节律运动行为的振荡网络,感觉和复杂的神经处理,是灵活的,甚至在它们的神经元组成中。神经调制输入使神经元能够在网络之间切换参与,或同时参与多个网络。网络间突触的神经调节可以招募和协调第二网络中的转换神经元。我们先前确定了一个例子,其中神经元通过内在特性的肽能调节被招募到双网络活动中。我们现在询问相同的神经肽是否也调节网络间突触以进行网络间协调。螃蟹(癌症)口胃神经系统包含两个明确定义的喂养相关网络(幽门,食物过滤,~1Hz;胃磨,食物咀嚼,~0.1Hz)。投射神经元MCN5使用神经肽Gly1-SIFamide通过调节LPG的内在特性,将仅幽门的LPG神经元募集到双幽门加胃镜定时爆发中。对于协调的节奏,不需要降序输入,因此,LPG及其第二个网络之间的网络内突触必须是这些神经元之间协调的基础。然而,LPG和胃磨神经元之间的突触尚未被记录。使用双电极电压钳记录,我们发现液化石油气和胃磨神经元之间的渐变突触电流(LG,IC,DG)在盐水中主要可以忽略不计,但被Gly1-SIFamide增强。Further,在Gly1-SIFamide应用期间,LPG和胃磨神经元相互夹带,指示双向,功能连接。因此,神经肽通过平行作用介导神经元转换,将招募的内在属性调制到第二个网络中,如图所示,还调制双向网络突触以进行协调。
Oscillatory networks underlying rhythmic motor behaviors, and sensory and complex neural processing, are flexible, even in their neuronal composition. Neuromodulatory inputs enable neurons to switch participation between networks or participate in multiple networks simultaneously. Neuromodulation of internetwork synapses can both recruit and coordinate a switching neuron in a second network. We previously identified an example in which a neuron is recruited into dual-network activity via peptidergic modulation of intrinsic properties. We now ask whether the same neuropeptide also modulates internetwork synapses for internetwork coordination. The crab (Cancer borealis) stomatogastric nervous system contains two well-defined feeding-related networks (pyloric, food filtering, ∼1 Hz; gastric mill, food chewing, ∼0.1 Hz). The projection neuron MCN5 uses the neuropeptide Gly1-SIFamide to recruit the pyloric-only lateral posterior gastric (LPG) neuron into dual pyloric- plus gastric mill-timed bursting via modulation of LPG\'s intrinsic properties. Descending input is not required for a coordinated rhythm, thus intranetwork synapses between LPG and its second network must underlie coordination among these neurons. However, synapses between LPG and gastric mill neurons have not been documented. Using two-electrode voltage-clamp recordings, we found that graded synaptic currents between LPG and gastric mill neurons (lateral gastric, inferior cardiac, and dorsal gastric) were primarily negligible in saline, but were enhanced by Gly1-SIFamide. Furthermore, LPG and gastric mill neurons entrain each other during Gly1-SIFamide application, indicating bidirectional, functional connectivity. Thus, a neuropeptide mediates neuronal switching through parallel actions, modulating intrinsic properties for recruitment into a second network and as shown here, also modulating bidirectional internetwork synapses for coordination.NEW & NOTEWORTHY Neuromodulation can enable neurons to simultaneously coordinate with separate networks. Both recruitment into, and coordination with, a second network can occur via modulation of internetwork synapses. Alternatively, recruitment can occur via modulation of intrinsic ionic currents. We find that the same neuropeptide previously determined to modulate intrinsic currents also modulates bidirectional internetwork synapses that are typically ineffective. Thus, complementary modulatory peptide actions enable recruitment and coordination of a neuron into a second network.