Hamel Laurie, Thangarasa Tharshika, Samadi Osai, Ito Rutsuko
Department of Psychology (Scarborough), University of Toronto , 1265 Military Trail , Toronto, Ontario M1C 1A4, Canada.
Department of Psychology (Scarborough), University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada; Department of Cell and Systems Biology, Ramsay Wright Laboratories, University of Toronto, 25 Harbord Street, Toronto, Ontario M5S 3G5, Canada.
eNeuro. 2017 Feb 15;4(1). doi: 10.1523/ENEURO.0330-16.2017. eCollection 2017 Jan-Feb.
The nucleus accumbens (NAc) is thought to be a site of integration of positively and negatively valenced information and action selection. Functional differentiation in valence processing has previously been found along the rostrocaudal axis of the shell region of the NAc in assessments of unconditioned motivation. Given that the core region of the NAc has been implicated in the elicitation of motivated behavior in response to conditioned cues, we sought to assess the role of caudal, intermediate, and rostral sites within this subregion in cue-elicited approach-avoidance decisions. Rats were trained to associate visuo-tactile cues with appetitive, aversive, and neutral outcomes. Following the successful acquisition of the cue-outcome associations, rats received microinfusions of GABA and GABA receptor agonists (muscimol/baclofen) or saline into the caudal, intermediate, or rostral NAc core and were then exposed to a superimposition of appetitively and aversively valenced cues versus neutral cues in a "conflict test," as well as to the appetitive versus neutral cues, and aversive cues versus neutral cues, in separate conditioned preference/avoidance tests. Disruption of activity in the intermediate to caudal parts of the NAc core resulted in a robust avoidance bias in response to motivationally conflicting cues, as well as a potentiated avoidance of aversive cues as compared with control animals, coupled with an attenuated conditioned preference for the appetitive cue. These results suggest that the caudal NAc core may have the capacity to exert bidirectional control over appetitively and aversively motivated responses to valence signals.
伏隔核（NAc）被认为是正性和负性价态信息整合以及行动选择的场所。在无条件动机评估中，先前已发现NAc壳区沿前后轴在价态加工方面存在功能分化。鉴于NAc的核心区域与对条件线索做出反应时激发动机行为有关，我们试图评估该亚区域内尾侧、中间和头侧部位在线索引发的趋近-回避决策中的作用。训练大鼠将视觉-触觉线索与奖赏性、厌恶型和中性结果联系起来。在成功建立线索-结果关联后，给大鼠在尾侧、中间或头侧NAc核心微量注射γ-氨基丁酸（GABA）及其GABA受体激动剂（蝇蕈醇/巴氯芬）或生理盐水，然后在“冲突测试”中将奖赏性和厌恶型价态线索与中性线索叠加呈现给大鼠，同时在单独的条件性偏好/回避测试中将奖赏性线索与中性线索、厌恶型线索与中性线索分别呈现给大鼠。与对照动物相比，NAc核心中间至尾侧部分的活动受到干扰会导致大鼠在面对动机冲突线索时产生强烈的回避偏向，同时对厌恶型线索的回避增强，而对奖赏性线索的条件性偏好减弱。这些结果表明，尾侧NAc核心可能有能力对奖赏性和厌恶型动机对价态信号的反应施加双向控制。
