title: Local inhibition shapes duration tuning in the inferior colliculus of guinea pigs.
abstract: Neural tuning to sound durations is a useful filter for the identification of a variety of sounds. Previous studies have shown that the interaction between excitatory and inhibitory inputs plays a role in duration selectivity in echolocating bats. However, this has not been investigated in non-echolocating mammals. In the inferior colliculus (IC) of these mammals, it is recognized that the excitatory responses to sounds are mediated through AMPA and NMDA receptors while the inhibitory input is mediated through gamma-aminobutyric acid (GABA) and glycine receptors. The present study explores the potential interplay between inhibitory and excitatory inputs and its role in the duration selectivity of IC neurons in guinea pigs. It was found that the application of bicuculline (BIC, a GABA A blocker) and/or strychnine (STRY, a glycine blocker) eliminated or reduced duration tuning in most units that were duration tuned (32 out of 39 for BIC, 50 out of 64 for STRY, respectively). The inhibitory input (either by GABA or by glycine) appeared to have a stronger regulating effect on the early excitation mediated by AMPA than on later excitation by NMDA. This is more distinguishable in neurons that show duration selectivity. In conclusion, the inhibitory effect on the early responses appears to be the main contributor for the duration selectivity of the IC in guinea pigs; potential mechanisms for this duration selectivity are also discussed.
authors.affiliation: The Affiliated Sixth People's Hospital, Otolaryngology Institute of Shanghai Jiao Tong University, 600 Yishan Road, 7th Building Rm220, Shanghai 200233, China.
authors.forename: Shankai
authors.initials: S
authors.lastname: Yin
authors.forename: Zhengnong
authors.initials: Z
authors.lastname: Chen
authors.forename: Dongzhen
authors.initials: D
authors.lastname: Yu
authors.forename: Yanmei
authors.initials: Y
authors.lastname: Feng
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
mesh_terms: D000161:Acoustic Stimulation; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001307:Auditory Perception / Q000502:physiology*; D001640:Bicuculline / Q000494:pharmacology*; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology*; D058787:GABA-A Receptor Antagonists; D018684:Glycine Agents / Q000494:pharmacology; D006168:Guinea Pigs; D007245:Inferior Colliculi / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D011963:Receptors, GABA-A / Q000502:physiology; D018009:Receptors, Glycine / Q000037:antagonists & inhibitors / Q000502:physiology; D013331:Strychnine / Q000494:pharmacology; D013997:Time Factors
chemical_list: D018756:GABA Antagonists; D058787:GABA-A Receptor Antagonists; D018684:Glycine Agents; D011963:Receptors, GABA-A; D018009:Receptors, Glycine; D013331:Strychnine; D001640:Bicuculline