Effects of motor denervation of the external ear muscles on the audio-visual targeting reflex in cats.

The effect of uni- and bilateral denervation of muscles of the pinna on the audio-visual targeting reflex reinforced by food was studied. In comparison with the normal group the unilaterally denervated animals showed a decreased capacity to localize sound sources placed behind the animal ipsi- and contralaterally to the operated side. The denervation of the second ear in these animals induced a further decrease of the localization scores, especially of the sources placed behind them. The localization behavior strategies were different depending on the integrity of the innervation of muscles of the pinna. The stimulation of the operated side with tones of a 30 dB higher intensity than in the normal side did not improve the animals’performance in localizing the sound sources. The shortening of duration from 500 to 50 ms reduced, the capacity to localize the loudspeakers placed ipsilaterally to the denervated side, especially those behind the animal. The role for the targeting reflex of the feedback information from the muscles controlling the pinna movements, and the significance of the postural changes induced by the tone are discussed.