Form and function: adapting dendritic morphology and synaptic location to optimise neural activity

神经元有着非凡的形态，有着精心分支的树突和精确定位的突触。是什么决定了神经元的形状？它们的解剖结构能在多大程度上被调整以优化神经元生理学？我们在果蝇（Drosophila）中解决了这个问题，在果蝇中，嗅觉联想记忆存储在称为凯尼恩细胞的神经元中。我们最近的建模工作预测，为了最大限度地提高记忆容量，所有的凯尼恩细胞都应该是同样兴奋的，尽管它们的内在兴奋性可变，但要达到同样的活性需要代偿性变异（例如，具有比通常更高的尖峰阈值的凯尼恩细胞也具有比通常更强的突触输入。凯尼恩细胞是否调整其形态以补偿其他参数的变化？例如，具有低于通常的尖峰阈值的凯尼恩细胞可能通过延长/缩小其树突或将兴奋性突触放置在更远的位置来降低其兴奋性，使得输入信号在到达尖峰起始区之前减弱。

Neurons have remarkable morphologies, with elaborately branching dendrites and precisely placed synapses. What determines the shape of neurons? To what extent can their anatomy be tuned to optimise neuronal physiology? We address this question in the fruit fly Drosophila, where olfactory associative memories are stored in neurons called Kenyon cells. Our recent modelling work predicts that, to maximise memory capacity, all Kenyon cells should be equally excitable, and that achieving equal activity despite their variable intrinsic excitability requires compensatory variability (e.g., Kenyon cells with higher-than-usual spiking thresholds also have stronger-than-usual synaptic inputs). Do Kenyon cells tune their morphology to compensate for variability in other parameters? For example, a Kenyon cell with lower-than-usual spiking threshold might reduce its excitability by lengthening/narrowing its dendrites or placing excitatory synapses more distally, so that input signals weaken before they reach the spike initiation zone.