Shetty Pranav, Shoykhet Michael, Simons Daniel J
Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA.
Somatosens Mot Res. 2003;20(3-4):233-8. doi: 10.1080/08990220310001622951.
Whisker plucking in developing and adult rats provides a convenient method of temporarily altering tactile input for the purposes of studying experience-dependent plasticity in the somatosensory cortex. Yet, a comprehensive examination of the effect of whisker plucking on the response properties of whisker follicle-innervating trigeminal ganglion (NVg) neurons is lacking. We used extracellular single unit recordings to examine responses of NVg neurons to controlled whisker stimuli in three groups of animals: (1) rats whose whiskers were plucked from birth for 21 days; (2) rats whose whiskers were plucked once at 21 days of age; and (3) control animals. After at least 3 weeks of whisker re-growth, NVg neurons in plucked rats displayed normal, single whisker receptive fields and could be characterized as slowly (SA) or rapidly adapting (RA). The proportion of SA and RA neurons was unaffected by whisker plucking. Both SA and RA NVg neurons in plucked rats displayed normal response latencies and angular tuning but abnormally large responses to whisker movement onsets and offsets. SA neurons were affected to a greater extent than RA neurons. The effect of whisker plucking was more pronounced in animals whose whiskers were plucked repeatedly during development than in rats whose whiskers were plucked once. Individual neurons in plucked animals displayed abnormal periods of prolonged rhythmic firing following deflection onsets and aberrant bursts of activity during the plateau phase of the stimulus. These results indicate that whisker plucking exerts a long-term effect on responses of trigeminal ganglion neurons to peripheral stimulation.
对发育中和成年大鼠进行触须拔除，为暂时改变触觉输入提供了一种便捷方法，有助于研究体感皮层中依赖经验的可塑性。然而，目前缺乏对触须拔除对支配触须毛囊的三叉神经节（NVg）神经元反应特性影响的全面研究。我们采用细胞外单单位记录法，检测了三组动物的NVg神经元对可控触须刺激的反应：（1）从出生起触须被拔除21天的大鼠；（2）21日龄时触须被拔除一次的大鼠；（3）对照动物。在触须重新生长至少3周后，拔除触须的大鼠的NVg神经元表现出正常的单触须感受野，可分为慢适应（SA）或快适应（RA）神经元。SA和RA神经元的比例不受触须拔除的影响。拔除触须的大鼠的SA和RA NVg神经元均表现出正常的反应潜伏期和角度调谐，但对触须运动起始和结束的反应异常大。SA神经元比RA神经元受影响的程度更大。在发育过程中多次拔除触须的动物中，触须拔除的影响比只拔除一次触须的大鼠更明显。拔除触须的动物中的单个神经元在偏转起始后表现出异常的长时间节律性放电，在刺激的平台期出现异常的活动爆发。这些结果表明，触须拔除对三叉神经节神经元对外周刺激的反应产生长期影响。
