title: Imbalance of excitation and inhibition at threshold level in the auditory cortex.
abstract: The interplay of cortical excitation and inhibition is a fundamental feature of cortical information processing. Excitation and inhibition in single cortical neurons are balanced in their response to optimal sensory stimulation due to thalamocortical feedforward microcircuitry. It is unclear whether the balance between cortical excitation and inhibition is maintained at the threshold stimulus level. Using in vivo whole-cell patch-clamp recording of thalamocortical recipient neurons in the primary auditory cortex of mice, we examined the tone-evoked excitatory and inhibitory postsynaptic currents at threshold levels. Similar to previous reports, tone induced excitatory postsynaptic currents when the membrane potentials were held at 70 mV and inhibitory postsynaptic currents when the membrane potentials were held at 0 mV on single cortical neurons. This coupled excitation and inhibition is not demonstrated when threshold-level tone stimuli are presented. In most cases, tone induced only excitatory postsynaptic current. The best frequencies of excitatory and inhibitory responses were often different and thresholds of inhibitory responses were mostly higher than those of excitatory responses. Our data suggest that the excitatory and inhibitory inputs to single cortical neurons are imbalanced at the threshold level. This imbalance may result from the inherent dynamics of thalamocortical feedforward microcircuitry.
authors: Department of Physiology, School of Basic Medical Science, Southern Medical University Guangzhou, China ; Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada.
authors: Yan
authors: Y
authors: Zhao
authors: Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada.
authors: Zizhen
authors: Z
authors: Zhang
authors: Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada.
authors: Xiuping
authors: X
authors: Liu
authors: Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada.
authors: Colin
authors: C
authors: Xiong
authors: Department of Physiology, School of Basic Medical Science, Southern Medical University Guangzhou, China.
authors: Zhongju
authors: Z
authors: Xiao
authors: Department of Physiology and Pharmacology, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary Calgary, AB, Canada.
authors: Jun
authors: J
authors: Yan
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D053444:Inhibitory Postsynaptic Potentials / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D009433:Neural Inhibition / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques
keywords: auditory cortex; excitatory-inhibitory imbalance; in vivo whole cell patch; minimal threshold; thalamocortical model