Kovac M P, Davis W J, Matera E M, Morielli A, Croll R P
Brain Res. 1985 Apr 8;331(2):275-84. doi: 10.1016/0006-8993(85)91553-7.
The neural manifestations of food avoidance learning in the mollusc, Pleurobranchaea, survive the surgical reduction of the preparation to the nearly isolated brain. These manifestations include increased synaptic inhibition and reduced synaptic excitation of the phasic paracerebral feeding command interneurons (PCps) in the brain in response to food stimulation of chemosensory structures left attached to the brain. The same changes are not evident, however, in brains removed from naive, control or satiated specimens. Therefore the nearly isolated brain preparation permits analysis of the cellular substrates of learning in relative isolation from non-associative motivational variables. The isolated brain preparation is here used to show that the increased synaptic inhibition consequent to associative training is distributed not only to the PCps but also to their identified central presynaptic inputs, including other identified feeding command interneurons (PSEs and ETIIs; ref. 21). The decrease in PCp excitation is explained in part by a training-induced inhibition of excitatory inputs to the PCps, and in part by a training-induced reduction in the efficacy of an identified polysynaptic excitatory pathway presynaptic to the PCps.
在软体动物侧鳃中，食物回避学习的神经表现能够在将标本手术简化为近乎孤立的大脑后依然存在。这些表现包括，在对附着于大脑的化学感应结构进行食物刺激时，大脑中阶段性脑旁进食指令中间神经元（PCps）的突触抑制增强，突触兴奋减弱。然而，在从未经训练的、对照或饱腹标本中取出的大脑中，同样的变化并不明显。因此，近乎孤立的大脑标本能够在相对独立于非联想动机变量的情况下，对学习的细胞基质进行分析。在此，使用孤立的大脑标本以表明，联想训练导致的突触抑制增强不仅分布于PCps，还分布于其已确定的中枢突触前输入，包括其他已确定的进食指令中间神经元（PSEs和ETIIs；参考文献21）。PCp兴奋的降低部分是由训练诱导的对PCps兴奋性输入的抑制所致，部分是由训练诱导的PCps突触前一条已确定的多突触兴奋性通路效能降低所致。
