BIOL 306 Lecture Notes - Lecture 29: Frequency Analysis, White Spot, Sensory System
15 Jan 2018
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Sharks sense signals even though they"re receiving much stronger signals from elsewhere e. g. from their own muscle activity. Looking at electroreceptor afferent fiber: record how they fire when there"s nothing happening except the skate ventillating (i. e. moving gills) Firing rate of afferent fiber is modulated by movement. Fires in the rhythm of the ventilation movement. It"s really hard to detect response to weak electrical stimulus in activity. Looking at next level of processing: at baseline condition, when there"s no external stimulus, the 2nd order neurons don"t do anything, don"t respond to ventilation input, cancels it out. Adding weak external stimulus weak stimulus gets through. Second order neuron detects weak stimulus even when there"s another strong self-generated stimulus. Predictable information/input = reafferent (caused by the fish"s own activity) = suppressed at the level of second-order neurons. Bodznick et al. (2009): recorded second-order neuron that ignores sensory input that is consistently associated with ventilation.
