BASC_201_-_Lecture_13_(Feb_14_-_Dr._Krahe) - Dr. Krahe 13...

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Thursday, February 14, 2008 (BASC 201: Lecture 13) Dr. Krahe Prepared by Elizabeth Penttila 133 February 14, 2008 – Dr. Krahe
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Thursday, February 14, 2008 (BASC 201: Lecture 13) Dr. Krahe Prepared by Elizabeth Penttila *Note : THIS IS AN UNEDITED VERSION OF THE NTC. The NTC is currently under review by the editor, and so the edited version will be posted shortly . Dr. Krahe is a professor of Neurobiology; students who enjoy this lecture might consider taking BIOL 306: Neurobiology. Professor Krahe’s Research -Focused on the brain’s extraction of behaviorally relevant material from the continuous stream of input received from the sensory organs. - Speech, for example, is the extraction of meaning from utterances. - Prey detection and examination from the environment. -Special interest in the evolution of these and other mechanisms of communication. - Subjects of his research include Grasshoppers (covered extensively in BIOL 306), Bats, Moths with ultrasonic genital communication, and electric fish. Electric Fish - First described by C.W. Coates. - Continue to serve as a design system for neurotransmitters (due in large part to their unusual use of electric currents). - Capable of discharging up to 600 volts! (Strongly electric fish) - Weakly electric fish, however, produce fields not tangible to most creatures. They have an odd physical makeup that includes a belly fin on an otherwise eel-like body. They are nocturnal and reside mostly in shallow, murky water. Species in South America and Africa are very similar, probably as a result of convergent evolution. - The electrical organs of the fish produce a field potential, as shown in this diagram. By rapidly switching from head-positive-tail-negative to head-negative- tail-positive (up to 1,000/sec or 1,000 Hz) a frequency is produced over the given field. o Objects near the fish perturb this current, and the electric receptors throughout the fish’s body relay this information to the brain, creating a spatial map. This allows the fish to move with confidence in its dark, murky habitat. o
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This note was uploaded on 04/29/2008 for the course BASC 201 taught by Professor Lefebvre during the Winter '08 term at McGill.

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BASC_201_-_Lecture_13_(Feb_14_-_Dr._Krahe) - Dr. Krahe 13...

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