title: The interaction of outgoing echolocation pulses and echoes in the false killer whale's auditory system: evoked-potential study.
abstract: Brain auditory evoked potentials (AEP) associated with echolocation were recorded in a false killer whale Pseudorca crassidens trained to accept suction-cup EEG electrodes and to detect targets by echolocation. AEP collection was triggered by echolocation pulses transmitted by the animal. The target was a hollow aluminum cylinder of strength of -22 dB at a distance from 1 to 8 m. Each AEP record was obtained by averaging more than 1000 individual records. All the records contained two AEP sets: the first one of a constant latency and a second one with a delay proportional to the distance. The timing of these two AEP sets was interpreted as responses to the transmitted echolocation pulse and echo, respectively. The echo-related AEP, although slightly smaller, was comparable to the outgoing click-related AEP in amplitude, even though at a target distance as far as 8 m the echo intensity was as low as -64 dB relative to the transmitted pulse in front of the head. The amplitude of the echo-related AEP was almost independent of distance, even though variation of target distance from 1 to 8 m influenced the echo intensity by as much as 36 dB.
authors.affiliation: Institute of Ecology and Evolution, Russian Academy of Sciences, 33 Leninsky Prospect, 119071 Moscow, Russia. alex_supin@sevin.ru
authors.forename: Alexander Ya
authors.initials: AY
authors.lastname: Supin
authors.forename: Paul E
authors.initials: PE
authors.lastname: Nachtigall
authors.forename: Whitlow W L
authors.initials: WW
authors.lastname: Au
authors.forename: Marlee
authors.initials: M
authors.lastname: Breese
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001300:Audiometry, Evoked Response / Q000379:methods; D004193:Discrimination Learning / Q000502:physiology; D004289:Dolphins / Q000502:physiology*; D004455:Echolocation / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D005556:Form Perception / Q000502:physiology