title: Invariance of evoked-potential echo-responses to target strength and distance in an echolocating false killer whale.
abstract: Brain auditory evoked potentials (AEPs) 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 strength varied from -22 to -40 dB; the distance varied from 1.5 to 6 m. All the records contained two AEP sets: the first one of a constant latency (transmission-related AEP) and a second one with a delay proportional to the distance (echo-related AEP). The amplitude of echo-related AEPs was almost independent of both target strength and distance, though combined variation of these two parameters resulted in echo intensity variation within a range of 42 dB. The amplitude of transmission-related AEPs was independent of distance but dependent on target strength: the less the target strength, the higher the amplitude. Recording of transmitted pulses has not shown their intensity dependence on target strength. It is supposed that the constancy of echo-related AEP results from variation of hearing sensitivity depending on the target strength and release of echo-related responses from masking by transmitted pulses depending on the distance.
authors: Institute of Ecology and Evolution of the Russian Academy of Sciences, 33 Leninsky Prospect, 119071 Moscow, Russia. alex_supin@sevin.ru
authors: Alexander Ya
authors: AY
authors: Supin
authors: Paul E
authors: PE
authors: Nachtigall
authors: Whitlow W L
authors: WW
authors: Au
authors: Marlee
authors: M
authors: Breese
mesh_terms: D000818:Animals; D001288:Attention / Q000502:physiology; D002540:Cerebral Cortex / Q000502:physiology; D004215:Distance Perception / Q000502:physiology*; D004289:Dolphins / Q000502:physiology*; D004455:Echolocation / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D011571:Psychoacoustics; D013018:Sound Spectrography