Miller G L, Knudsen E I
Department of Neurobiology, Stanford University, Stanford, California 94305, USA.
J Neurosci. 1999 Mar 15;19(6):2326-36. doi: 10.1523/JNEUROSCI.19-06-02326.1999.
Auditory spatial information is processed in parallel forebrain and midbrain pathways. Sensory experience early in life has been shown to exert a powerful influence on the representation of auditory space in the midbrain space-processing pathway. The goal of this study was to determine whether early experience also shapes the representation of auditory space in the forebrain. Owls were raised wearing prismatic spectacles that shifted the visual field in the horizontal plane. This manipulation altered the relationship between interaural time differences (ITDs), the principal cue used for azimuthal localization, and locations of auditory stimuli in the visual field. Extracellular recordings were used to characterize ITD tuning in the auditory archistriatum (AAr), a subdivision of the forebrain gaze fields, in normal and prism-reared owls. Prism rearing altered the representation of ITD in the AAr. In prism-reared owls, unit tuning for ITD was shifted in the adaptive direction, according to the direction of the optical displacement imposed by the spectacles. Changes in ITD tuning involved the acquisition of unit responses to adaptive ITD values and, to a lesser extent, the elimination of responses to nonadaptive (previously normal) ITD values. Shifts in ITD tuning in the AAr were similar to shifts in ITD tuning observed in the optic tectum of the same owls. This experience-based adjustment of binaural tuning in the AAr helps to maintain mutual registry between the forebrain and midbrain representations of auditory space and may help to ensure consistent behavioral responses to auditory stimuli.
听觉空间信息在平行的前脑和中脑通路中进行处理。研究表明，生命早期的感觉经验对中脑空间处理通路中听觉空间的表征具有强大影响。本研究的目的是确定早期经验是否也会塑造前脑中听觉空间的表征。猫头鹰在幼年时佩戴棱镜眼镜，该眼镜会在水平面上移动视野。这种操作改变了用于方位定位的主要线索——双耳时间差（ITD）与视野中听觉刺激位置之间的关系。利用细胞外记录来表征正常和经棱镜饲养的猫头鹰前脑凝视区的一个细分区域——听觉原纹状体（AAr）中的ITD调谐情况。棱镜饲养改变了AAr中ITD的表征。在经棱镜饲养的猫头鹰中，根据眼镜所施加的视觉位移方向，ITD的单位调谐向适应方向偏移。ITD调谐的变化包括获得对适应性ITD值的单位反应，以及在较小程度上消除对非适应性（先前正常）ITD值的反应。AAr中ITD调谐的偏移与在同一只猫头鹰的视顶盖中观察到的ITD调谐偏移相似。AAr中基于经验的双耳调谐调整有助于维持前脑和中脑听觉空间表征之间的相互对齐，并可能有助于确保对听觉刺激做出一致的行为反应。
