L09. Echolocation in Bats Feedback on written assignments Monday: W10 Neural Circuits Wednesday: W 11 Discussion Revised discussion dates (on web calendar) September 9, 2011 © Carl D. Hopkins Neural circuits feed forward excitation Circuits feedback inhibition + delay-line coincidence detector lateral inhibition reciprocal inhibition Feedforward excitation rhythm generator Echolocation discovery echolocating animals sounds and echoes animals with broad bandwidth sounds animals with narrow bandwidth sounds Stretch Receptor in Crayfish is a “sensory neuron” Excitatory Circuit for Negative Feedback Stim SA RA Membrane channels MSC mechanosensitive Na – sodium K – potassium Cl - chloride Bo Rydqvist, Jia-Hui Lin, Peter Sand, Christer Swerup (2007) Mechanotransduction and the crayfish stretch receptor. Physiol.5 & Behavior. 92: 21-8. 1 3. synapse cell body 4. motor neuron 2. sensory dendrite 1. sensory transduction muscle stimulus 7 Bullock, Orkand, Grinnell (1977) Bullock, Orkand, Grinnell (1977) Bullock, Orkand, Grinnell (1977) b) Delay-line coincidence detector responds to movement direction Feedback Inhibition a b1 b2 b1 b2 null direction preferred direction b1 |||||||| |||||||| |||||| |||||||||| b2 |||||||||| output 2 a) A delay line inhibitory circuit blanks excitation in the null direction Lateral Inhibition enhances spatial contrast b1 b2 null direction preferred direction b1 |||||||| |||||||| |||||| |||||||||| b2 |||||||| output Reciprocal Inhibition with Post- Reciprocal Inhibition Inhibitory Rebound First cell to fire determines the direction of response Echolocation Discovery of Echolocation African megaderm nose leaf bat 3 Discovery of Ultrasound 1) Donald Griffin and George W. Pierce (1938) recorded ultrasound from bats. 2) Measured the approach terminal “buzzes”, measured behavioral accuracy in navigating wire maze. 3) Galambos (1940’s) established ultrasound audition in bats & mice. 4) K. Roeder (1950’s) showed some insects detect ultrasound using electrophysiology. 5) Suga (1970’s-2000): explored neurobiology of bat auditory pathway. 6) James Simmons (1970-80): trained bats to locate “phantom” targets using artificial echoes. Recent literature: correlates between ecology of bat and echolocation performance; much more on neural substrates for echolocation (A mini industry: bat meetings, books, conservation societies, bat Donald R. Griffin houses, bat detectors, sound libraries etc). echolocation: magic well The Nature of Sound Echolocation in Animals Bats (Microchiroptera) Megachiroptera (fruit bats) – only a few species use sonic frequencies (Rousettus). Olibirds (Steatornis caripensis) Cave swiftlett of New Guinea Whales and Dolphins Shrews Catfish Characteristics of Sound Velocity: Intensity: Sound Pressure: Frequency: Bandwidth: Pitch: Waveform: Ultrasound: 4.