Early Experiments Discover Lateralization
Lateral dominance of the hypoglossal nerve conveying messages from the brain to the syrinx was first observed in the 1970s. This lateral dominance was determined in a breed of canary, the waterschlager canary, bred for its long and complex song, by lesioning the ipsilateral tracheosyringeal branch of the hypoglossal nerve, disabling either the left or right syrinx. The numbers of song elements in the birds’ repertoires were greatly attenuated when the left side was cut, but only modestly attenuated when the right side was disabled, indicating left syringeal dominance of song production in these canaries. Similar lateralized effects have been observed in other species such as the white-crowned sparrow (Zonotrichia leucophrys), the Java sparrow (Lonchura oryzivora) and the zebra finch (Taeniopygia guttata), which is right-side dominant. However, denervation in these birds does not entirely silence the affected syllables but creates qualitative changes in phonology and frequency.
Read more about this topic: Lateralization Of Bird Song
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