title: Synaptic mechanisms shaping delay-tuned combination-sensitivity in the auditory thalamus of mustached bats.
abstract: For the processing of target-distance information, delay-tuned auditory neurons of the mustached bat show facilitative responses to a combination of signal elements of a biosonar pulse-echo pair with a specific echo delay. They are initially produced in the inferior colliculus by facilitative responses based on the coincidence of the rebound response following glycinergic inhibition to the first harmonic of the pulse and a short-latency response to the 2nd-4th harmonics of its echo. Here, we report that further facilitative responses to pulse-echo pairs of thalamic delay-tuned neurons are mediated by glutamate receptors (NMDA and non-NMDA receptors), and that GABAergic inhibition shortens the duration of facilitative responses mediated by NMDA-receptors, without changing the delay tuning of thalamic delay-tuned neurons. Different from collicular delay-tuned neurons, thalamic ones respond much more to pulse-echo pairs than individual signal elements. The neural mechanisms involved in shaping thalamic delay-tuning support a model of hierarchical signal processing in the auditory system.
authors.affiliation: Department of Biology, Washington University, One Brookings Drive, St. Louis, MO 63130, USA. Electronic address: jbutman@nih.gov.
authors.forename: John A
authors.initials: JA
authors.lastname: Butman
authors.affiliation: Department of Biology, Washington University, One Brookings Drive, St. Louis, MO 63130, USA. Electronic address: sugahn@att.net.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Suga
mesh_terms: D000161:Acoustic Stimulation; D000162:Acoustics; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D002685:Chiroptera; D004455:Echolocation / Q000502:physiology; D004566:Electrodes; D005829:Geniculate Bodies / Q000502:physiology; D018698:Glutamic Acid / Q000737:chemistry; D007245:Inferior Colliculi / Q000502:physiology; D007608:Kainic Acid / Q000737:chemistry; D016202:N-Methylaspartate / Q000737:chemistry; D009474:Neurons / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013788:Thalamus / Q000502:physiology*; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000737:chemistry
chemical_list: D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D007608:Kainic Acid
keywords: Echolocation; FM–FM neurons; GABAergic inhibition; Hierarchical processing; NMDAergic facilitation; Non-NMDA-mediated facilitation