Reciprocal connection between the ventral tegmental area (VTA) and the hippocampus forms a loop that controls information entry into long-term memory. Compared with the widely studied VTA dopamine system, VTA glutamate terminals are anatomically dominant in the hippocampus and less understood. The current study employs anterograde and retrograde labeling of VTA dopamine and glutamate neurons to map the distribution of their terminals within the layers of the hippocampus. Also, functional tracing of VTA dopamine and glutamate projections to the hippocampus was performed by photostimulation of VTA cell bodies during CA1 extracellular voltage sampling in vivo. VTA dopamine terminals predominantly innervate the CA1 basal dendrite layer and modulate the firing rate of active putative neurons. In contrast, anatomical dominance of VTA glutamate terminals in the CA1 pyramidal cell and apical dendrite layers suggests the possible involvement of these terminals in excitability regulation. In support of these outcomes, photostimulation of VTA dopamine neurons increased the firing rate but not intrinsic excitability parameters for putative pyramidal units. Conversely, activation of VTA glutamate neurons increased CA1 network firing rate and burst rate. In addition, VTA glutamate inputs reduced the interspike and interburst intervals for putative CA1 neurons. Taken together, we deduced that layer-specific distribution of presynaptic dopamine and glutamate terminals in the hippocampus determinines VTA modulation (dopamine) or regulation (glutamate) of excitability in the CA1 neural network.

腹侧被盖区（VTA）与海马体之间的相互连接形成一个环，该环控制信息输入到长期记忆中。与广泛研究的VTA多巴胺系统相比，VTA谷氨酸末端在海马体中在解剖学上占主导地位，并且鲜为人知。当前的研究采用VTA多巴胺和谷氨酸神经元的顺行和逆行标记来绘制海马层内其末端的分布图。此外，通过在体内CA1细胞外电压采样过程中对VTA细胞体进行光刺激来执行VTA多巴胺和谷氨酸向海马的功能追踪。VTA多巴胺末端主要支配CA1基底树突层并调节活性推定神经元的放电速率。相比之下，CA1锥体细胞和顶端树突层中VTA谷氨酸末端的解剖学优势表明这些末端可能参与了兴奋性调节。为了支持这些结果，VTA多巴胺神经元的光刺激提高了发射速率，但没有增加假定的锥体单元的内在兴奋性参数。相反，VTA谷氨酸神经元的激活增加了CA1网络的激发率和爆发率。此外，VTA谷氨酸输入减少了假定的CA1神经元的突突和突突间隔。在一起