Cinelli A R, Ferreyra-Moyano H, Barragan E
Instituto de Investigacion Medica Mercedes y Martin Ferreyra, Cordoba, Argentina.
Brain Res Bull. 1987 Dec;19(6):651-61. doi: 10.1016/0361-9230(87)90051-7.
Reciprocal putative connections of the prefrontal cortex (PFC) (agranular insular, ventral and lateral orbital region) with the ipsi and contralateral main olfactory bulb (IOB; COB), the mediodorsal thalamic nucleus (MD), the basolateral amygdaloid nucleus (BLA) and the piriform cortex (PC) were investigated with electrophysiological techniques. Evoked field responses and orthodromic unit driving, generated in PFC following electrical stimulation of the above mentioned structures, were abolished following topical application of KCl, except for COB evoked mass potentials. Thus, locally generated activity was elicited in agranular insular cortex following IOB activation, the same region where recently, the taste cortex in the rat was localized. Since gustatory-visceral afferent information reaches insular cortex via 2-3 synaptic relays, autonomic, olfactory and gustatory inputs may interact at this level, and, as suggested previously for the mouse, play a key integrative role in flavor perception. Antidromically invaded neurons, 47% of which were identified by the collision-extinction technique, were also found in PFC areas which overlapped to a considerable extent with those from which orthodromic unit responses were obtained. In particular, closely spaced neurons in ventrolateral orbital (VLO) and lateral orbital (LO) regions were antidromically invaded following IOB and PC shocks; some neurons antidromically discharged by IOB were also transsynaptically activated following PC stimulation. These findings are in agreement with recent neuroanatomical studies which demonstrate axonal projections from PFC neurons to the IOB and COB in the rat and South American armadillo. In addition, stimulation of PFC regions dorsal to the rhinal fissure mostly inhibited spontaneous unit discharges recorded at the mitral cell layer of the IOB, suggesting that this effect may be partially mediated by excitatory inputs of prefrontal axons onto granule cells. The conduction properties, antidromic thresholds and activity-dependent variations in conduction velocity (CV) of bulbopetal neurons in prefrontal cortex were found to be similar to those exhibited by cells projecting to the IOB from olfactory peduncle regions, but not to those present in bulbopetal neurons of the horizontal limb of diagonal band, indicating that the OB may be subjected to centrifugal control by at least two cell groups differing in both histochemical and electrophysiological properties.
采用电生理技术研究了前额叶皮质（PFC）（无颗粒岛叶、腹侧和外侧眶区）与同侧及对侧主嗅球（IOB；COB）、丘脑背内侧核（MD）、杏仁核基底外侧核（BLA）和梨状皮质（PC）之间的相互假定连接。在对上述结构进行电刺激后，PFC中产生的诱发电场反应和正行单位驱动，在局部应用氯化钾后消失，但COB诱发的群体电位除外。因此，在IOB激活后，无颗粒岛叶皮质中引发了局部产生的活动，该区域最近被定位为大鼠的味觉皮质。由于味觉 - 内脏传入信息通过2 - 3个突触中继到达岛叶皮质，自主神经、嗅觉和味觉输入可能在这个水平上相互作用，并且，如先前对小鼠所建议的，在味觉感知中发挥关键的整合作用。在PFC区域也发现了逆向侵入的神经元，其中47%通过碰撞 - 消减法鉴定，这些区域与获得正行单位反应的区域有相当程度的重叠。特别是，在腹外侧眶（VLO）和外侧眶（LO）区域紧密排列的神经元在IOB和PC电击后发生逆向侵入；一些被IOB逆向放电的神经元在PC刺激后也被跨突触激活。这些发现与最近的神经解剖学研究一致，这些研究表明大鼠和南美犰狳中PFC神经元向IOB和COB的轴突投射。此外，刺激鼻裂背侧的PFC区域大多抑制了在IOB的二尖瓣细胞层记录到的自发单位放电，表明这种效应可能部分由前额叶轴突对颗粒细胞的兴奋性输入介导。发现前额叶皮质中向嗅球投射的神经元的传导特性、逆向阈值和传导速度（CV）的活动依赖性变化与从嗅柄区域投射到IOB的细胞所表现出的相似，但与斜角带水平支中向嗅球投射的神经元不同，这表明嗅球可能受到至少两个在组织化学和电生理特性上不同的细胞群的离心控制。
