Yee K K, Costanzo R M
Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0551, USA.
Physiol Behav. 1995 Nov;58(5):959-68. doi: 10.1016/0031-9384(95)00159-g.
Transection of olfactory nerve fibers leads to deafferentation of olfactory bulbs and a loss of olfactory mediated behavior. Nerve transection studies have shown that during recovery, olfactory nerve fibers can reestablish connections with the olfactory bulbs. Two groups of experimental animals were studied to determine if olfactory mediated behavior returns after recovery. One group (n = 18) received bilateral olfactory nerve transection (BTX), while the second group (n = 4) received a sham surgical procedure. Performance on odor detection and discrimination tasks was measured during recovery periods ranging from 1-120 days. Return of olfactory mediated behavior was first observed 19 days after nerve transection. Performance levels improved with recovery time and by day 40 animals returned to criterion level (> or = 90% correct response). Sham animals maintained a criterion level of performance throughout the recovery period. Horseradish peroxidase (HRP) was used to trace reconnection of olfactory nerve fibers. The absence of HRP label in the bulbs of animals examined one day after BTX, verified the completeness of the nerve transection procedure. After 10 days of recovery, a few HRP labeled axons were observed and the amount of HRP in the bulb increased with recovery time. The results of this study demonstrate that olfactory receptor axons can reestablish functional connections with the deafferented olfactory bulb and these connections are sufficient to restore olfactory mediated behavior.
嗅神经纤维横断会导致嗅球传入神经阻滞及嗅觉介导行为丧失。神经横断研究表明，在恢复过程中，嗅神经纤维可与嗅球重新建立联系。本研究对两组实验动物进行了研究，以确定恢复后嗅觉介导行为是否会恢复。一组（n = 18）接受双侧嗅神经横断（BTX），而第二组（n = 4）接受假手术。在1至120天的恢复期间测量气味检测和辨别任务的表现。嗅觉介导行为在神经横断后19天首次观察到恢复。表现水平随恢复时间而提高，到第40天时动物恢复到标准水平（正确反应≥90%）。假手术动物在整个恢复期间保持标准表现水平。用辣根过氧化物酶（HRP）追踪嗅神经纤维的重新连接。BTX后一天检查的动物嗅球中无HRP标记，证实了神经横断手术的完整性。恢复10天后，观察到一些HRP标记的轴突，且嗅球中HRP的量随恢复时间增加。本研究结果表明，嗅觉受体轴突可与去传入神经的嗅球重新建立功能连接，且这些连接足以恢复嗅觉介导行为。
