Synaptic organization and plasticity of the input from the basolateral amygdala t

描述（由申请人提供）：味觉皮层（GC）接收来自边缘系统多个区域的调节输入。已知下丘脑外侧、内侧前额叶皮层、丘脑中背侧和基底外侧杏仁核（BLA）都向GC发送投射（Saper 1982; Allen, Saper et al. 1991; Maffei, Haley et al. 2012）。在这些输入中，BLA的输入是研究功能意义最多的输入。警觉性动物的药理学和电生理学实验表明，BLA的输入对于GC处理味觉刺激的享乐价值（Piette, Baez- Santiago et al. 2012）和味觉预测线索的预期价值（Samuelsen, Gardner et al. 2012）是必要的。此外，BLA-GC连接的可塑性变化与味觉厌恶学习有关（Guzman-Ramos and Bermudez-Rattoni 2012）。尽管有大量研究调查了BLA-GC连接的功能作用（Jones, French et al. 1999; Grossman, Fontanini et al. 2008; Guzman-Ramos and Bermudez-Rattoni 2012; Piette, Baez- Santiago et al. 2012; Parkes and Balleine 2013），但对这些输入的突触组织和可塑性知之甚少。来自体内细胞内和细胞外记录的证据表明，BLA-GC输入可能发挥复杂的兴奋和抑制作用（Yamamoto， Azuma等，1984；Hanamori等，2009;Stone， Maffei等，2011），但没有关于这些作用背后的突触机制的信息。此外，虽然对GC中BLA诱发电位的分析为该连接的学习相关可塑性提供了证据（Escobar, Chao et al. 1998; Jones, French et al. 1999; Escobar and Bermudez-Rattoni 2000; Rodriguez-Duran, Castillo et al. 2011），但这种可塑性的机制、规则和突触后靶点尚不清楚。直到最近，还不可能在体外选择性地激活BLA传入以精细地解剖杏仁核输入募集的GC回路。然而，光遗传学工具的可用性改变了这种情况（Zhang， Gradinaru等人，2010;Stuber， Sparta等人，2011;Yizhar， Fenno等人，2011；Britt和Bonci 2013； Wang， Kloc等人，2013），最终使我们能够解决与杏仁核传入GC的突触组织有关的基本问题。本文提出的实验依赖于这些新技术，结合体外全细胞膜片钳记录，直接测量锥体细胞上的杏仁核突触和GC中抑制性中间神经元的特性。该方法将与药理学和行为学操作相辅相成，以验证以下假设：1)BLA传入在GC局部电路中直接与不同类型的细胞建立功能性突触；2)锥体神经元和抑制性中间神经元的突触输入表现出活动依赖的可塑性；3)快乐学习影响BLA- GC突触的强度。总之，这些实验将使我们能够研究BLA-GC输入的突触组织，它们的可塑性以及与厌恶学习相关的变化。这个框架代表了一种全新的方法来研究大脑切片中的GC输入，并有望提供味觉皮层中杏仁核突触的第一个电路级描述。

DESCRIPTION (provided by applicant): The gustatory cortex (GC) receives modulatory inputs from multiple regions of the limbic system. Lateral hypothalamus, medial prefrontal cortex, mediodorsal thalamus and basolateral amygdala (BLA) are all known to send projections to GC (Saper 1982; Allen, Saper et al. 1991; Maffei, Haley et al. 2012). Among these inputs, those from the BLA are the ones whose functional significance has been studied the most. Pharmacological and electrophysiological experiments in alert animals have suggested that inputs from BLA are necessary for GC to process information pertaining to the hedonic value of gustatory stimuli (Piette, Baez- Santiago et al. 2012) and the anticipatory value of taste-predictive cues (Samuelsen, Gardner et al. 2012). In addition, plastic changes of the BLA-GC connection have been associated with taste aversion learning (Guzman-Ramos and Bermudez-Rattoni 2012). Despite the abundance of studies investigating the functional role of the BLA-GC connection (Jones, French et al. 1999; Grossman, Fontanini et al. 2008; Guzman-Ramos and Bermudez-Rattoni 2012; Piette, Baez- Santiago et al. 2012; Parkes and Balleine 2013), very little is known on the synaptic organization and plasticity of these inputs. Evidence from intracellular and extracellular recordings in vivo suggests that BLA-GC inputs might exert complex excitatory as well as inhibitory actions (Yamamoto, Azuma et al. 1984; Hanamori 2009; Stone, Maffei et al. 2011), yet no information is available on the synaptic mechanisms underlying these effects. Furthermore, while analysis of BLA evoked potentials in GC provides evidence for learning-related plasticity at this connection (Escobar, Chao et al. 1998; Jones, French et al. 1999; Escobar and Bermudez-Rattoni 2000; Rodriguez-Duran, Castillo et al. 2011), the mechanisms, rules and postsynaptic targets of this plasticity are unknown. Until recently it has been impossible to selectively activate BLA afferents in vitro to finely dissect th GC circuits recruited by amygdalar inputs. The availability of optogenetic tools has however changed the situation (Zhang, Gradinaru et al. 2010; Stuber, Sparta et al. 2011; Yizhar, Fenno et al. 2011; Britt and Bonci 2013; Wang, Kloc et al. 2013), finally allowing us the fundamental questions pertaining to the synaptic organization of amygdalar afferents to GC to be addressed. The experiments proposed here rely on these novel techniques, combined with in vitro whole cell patch clamp recordings, to directly measure the properties of amygdalar synapses onto pyramidal cells and inhibitory interneurons in GC. This methodological approach will be complemented with pharmacological and behavioral manipulations to test the following hypotheses: 1) BLA afferents make direct functional synapses onto different cell types within GC local circuits; 2) Synaptic inputs onto pyramidal neurons and inhibitory interneurons show activity-dependent plasticity; 3) The strength of BLA- GC synapses is affected by hedonic learning. Altogether these experiments will allow us to investigate the synaptic organization of BLA-GC inputs, their plasticity and the changes associated with aversion learning. This framework represents an entirely novel approach to the study of GC inputs in brain slices and promises to provide the first circuit-level description of amygdalar synapses in the gustatory cortex.