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 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 ” 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

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) 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:

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