Lavín A, Grace A A
Department of Behavioral Neuroscience, University of Pittsburgh, Pennsylvania 15260.
Synapse. 1994 Oct;18(2):104-27. doi: 10.1002/syn.890180205.
The actions mediated by limbic system output projections of the basal ganglia were investigated by studying the effects of ventral pallidum (VP) stimulation on the activity of neurons in thalamic target nuclei, including several of the dorsal thalamic nuclei and the nucleus reticularis, using in vivo intracellular recordings in rats. Intracellular injection of Lucifer yellow was used in a subset of experiments to identify the neurons recorded and to confirm their location with respect to the specific thalamic nuclei targeted. Stimulation of the VP evoked ipsps in 79% of the mediodorsal cells recorded. In the reticular nucleus, 73% of the neurons tested responded with evoked ipsps. In contrast, in other dorsal thalamic nuclei VP stimulation evoked depolarizations in 58% of the cells recorded. The latency to onset of the ipsps in the mediodorsal nucleus and in the reticular nucleus were not substantially different (1.7 +/- 1.1 msec vs. 2.7 +/- 1.1 msec), whereas the depolarizing response evoked in dorsal thalamic nucleus neurons typically occurred at longer and more variable latencies (3.5 +/- 2.7 msec). These experiments support a dual functional role for limbic system output from the basal ganglia in the regulation of thalamocortical activity: a) a direct inhibitory projection from the VP to the mediodorsal nucleus and b) an indirect disinhibition of neurons in other dorsal thalamic nuclei that occurs via a direct inhibitory projection to the reticular nucleus of the thalamus. Such an anatomical arrangement may be relevant to the presence of hypofrontality and the breakdown of cognitive filtering observed in schizophrenics.
通过在大鼠体内进行细胞内记录，研究腹侧苍白球（VP）刺激对丘脑靶核神经元活动的影响，以此来探究基底神经节边缘系统输出投射所介导的作用。这些靶核包括几个背侧丘脑核和丘脑网状核。在一部分实验中，通过细胞内注射路西法黄来识别所记录的神经元，并确认它们相对于特定丘脑靶核的位置。刺激VP可在79%的所记录的背内侧细胞中诱发抑制性突触后电位（ipsps）。在网状核中，73%的受试神经元对刺激产生了诱发的ipsps反应。相比之下，在其他背侧丘脑核中，VP刺激在58%的所记录细胞中诱发了去极化。背内侧核和网状核中ipsps开始的潜伏期没有显著差异（分别为1.7±1.1毫秒和2.7±1.1毫秒），而背侧丘脑核神经元诱发的去极化反应通常发生在更长且更具变化性的潜伏期（3.5±2.7毫秒）。这些实验支持了基底神经节边缘系统输出在丘脑皮质活动调节中的双重功能作用：a）从VP到背内侧核的直接抑制性投射；b）通过对丘脑网状核的直接抑制性投射，对其他背侧丘脑核神经元产生间接去抑制作用。这样的解剖学安排可能与精神分裂症患者中观察到的前额叶功能低下和认知过滤功能障碍有关。
