Department of Neuroscience, Mount Sinai School of Medicine, New York, New York 10029, USA.
J Neurosci. 2013 Feb 27;33(9):3786-98. doi: 10.1523/JNEUROSCI.5371-12.2013.
Behavioral states often preferentially enhance specific classes of behavior and suppress incompatible behaviors. In the nervous system, this may involve upregulation of the efficacy of neural modules that mediate responses to one stimulus and suppression of modules that generate antagonistic or incompatible responses to another stimulus. In Aplysia, prestimulation of egestive inputs [esophageal nerve (EN)] facilitates subsequent EN-elicited egestive responses and weakens ingestive responses to ingestive inputs [Cerebral-Buccal Interneuron (CBI-2)]. However, a single state can also promote incompatible behaviors in response to different stimuli. This is the case in Aplysia, where prestimulation of CBI-2 inputs not only enhances subsequent CBI-2-elicited ingestive responses, but also strengthens EN-elicited egestive responses. We used the modularly organized feeding network of Aplysia to characterize the organizational principles that allow a single network state to promote two opposing behaviors, ingestion and egestion, without the two interfering with each other. We found that the CBI-2 prestimulation-induced state upregulates the excitability of neuron B65 which, as a member of the egestive module, increases the strength of egestive responses. Furthermore, we found that this upregulation is likely mediated by the actions of the neuropeptides FCAP (Feeding Circuit Activating Peptide) and CP2 (Cerebral Peptide 2). This increased excitability is mediated by a form of modulation that we refer to as "latent modulation" because it is established during stimulation of CBI-2, which does not activate B65. However, when B65 is recruited into EN-elicited egestive responses, the effects of the latent modulation are expressed as a higher B65 firing rate and a resultant strengthening of the egestive response.
行为状态通常优先增强特定类别的行为，并抑制不兼容的行为。在神经系统中，这可能涉及上调介导对一种刺激的反应的神经模块的效力，并抑制产生对另一种刺激的拮抗或不兼容反应的模块。在海兔中，消化输入（食管神经（EN））的预先刺激促进随后的 EN 引发的消化反应，并减弱对摄取输入（脑 - 颊中间神经元（CBI-2））的摄取反应。然而，单一状态也可以促进对不同刺激的不兼容行为。在海兔中就是这种情况，其中 CBI-2 输入的预先刺激不仅增强了随后的 CBI-2 引发的摄取反应，而且还增强了 EN 引发的消化反应。我们使用海兔组织良好的摄食网络来描述允许单个网络状态促进两种相反行为（摄取和消化）而不相互干扰的组织原则。我们发现，CBI-2 预先刺激诱导的状态上调了神经元 B65 的兴奋性，作为消化模块的成员，B65 的兴奋性增加了消化反应的强度。此外，我们发现这种上调可能是由神经肽 FCAP（摄食回路激活肽）和 CP2（脑肽 2）的作用介导的。这种兴奋性增加是通过我们称为“潜在调制”的调制形式介导的，因为它是在 CBI-2 刺激期间建立的，而 CBI-2 不会激活 B65。然而，当 B65 被招募到 EN 引发的消化反应中时，潜在调制的效果表现为更高的 B65 放电率和消化反应的增强。
