Sound localization behavior in ferrets: Comparison of acoustic orientation and approach-to-target responses
- 作者：F.R. Nodal ; V.M. Bajo ; C.H. Parsons ; J.W. Schnupp ; A.J. King
- 关键词：head movement ; orienting response ; auditory space ; azimuth ; mutual information
- 刊名：Neuroscience
- 出版年：2008
- 期刊代码：50_03064522
- 类别：neu
- 出版时间：12 June 2008
- 卷：154
- 期：1
- 页码：397-408
- 文件大小：619 K
摘要
Auditory localization experiments typically either require subjects to judge the location of a sound source from a discrete set of response alternatives or involve measurements of the accuracy of orienting responses made toward the source location. To compare the results obtained by both methods, we trained ferrets by positive conditioning to stand on a platform at the center of a circular arena prior to stimulus presentation and then approach the source of a broadband noise burst delivered from 1 of 12 loudspeakers arranged at 30° intervals in the horizontal plane. Animals were rewarded for making a correct choice. We also obtained a non-categorized measure of localization accuracy by recording head-orienting movements made during the first second following stimulus onset. The accuracy of the approach-to-target responses declined as the stimulus duration was reduced, particularly for lateral and posterior locations, although responses to sounds presented in the frontal region of space and directly behind the animal remained quite accurate. Head movements had a latency of 
direct.com/scidirimg/entities/223c.gif" alt="not, vert, similar" title="not, vert, similar" border="0">200 ms and varied systematically in amplitude with stimulus direction. However, the final head bearing progressively undershot the target with increasing eccentricity and rarely exceeded 60° to each side of the midline. In contrast to the approach-to-target responses, the accuracy of the head orienting responses did not change much with stimulus duration, suggesting that the improvement in percent correct scores with longer stimuli was due, at least in part, to re-sampling of the acoustical stimulus after the initial head turn had been made. Nevertheless, for incorrect trials, head orienting responses were more closely correlated with the direction approached by the animals than with the actual target direction, implying that at least part of the neural circuitry for translating sensory spatial signals into motor commands is shared by these two behaviors.