Evoked Potentials in the Central Auditory System of Alert Porpoises to Their Own and Artificial Sounds
A series of 8 experiments is reported in which arrays of 7 or more electrodes on an axis were implanted stereotaxically in Tursiops truncatus. From 1 to 3 of the electrodes were in or near the inferior colliculus or lateral lemniscus.
A total of 39 electrodes out of 130 proved to be responsive to suitable acoustic stimuli. Nine of these lay above the tentorium, 30 in the midbrain above the ventral tegmentum.
The typical midbrain evoked potential is specialized for ultrasonic, ultrabrief, fast rising, closely spaced sounds like the echolocating clicks. It has a short latency and the main deflection is less than 1 ms wide. No potential is evoked if the frequency is below 5 kHz or the rise time above 5 ms.
At several cerebral loci a different response was found: long latency, long duration, slowly recovering potentials evoked by frequencies below 5 kHz whether fast or slowly rising. The cerebral “whistle” sensitive loci are probably in the posterolateral temporal cortex.
A few loci at about the tentorial level, probably rostral and lateral to the inferior colliculus gave intermediate or mixed response with some features of each of the previous 2 types.
Implanted, cooperating porpoises were trained to give series of clicks of echolocating types. These evoked potentials like those to artificial tone bursts. Often the highest intensity voluntary clicks evoked quite modest potentials and a much weaker form of click gave maximal potentials. Important differences in click composition are inferred.
Artificial echoes show more rapid recovery following the porpoise’s own click than following an artificial conditioning tone burst of equal evoking power.
It has proven practicable to place electrodes with reasonable accuracy, to combine computerized electrophysiological analysis with trained behavior and to maintain chronic implants for at least a month in porpoises. Opportunities for improvements in technique are emphasized.
KeywordsAuditory System Inferior Colliculus Bottlenose Dolphin Recording Session Acoustic Pulse
Unable to display preview. Download preview PDF.
- Anderson, S. (1970). Auditory sensitivity of the harbour porpoise, Phocoena phocoena. In: Investigations on Cetacea, Vol. 2., Pilleri, G. (Ed.) Brain Anatomy Institute, University of Berne, Switzerland.Google Scholar
- Biederman-Thorson, A. (1969). Personal communication.Google Scholar
- Breathnach, A. S. (1960.) The cetacean central nervous system. Biol. Rev. (Cambridge), 35 (2) 187–230.Google Scholar
- Bullock, T. H., Grinnell, A. D., Ikezono, E., Kameda, K., Katsuki, K., Nomoto, M., Sato, O., Suga, N., and Yanagisawa, K. (1968). Electrophysiological studies of central auditory mechanisms in cetaceans. Z. uergl. Physiol., 59: 117–156.Google Scholar
- Bullock, T. H. and Ridgway, S. H. (1971). Neurophysiological findings relevant to echolocation in marine animals. In: Orientation and Navigation in Animals. Schmidt-Koenig, K. and Thompson, M. F. (Eds.), American Institute of Biological Sciences, Washington, D. C.Google Scholar
- Bullock, T. H., Ridgway, S. H., and Suga, N. (1971). Acoustically evoked potentials in midbrain auditory structures in sea lions (Pinnipedia). Z. vergl. Physiol. (In press.)Google Scholar
- Caldwell, M. C., Caldwell, D. K., and Turner, R. H. (1970). Statistical analysis of the signature whistle of an Atlantic bottlenose dolphin with correlations between vocal changes and level of arousal. Los Angeles Co., Calif. Museum of Natural History, Los Angeles, Foundation. Technical Report. A0708687. Doc 1 L870192 T255 No. 8.Google Scholar
- Evans, W. E. (1970). Personal communication.Google Scholar
- Evans, W. E. and Powell, B. A. (1966). Discrimination of different metallic plates. by an echolocating delphinid. In: Animal Sonar Systems, Biology and Bionics Busnel, R. G. (Ed.) Evans, W. E. and Powell, B. A 78, France.Google Scholar
- Grinnell, A. D. (1963a). The neurophysiology of audition in bats: intensity and frequency parameters. J. Physiol., 167: 38–66.Google Scholar
- Grinnell, A. D. (1963b). The neurophysiology of audition in bats: temporal parameters. J. Physiol., 167: 67–96.Google Scholar
- Henson, O. W. (1966). The perception and analysis of biosonar signals by bats. In: Animal Sonar Systems, Biology and Bionics, Busnel, R. G. (Ed.) Henson, O. W 78, France.Google Scholar
- Jansen, J. and Jansen, J. K. S. (1969). The nervous system of Cetacea. In: The Biology of Marine Mammals. Andersen, H. T. (Ed.) Academic Press, New York and London, pp. 175-252.Google Scholar
- Kellogg, W. N. (1961). Porpoises and Sonar. University of Chicago Press, Chicago. Kitahata, L. M., Amakata, Y. and Galambos, R. (1969). Effects of halothane upon auditory recovery functions in cats. J. Pharmac. Exp. Ther., 167: 14–25.Google Scholar
- Kruger, L. (1966). Specialized features of the cetacean brain. In: Whales, Dolphins and Porpoises. Norris, K. S. (Ed.) University of California Press, Berkeley.Google Scholar
- Lilly. J. C. (1962). Man and Dolphin. Pyramid Publications, New York.Google Scholar
- Lilly, J. C. (1963). Modern whales, dolphins and porpoises, as challenges to our intelligence. In: The Dolphin in History, Montagu, A. and Lilly, J. C. (Eds.) Clark Memorial Library, University of California Press, Los Angeles.Google Scholar
- Lilly, J. C. (1965). Sonic-ultrasonic emissions of the bottlenose dolphin. In: Whales, Dolphins, and Porpoises. Norris, K. S. (Ed.) University of California Press, Berkeley.Google Scholar
- Lilly, J. C. (1967). The Mind of the Dolphin: A Nonhuman Intelligence. Doubleday, Garden City and New York.Google Scholar
- Lilly, J. C. (1967). Dolphin vocalization. In: Brain Mechanisms Underlying Speech and Language. Grune and Stratton, New York.Google Scholar
- Mccormick, J. G., Wever, E. G., Ridgway, S. H., and Palin, J. (1969). Physiology of hearing in odontocetes as indicated by their cochlear potentials. Proc. Acous. Soc. Amer., 78: 20.Google Scholar
- Norris, K. S. (1966). Whales, Dolphins and Porpoises. University of California Press, Berkeley.Google Scholar
- Norris, K. S., Evans, W. E. and Turner, R. N. (1966). Echolocation in an Atlantic bottlenose porpoise during discrimination. Animal Sonar Systems, Biology and Bionics. Busnel, R. G. (Ed.) Laboratoire de Physiologie Acoustique,Jouy-en-Josas 78,France.Google Scholar
- Piddington, R. W. (1971). Discrimination between acoustic compressions and rarefactions by goldfish. J. Exp. Biol. (In press.).Google Scholar
- Pilleri, G. (1970). Investigations on Cetacea. Brain Anatomy Institute, University of Berne, Switzerland.Google Scholar
- Riese, W. (1927). Über den Bau und die Leistungen des akustischen Systems der Wale. J. Psychol. Neurol., 34: 194–201.Google Scholar