Holstege Gert
Department of Anatomy and Embryology, Faculty of Medical Sciences, University of Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
World J Urol. 2005 Jun;23(2):109-14. doi: 10.1007/s00345-004-0484-y. Epub 2005 May 4.
An overview is given of the regions in the spinal cord that are active during ejaculation. Motoneurons involved are the preganglionic sympathetic motoneurons in the upper lumbar spinal cord and the motoneurons in the nucleus of Onuf, located in the upper sacral cord. The first group is involved in the so-called emission phase of ejaculation, the last group in the expulsion phase. Both groups receive afferents from premotor interneurons in the so-called intermediomedial cell groups located at about the same level as the motoneurons themselves. A concept is put forward in which these premotor cell groups represent the central spinal pattern generators for ejaculation, one for the emission phase and one for the expulsion phase. Clinical observations in patients suffering from transection of the spinal cord indicate that the ejaculation motoneurons as well as their spinal central pattern generators are under strong influence of descending pathways originating in supraspinal parts of the brain. The various pathways possibly involved in ejaculation control are reviewed. Finally, the results of the brain activation of a PET-scan study in human males, ejaculating after penile stimulation by their female partner are discussed. Especially the ventral tegmental area and the cerebellum seem to be activated during ejaculation, while the amygdala region is deactivated. Apparently, a general lack of fear is necessary for ejaculation to occur.
本文概述了射精过程中脊髓内活跃的区域。涉及的运动神经元包括腰髓上段的节前交感运动神经元和位于骶髓上段的Onuf核内的运动神经元。第一组涉及射精的所谓射出期，最后一组涉及排出期。两组均接受来自所谓中间内侧细胞群内的运动前中间神经元的传入神经，这些中间内侧细胞群与运动神经元本身处于大致相同的水平。提出了一个概念，即这些运动前细胞群代表射精的脊髓中央模式发生器，一个用于射出期，一个用于排出期。脊髓横断患者的临床观察表明，射精运动神经元及其脊髓中央模式发生器受到起源于脑脊髓上部分的下行通路的强烈影响。本文回顾了可能参与射精控制的各种通路。最后，讨论了对男性进行PET扫描研究的结果，这些男性在接受女性伴侣阴茎刺激后射精。特别是腹侧被盖区和小脑在射精过程中似乎被激活，而杏仁核区域则被抑制。显然，射精发生需要普遍缺乏恐惧。
