Tamvacakis Arianna N, Lillvis Joshua L, Sakurai Akira, Katz Paul S
Department of Biology, University of Arkansas, Fayetteville, AR, United States.
Howard Hughes Medical Institute, Ashburn, VA, United States.
Front Behav Neurosci. 2022 Mar 3;16:855235. doi: 10.3389/fnbeh.2022.855235. eCollection 2022.
Gastropod mollusks are known for their large, individually identifiable neurons, which are amenable to long-term intracellular recordings that can be repeated from animal to animal. The constancy of individual neurons can help distinguish state-dependent or temporal variation within an individual from actual variability between individual animals. Investigations into the circuitry underlying rhythmic swimming movements of the gastropod species, and have uncovered intra- and inter-individual variability in synaptic connectivity and serotonergic neuromodulation. has a reliably evoked escape swim behavior that is produced by a central pattern generator (CPG) composed of a small number of identifiable neurons. There is apparent individual variability in some of the connections between neurons that is inconsequential for the production of the swim behavior under normal conditions, but determines whether that individual can swim following a neural lesion. Serotonergic neuromodulation of synaptic strength intrinsic to the CPG creates neural circuit plasticity within an individual and contributes to reorganization of the network during recovery from injury and during learning. In , variability over time in the modulatory actions of serotonin and in expression of serotonin receptor genes in an identified neuron directly reflects variation in swimming behavior. Tracking behavior and electrophysiology over hours to days was necessary to identify the functional consequences of these intra-individual, time-dependent variations. This work demonstrates the importance of unambiguous neuron identification, properly assessing the animal and network states, and tracking behavior and physiology over time to distinguish plasticity within the same animal at different times from variability across individual animals.
腹足纲软体动物以其大的、可单独识别的神经元而闻名，这些神经元适合进行长期细胞内记录，并且可以在不同动物之间重复进行。单个神经元的稳定性有助于将个体内的状态依赖性或时间变化与个体动物之间的实际变异性区分开来。对腹足纲动物有节奏的游泳运动背后的神经回路的研究发现了突触连接和血清素能神经调节中的个体内和个体间变异性。具有一种可靠诱发的逃避游泳行为，该行为由一个由少数可识别神经元组成的中枢模式发生器（CPG）产生。在正常情况下，神经元之间的一些连接存在明显的个体差异，这对游泳行为的产生无关紧要，但决定了该个体在神经损伤后是否能够游泳。CPG固有的突触强度的血清素能神经调节在个体内产生神经回路可塑性，并有助于在损伤恢复和学习过程中网络的重组。在中，血清素调节作用和血清素受体基因在一个已识别神经元中的表达随时间的变化直接反映了游泳行为的变化。跟踪数小时至数天的行为和电生理以确定这些个体内、时间依赖性变化的功能后果是必要的。这项工作证明了明确识别神经元、正确评估动物和网络状态以及随时间跟踪行为和生理以区分同一动物在不同时间的可塑性与个体动物之间变异性的重要性。
