Dear Colleagues: The paper below has just been published in JEB: Songhai Li, Paul E. Nachtigall and Marlee Breese. 2011. Dolphin hearing during echolocation: evoked potential responses in an Atlantic bottlenose dolphin (Tursiops truncatus). The Journal of Experimental Biology 214, 2027-2035. doi:10.1242/jeb.053397 SUMMARY Auditory evoked potential (AEP) responses were recorded during echolocation in an Atlantic bottlenose dolphin (Tursiops truncatus) trained to accept suction-cup EEG electrodes and detect targets by echolocation. AEP recording was triggered by the echolocation clicks of the animal. Three targets with target strengths of –34, –28 and –22dB were used at a target distance of 2 to 6.5m for each target. The results demonstrated that the AEP appeared to both outgoing echolocation clicks and echoes during echolocation, with AEP complexes consisting of alternative positive and negative waves. The echo-related AEP amplitudes were obviously lower than the outgoing click-related AEP amplitudes for all the targets at the investigated target distances. However, for targets with target strengths of –22 and –28dB, the peak-to-peak amplitudes of the echo-related AEPs were dependent on the target distances. The echo-related AEP response amplitudes increased at further target distances, demonstrating an overcompensation of echo attenuation with target distance in the echo-perception system of the dolphin biosonar. Measurement and analysis of outgoing click intensities showed that the click levels increased with target distance (R) by a factor of approximately 10 to 17.5logR depending on target strength. The results demonstrated that a dual-component biosonar control system formed by intensity compensation behavior in both the transmission and receiving phases of a biosonar cycle exists synchronously in the dolphin biosonar system. If anybody is interested in getting a pdf copy, please email Dr. Songhai Li at songhai@hawaii.edu Aloha Songhai 2011-05-25 ------------------------------------------------------------- Songhai LI, Ph.D http://www2.hawaii.edu/~songhai/