Auditory oddball responses in Tursiops truncatus

Matt D Schalles,Peter L Tyack,Barbara Shinn-Cunningham,Jason Mulsow,James J Finneran,Dorian S Houser

doi:10.1121/10.0005991

Abstract

Two previous studies suggest that bottlenose dolphins exhibit an "oddball" auditory evoked potential (AEP) to stimulus trains where one of two stimuli has a low probability of occurrence relative to another. However, they reported oddball AEPs at widely different latency ranges (50 vs 500 ms). The present work revisited this experiment in a single dolphin to report the AEPs in response to two tones each assigned probabilities of 0.2, 0.8, and 1 across sessions. The AEP was further isolated from background EEG using independent component analysis, and showed condition effects in the 40-60 ms latency range.

Highlights

Bottlenose dolphins have a remarkable ability to detect and identify underwater objects in complicated acoustic environments based solely on echoic information, and they use passive listening to identify threats, prey, and individual conspecifics (Au, 1993; Harley and DeLong, 2008; Tyack, 1998)
Two previous studies suggest that bottlenose dolphins exhibit an “oddball” auditory evoked potential (AEP) to stimulus trains where one of two stimuli has a low probability of occurrence relative to another
A split half comparison indicated reliability of the AEP component resulting from Independent Component Analysis (ICA) decomposition

Summary

Introduction

Bottlenose dolphins have a remarkable ability to detect and identify underwater objects in complicated acoustic environments based solely on echoic information, and they use passive listening to identify threats, prey, and individual conspecifics (Au, 1993; Harley and DeLong, 2008; Tyack, 1998). A potential means of expanding this subject pool (ideally including free-ranging dolphins) is the further development of non-invasive electrophysiological methods. Neurophysiological auditory brainstem response (ABR) methods over the past 40 years provide a solid foundation for basic auditory processing in dolphins (Mooney et al, 2012; Supin et al, 2001), but they are not well equipped to answer questions about the role of auditory expectancy in passive or active listening tasks. Advances in human research involve wearable EEG devices and spatial filters like Independent Component Analysis (ICA), which could translate to applications for dolphin auditory neuroscience. Studies of auditory expectancy using oddball paradigms have revealed brain responses generally arising from the cortex in humans (Picton, 2011) and other terrestrial mammals (Nelken and Ulanovsky, 2007)

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