title: Local neuronal circuits that may shape the discharge patterns of inferior collicular neurons.
abstract: The discharge patterns of neurons in auditory centers encode information about sounds. However, few studies have focused on the synaptic mechanisms underlying the shaping of discharge patterns using intracellular recording techniques. Here, we investigated the discharge patterns of inferior collicular (IC) neurons using intracellular recordings to further elucidate the mechanisms underlying the shaping of discharge patterns. Under in vivo intracellular recording conditions, recordings were obtained from 66 IC neurons in 18 healthy adult mice (Mus musculus, Km) under free field-stimulation. Fifty-eight of these neurons fi red bursts of action potentials (APs) to auditory stimuli and the remaining eight just generated local responses such as excitatory (n = 4) or inhibitory (n = 4) postsynaptic potentials. Based on the APs and subthreshold responses, the discharge patterns were classified into seven types: phasic (24/58, 41.4%), phasic burst (8/58,13.8%), pauser (4/58, 6.9%), phasic-pauser (1/58, 1.7%), chopper (2/58, 3.4%), primary-like tonic (14/58, 24.1%) and sound-induced inhibitory (5/58,8.6%). We concluded that (1) IC neurons exhibit at least seven distinct discharge patterns; (2) inhibition participates in shaping the discharge pattern of most IC neurons and plays a role in sculpting the pattern, except for the primary-like tonic pattern which was not shaped by inhibition; and (3) local neural circuits are the likely structural basis that shapes the discharge patterns of IC neurons and can be formed either in the IC or in lower-level auditory structures.
authors.affiliation: School of Life Sciences & Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, 430079, China.
authors.forename: Zi-Ying
authors.initials: ZY
authors.lastname: Fu
authors.forename: Hui-Xian
authors.initials: HX
authors.lastname: Mei
authors.forename: Liang
authors.initials: L
authors.lastname: Cheng
authors.forename: Jing
authors.initials: J
authors.lastname: Bai
authors.forename: Jia
authors.initials: J
authors.lastname: Tang
authors.forename: Philip Hung-Sun
authors.initials: PH
authors.lastname: Jen
authors.forename: Qi-Cai
authors.initials: QC
authors.lastname: Chen
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001307:Auditory Perception / Q000502:physiology; D007245:Inferior Colliculi / Q000502:physiology*; D051379:Mice; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D009435:Synaptic Transmission / Q000502:physiology*