Wilkinson L K, Meredith M A, Stein B E
Department of Psychology, Virginia Commonwealth University, Richmond 23298, USA.
Exp Brain Res. 1996 Nov;112(1):1-10. doi: 10.1007/BF00227172.
Physiological and behavioral studies in cat have shown that corticotectal influences play important roles in the information-processing capabilities of superior colliculus (SC) neurons. While corticotectal inputs from the anterior ectosylvian sulcus (AES) play a comparatively small role in the unimodal responses of SC neurons, they are particularly important in rendering these neurons capable of integrating information from different sensory modalities (e.g., visual and auditory). The present experiments examined the behavioral consequences of depriving SC neurons of AES inputs, and thereby compromising their ability to integrate visual and auditory information. Selective deactivation of a variety of other cortical areas (posterolateral lateral suprasylvian cortex, PLLS; primary auditory cortex, AI; or primary visual cortex, 17/18) served as controls. Cats were trained in a perimetry device to ignore a brief, low-intensity auditory stimulus but to orient toward and approach a nearthreshold visual stimulus (a light-emitting diode, LED) to obtain food. The LED was presented at different eccentricities either alone (unimodal) or combined with the auditory stimulus (multisensory). Subsequent deactivation of the AES, with focal injections of a local anesthetic, had no effect on responses to unimodal cues regardless of their location. However, it profoundly, though reversibly, altered orientation and approach to multisensory stimuli in contralateral space. The characteristic enhancement of these responses observed when an auditory cue was presented in spatial correspondence with the visual stimulus was significantly degraded. Similarly, the inhibitory effect of a spatially disparate auditory cue was significantly ameliorated. The observed effects were specific to AES deactivation, as similar effects were not obtained with deactivation of PLLS, AI or 17/18, or saline injections into the AES. These observations are consistent with postulates that specific cortical-midbrain interactions are essential for the synthesis of multisensory information in the SC, and for the orientation and localization behaviors that depend on this synthesis.
对猫的生理和行为研究表明，皮质顶盖影响在中脑上丘（SC）神经元的信息处理能力中起着重要作用。虽然来自外侧沟前沟（AES）的皮质顶盖输入在SC神经元的单峰反应中作用相对较小，但它们在使这些神经元能够整合来自不同感觉模态（如视觉和听觉）的信息方面尤为重要。本实验研究了剥夺SC神经元的AES输入的行为后果，从而损害其整合视觉和听觉信息的能力。选择性失活其他各种皮质区域（后外侧上薛氏回皮质，PLLS；初级听觉皮质，AI；或初级视觉皮质，17/18）作为对照。在视野计装置中训练猫忽略短暂的低强度听觉刺激，但朝向并接近近阈值视觉刺激（发光二极管，LED）以获取食物。LED单独（单峰）或以不同离心率呈现，或与听觉刺激（多感觉）组合呈现。随后通过局部注射局部麻醉剂使AES失活，无论单峰线索位于何处，对其反应均无影响。然而，它深刻但可逆地改变了对侧空间中对多感觉刺激的定向和接近。当听觉线索与视觉刺激在空间上对应呈现时观察到的这些反应的特征性增强显著降低。同样，空间上不同的听觉线索的抑制作用也显著减弱。观察到的效应是AES失活所特有的，因为失活PLLS、AI或17/18，或向AES注射生理盐水未获得类似效应。这些观察结果与以下假设一致，即特定的皮质 - 中脑相互作用对于SC中多感觉信息的合成以及依赖于这种合成的定向和定位行为至关重要。
