title: FM signals produce robust paradoxical latency shifts in the bat's inferior colliculus.
abstract: Previous studies in echolocating bats, Myotis lucifugus, showed that paradoxical latency shift (PLS) is essential for neural computation of target range and that a number of neurons in the inferior colliculus (IC) exhibit unit-specific PLS (characterized by longer first-spike latency at higher sound levels) in response to tone pulses at the unit's best frequency. The present study investigated whether or not frequency-modulated (FM) pulses that mimic the bat's echolocation sonar signals were equally effective in eliciting PLS. For two-thirds of PLS neurons in the IC, both FM and tone pulses could elicit PLS, but only FM pulses consistently produced unit-specific PLS. For the remainder of PLS neurons, only FM pulses effectively elicited PLS; these cells showed either no PLS or no response, to tone pulses. PLS neurons generally showed more pronounced PLS in response to narrow-band FM (each sweeping 20 kHz in 2 ms) pulse that contained the unit's best frequency. In addition, almost all PLS neurons showed duration-independent PLS to FM pulses, but the same units exhibited duration-dependent PLS to tone pulses. Taken together, when compared to tone pulses, FM stimuli can provide more reliable estimates of target range.
authors.affiliation: Department of Molecular and Integrative Physiology and Beckman Institute, University of Illinois, Urbana, IL, 61801, USA. xmwwang@uiuc.edu
authors.forename: Xinming
authors.initials: X
authors.lastname: Wang
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Galazyuk
authors.forename: Albert S
authors.initials: AS
authors.lastname: Feng
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000818:Animals; D001309:Auditory Threshold / Q000502:physiology; D002685:Chiroptera / Q000502:physiology*; D004455:Echolocation / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D007245:Inferior Colliculi / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D011930:Reaction Time / Q000502:physiology*; D013017:Sound Localization / Q000502:physiology*; D013018:Sound Spectrography; D013028:Space Perception / Q000502:physiology