Panagis G, Miliaressis E, Anagnostakis Y, Spyraki C
Department of Basic Sciences, School of Medicine, University of Crete, Heraklion, Greece.
Behav Brain Res. 1995 Jun;68(2):165-72. doi: 10.1016/0166-4328(94)00169-g.
The distribution of electrical self-stimulation (ESS) foci within the ventral pallidum (VP) was mapped using moveable electrodes in rats. The function relating ESS bar-pressing rate to the frequency of cathodal rectangular pulses (0.4 mA and 0.1 ms) was obtained for several positions of a moveable electrode in the VP and in the various adjacent to VP nuclei. The rate-frequency functions were fitted to a sigmoid model to obtain the asymptotic rate and threshold frequency. ESS was found in almost all (98%) VP sites tested and to a lesser degree (66%) in the surrounding areas (namely globus pallidus and caudate). Depending on the VP site, maximum rates varied from 14 to 85 bar presses/min, whereas threshold frequencies varied from 10.2 to 36.4 pulses/train; no correlation between these two aspects of ESS was found. Extra-pallidal areas contained less low-frequency threshold sites compared to VP. The lowest threshold found in the VP was slightly higher than that usually obtained for the most rewarding brain areas (VTA, dorsal raphé, LH, amygdala), which suggests that the VP represents an important structure for reward. Furthermore the threshold frequencies were found to decline along the rostrocaudal axis of the VP which supports the view that the VP is heterogeneous in regard to reward related functions.
使用可移动电极在大鼠中绘制腹侧苍白球（VP）内电自我刺激（ESS）焦点的分布图。针对VP中可移动电极的几个位置以及与VP相邻的各个核，获得了ESS压杆速率与阴极矩形脉冲频率（0.4 mA和0.1 ms）之间的函数关系。将速率-频率函数拟合到S形模型以获得渐近速率和阈值频率。在几乎所有（98%）测试的VP位点都发现了ESS，在周围区域（即苍白球和尾状核）发现的程度较低（66%）。根据VP位点的不同，最大速率从每分钟14次到85次压杆不等，而阈值频率从每次训练10.2次到36.4次脉冲不等；未发现ESS的这两个方面之间存在相关性。与VP相比，苍白球外区域包含的低频阈值位点较少。在VP中发现的最低阈值略高于通常在最具奖赏性的脑区（腹侧被盖区、中缝背核、外侧下丘脑、杏仁核）获得的阈值，这表明VP是一个重要的奖赏结构。此外，发现阈值频率沿VP的前后轴下降，这支持了VP在奖赏相关功能方面是异质性的观点。
