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Unformatted text preview: Problems with polygenic traits Temperature coupling experiments grasshoppers (Bauer and von Helverson, 87) polythermic female parts: feature detector is in the head of the female crickets (Pires and Hoy, 92) plurisegmental phonotactic preference IV. Feature Detectors in Predator/Prey interactions a. b. c. e.g. echolocation in bats (Donald Griffin) avoidance by moths moth ears on thorax NEURAL MECHANISMS FOR IDENTIFYING A KEY STIMULUS
2. FEATURE DETECTOR EXAMPLE 1 1 d. hear only in ultrasonic range; tuned to bats V. MOTIVATION FEATURE DETECTOR FIXED ACTION PATTERN
1) FIND A VISUAL TARGET 2) TURN TO FACE PREY TOAD FLY DETECTOR 3) SHOOT OUT TONGUE 4) RETRACT TONGUE 5) CLOSE EYES 6) SWALLOWS 7) WIPES MOUTH Toads use feature detectors That are built into their eyes & central nervous system Lateral Inhibition = Mutual inhibition between neighboring cells in a sensory system In the visual system, this enhances edges and thus improves shape detection 2 SENSITIVITY TO WORM-LIKE OBJECTS worm anti-worm what matters:
the elongation of the object in relation to its direction of movement. Responses of neurons from optic tectum Tectal class T5(2) neurons SUMMARY
Lateral inhibition -> Shape Tectal class T5(2) neurons -> direction MAIN POINT
simple, innately recognized visual sign stimuli are generally extracted by feature detectors. 3 SENSORY...
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- Spring '09