Department of Psychology, Rutgers University, New Brunswick, New Jersey 08903, USA.
J Comp Neurol. 2013 Feb 15;521(3):558-88. doi: 10.1002/cne.23191.
The ventral pallidum (VP) is necessary for drug-seeking behavior. VP contains ventromedial (VPvm) and dorsolateral (VPdl) subregions, which receive projections from the nucleus accumbens shell and core, respectively. To date no study has investigated the behavioral functions of the VPdl and VPvm subregions. To address this issue, we investigated whether changes in firing rate (FR) differed between VP subregions during four events: approaching toward, responding on, or retreating away from a cocaine-reinforced operandum and a cocaine-associated cue. Baseline FR and waveform characteristics did not differ between subregions. VPdl neurons exhibited a greater change in FR compared with VPvm neurons during approaches toward, as well as responses on, the cocaine-reinforced operandum. VPdl neurons were more likely to exhibit a similar change in FR (direction and magnitude) during approach and response than VPvm neurons. In contrast, VPvm firing patterns were heterogeneous, changing FRs during approach or response alone, or both. VP neurons did not discriminate cued behaviors from uncued behaviors. No differences were found between subregions during the retreat, and no VP neurons exhibited patterned changes in FR in response to the cocaine-associated cue. The stronger, sustained FR changes of VPdl neurons during approach and response may implicate VPdl in the processing of drug-seeking and drug-taking behavior via projections to subthalamic nucleus and substantia nigra pars reticulata. In contrast, the heterogeneous firing patterns of VPvm neurons may implicate VPvm in facilitating mesocortical structures with information related to the sequence of behaviors predicting cocaine self-infusions via projections to mediodorsal thalamus and ventral tegmental area.
腹侧苍白球（VP）是寻求药物行为所必需的。VP 包含腹内侧（VPvm）和背外侧（VPdl）两个亚区，分别接收来自伏隔核壳和核心的投射。迄今为止，尚无研究调查过 VPdl 和 VPvm 亚区的行为功能。为了解决这个问题，我们调查了在四个事件期间，VP 亚区的放电率（FR）变化是否不同：接近、响应或从可卡因强化操作器和可卡因相关线索上撤退。亚区之间的基线 FR 和波形特征没有差异。与 VPvm 神经元相比，VPdl 神经元在接近以及对可卡因强化操作器的反应过程中，其 FR 变化更大。与 VPvm 神经元相比，VPdl 神经元在接近和反应过程中更有可能表现出相似的 FR 变化（方向和幅度）。相比之下，VPvm 的发射模式是多样的，仅在接近或反应过程中或两者都改变 FR。VP 神经元不能区分有线索和无线索的行为。在撤退过程中，亚区之间没有发现差异，也没有 VP 神经元对可卡因相关线索表现出模式化的 FR 变化。VPdl 神经元在接近和反应过程中更强、持续的 FR 变化，可能暗示 VPdl 通过投射到丘脑底核和黑质网状部参与药物寻求和药物摄取行为的处理。相比之下，VPvm 神经元的异质发射模式可能暗示 VPvm 通过投射到背内侧丘脑和腹侧被盖区，促进与预测可卡因自我输注行为序列相关的信息从中脑皮质结构传递。
