Goulet S, Doré F Y, Murray E A
Ecole de Psychologie, Université Laval, Quebec, Canada.
Exp Brain Res. 1998 Mar;119(2):131-40. doi: 10.1007/s002210050326.
In macaque monkeys, aspiration but not excitotoxic lesions of the medial temporal lobe limbic structures, the amygdala and hippocampus, produce a severe impairment in visual recognition memory. Furthermore, certain ventromedial cortical regions, namely the rhinal (i.e., entorhinal and perirhinal) cortex, are now known to be critical for visual recognition memory. Because the route taken by temporal cortical efferent fibers, especially perirhinal efferents, passes nearby the amygdala, it is possible that inadvertent damage to these fibers is produced by the aspirative but not the excitotoxic process, thereby accounting at least in part for the different behavioral outcomes of the two types of lesion. To test this idea, we assessed the integrity of the rhinal corticothalamic projection system after aspiration lesions of the amygdala. Three rhesus monkeys with unilateral amygdala removals received bilaterally symmetrical injections of a retrograde fluorescent tracer into the medial portion of the mediodorsal nucleus of the thalamus. Retrogradely labeled cells were identified using conventional fluorescence microscopy techniques. In all three cases, the rhinal cortex of the intact hemispheres contained moderate numbers of retrogradely labeled cells. By contrast, the rhinal cortex of the amygdalectomized hemispheres consistently contained few retrogradely labeled cells, and a direct comparison of the two hemispheres showed this difference to be statistically significant. A similar asymmetric pattern was observed for area TE but not for the cortex lining the dorsal bank of the superior temporal sulcus, nor for the rostral cingulate motor area, which was examined as a control. The results indicate that aspiration lesions of the amygdala not only remove the cell bodies of the amygdala, as intended, but also inadvertently disrupt projection fibers arising from cells in the rhinal cortex and area TE that pass nearby or through the amygdala en route to the thalamus. Behavioral studies examining the effects of aspiration lesions of the amygdala in nonhuman primates need to take these findings into consideration.
在猕猴中，内侧颞叶边缘结构（杏仁核和海马体）的抽吸性损伤而非兴奋性毒性损伤会导致视觉识别记忆严重受损。此外，现在已知某些腹内侧皮质区域，即鼻周皮质（即内嗅皮质和鼻周皮质），对视觉识别记忆至关重要。由于颞叶皮质传出纤维，尤其是鼻周皮质传出纤维所走的路径靠近杏仁核，所以有可能抽吸性而非兴奋性毒性过程会意外损伤这些纤维，从而至少部分解释了两种损伤类型不同的行为结果。为了验证这一想法，我们评估了杏仁核抽吸性损伤后鼻周皮质丘脑投射系统的完整性。三只单侧杏仁核切除的恒河猴在双侧对称地向丘脑背内侧核的内侧部分注射了逆行荧光示踪剂。使用传统荧光显微镜技术鉴定逆行标记的细胞。在所有三个病例中，完整半球的鼻周皮质含有中等数量的逆行标记细胞。相比之下，杏仁核切除半球的鼻周皮质始终含有很少的逆行标记细胞，对两个半球的直接比较显示这种差异具有统计学意义。对于颞下回（TE）区域观察到了类似的不对称模式，但对于颞上沟背侧缘的皮质以及作为对照检查的喙扣带运动区则未观察到。结果表明，杏仁核的抽吸性损伤不仅如预期那样移除了杏仁核的细胞体，还意外破坏了来自鼻周皮质和TE区域细胞的投射纤维，这些纤维在通往丘脑的途中经过或穿过杏仁核。研究杏仁核抽吸性损伤对非人类灵长类动物影响的行为学研究需要考虑这些发现。
