstrate that the cortical representation of pure tones adapts during noise to improve sensory acuity.
Highlights
Sensory processing is the basis of our interaction with the world and an essential part of brain function
Auditory tuning curves are not, static; they have been shown to adapt during changes in stimulus context (Atiani et al, 2009; Reig et al, 2015) or attentional state (Carcea et al, 2017; Francis et al, 2018; Fritz et al, 2003), and it is believed that this flexibility is relevant for adjusting the dynamic range of sensory representation (Rabinowitz et al, 2013)
white noise (WN) Suppresses Responses to Pure Frequency Tones in A1 To investigate the stability of the representation of key features of an auditory stimulation in the presence of noise, we started by characterizing neural responses to pure frequency tones, perturbed it with a WN background, and determined whether this modification had any consequences at the behavioral level
Summary
Sensory processing is the basis of our interaction with the world and an essential part of brain function. The cochlea deconstructs the external sound environment into frequency components (Von Bekesy, 1960), which are passed further along the auditory pathway up to the primary auditory cortex in a segregated manner (Guo et al, 2012; Hackett et al, 2011). This spatial separation of frequency components, conserved from the cochlea to the primary auditory cortex, is referred to as tonotopy (Evans et al, 1965; Goldstein et al, 1970). Tonotopy translates into spatially organized neurons with frequency-selective receptive fields In many cases, these receptive fields are well characterized by a bell-shaped response to a varying stimulus, referred to as a tuning curve. Auditory tuning curves are not, static; they have been shown to adapt during changes in stimulus context (Atiani et al, 2009; Reig et al, 2015) or attentional state (Carcea et al, 2017; Francis et al, 2018; Fritz et al, 2003), and it is believed that this flexibility is relevant for adjusting the dynamic range of sensory representation (Rabinowitz et al, 2013)
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