title: Synaptic mechanisms for generating temporal diversity of auditory representation in the dorsal cochlear nucleus.
abstract: In central auditory pathways, neurons exhibit a great diversity of temporal discharge patterns, which may contribute to the parallel processing of auditory signals. How such response diversity emerges in the central auditory circuits remains unclear. Here, we investigated whether synaptic mechanisms can contribute to the generation of the temporal response diversity at the first stage along the central auditory neuraxis. By in vivo whole-cell voltage-clamp recording in the dorsal cochlear nucleus of rats, we revealed excitatory and inhibitory synaptic inputs underlying three different firing patterns of fusiform/pyramidal neurons in response to auditory stimuli: "primary-like," "pauser," and "buildup" patterns. We found that primary-like neurons received strong, fast-rising excitation, whereas pauser and buildup neurons received accumulating excitation with a relatively weak fast-rising phase, followed by a slow-rising phase. Pauser neurons received stronger fast-rising excitation than buildup cells. On the other hand, inhibitory inputs to the three types of cells exhibited similar temporal patterns, all with a strong fast-rising phase. Dynamic-clamp recordings demonstrated that the differential temporal patterns of excitation could primarily account for the different discharge patterns. In addition, discharge pattern in a single neuron varied in a stimulus-dependent manner, which could be attributed to the modulation of excitation/inhibition balance by different stimuli. Further examination of excitatory inputs to vertical/tuberculoventral and cartwheel cells suggested that fast-rising and accumulating excitation might be conveyed by auditory nerve and parallel fibers, respectively. A differential summation of excitatory inputs from the two sources may thus contribute to the generation of response diversity.
authors.affiliation: Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California; Graduate Programs, University of Southern California, Los Angeles, California; and.
authors.forename: Mu
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California; Graduate Programs, University of Southern California, Los Angeles, California; and.
authors.forename: Ya-Tang
authors.initials: YT
authors.lastname: Li
authors.affiliation: Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California; Department of Otolaryngology of Southwest Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Yuan
authors.affiliation: Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California; Department of Cell and Neurobiology, University of Southern California, Los Angeles, California;
authors.forename: Huizhong W
authors.initials: HW
authors.lastname: Tao
authors.affiliation: Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California; Department of Physiology and Biophysics, University of Southern California, Los Angeles, California; liizhang@usc.edu.
authors.forename: Li I
authors.initials: LI
authors.lastname: Zhang
mesh_terms: D000200:Action Potentials; D000818:Animals; D001307:Auditory Perception; D017626:Cochlear Nucleus / Q000166:cytology / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials; D005260:Female; D053444:Inhibitory Postsynaptic Potentials; D009474:Neurons / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time
keywords: central auditory pathway; excitatory/inhibitory balance; in vivo whole-cell recording; synaptic input; voltage clamp