title: Encoding of natural sounds by variance of the cortical local field potential.
abstract: Neural encoding of sensory stimuli is typically studied by averaging neural signals across repetitions of the same stimulus. However, recent work has suggested that the variance of neural activity across repeated trials can also depend on sensory inputs. Here we characterize how intertrial variance of the local field potential (LFP) in primary auditory cortex of awake ferrets is affected by continuous natural sound stimuli. We find that natural sounds often suppress the intertrial variance of low-frequency LFP (<16 Hz). However, the amount of the variance reduction is not significantly correlated with the amplitude of the mean response at the same recording site. Moreover, the variance changes occur with longer latency than the mean response. Although the dynamics of the mean response and intertrial variance differ, spectro-temporal receptive field analysis reveals that changes in LFP variance have frequency tuning similar to multiunit activity at the same recording site, suggesting a local origin for changes in LFP variance. In summary, the spectral tuning of LFP intertrial variance and the absence of a correlation with the amplitude of the mean evoked LFP suggest substantial heterogeneity in the interaction between spontaneous and stimulus-driven activity across local neural populations in auditory cortex.
authors.affiliation: College of Biomedical Engineering and Instrument Sciences, Zhejiang University, Zhejiang, China; ding_nai@zju.edu.cn.
authors.forename: Nai
authors.initials: N
authors.lastname: Ding
authors.affiliation: Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland; Department of Biology, University of Maryland, College Park, Maryland; Institute for Systems Research, University of Maryland, College Park, Maryland; and.
authors.forename: Jonathan Z
authors.initials: JZ
authors.lastname: Simon
authors.affiliation: Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland; Institute for Systems Research, University of Maryland, College Park, Maryland; and.
authors.forename: Shihab A
authors.initials: SA
authors.lastname: Shamma
authors.affiliation: Oregon Hearing Research Center, Oregon Health and Science University, Portland, Oregon.
authors.forename: Stephen V
authors.initials: SV
authors.lastname: David
mesh_terms: D000818:Animals; D001303:Auditory Cortex / Q000166:cytology / Q000502:physiology*; D001307:Auditory Perception; D005072:Evoked Potentials, Auditory; D005289:Ferrets; D009474:Neurons / Q000502:physiology; D011930:Reaction Time; D013016:Sound
keywords: auditory cortex; local field potential; response variance; spectro-temporal receptive field; speech