蛔虫的神经系统只有302个具有已知突触连接的神经细胞，然而它却执行很多与更复杂的生物相似的功能。这使得它非常适合让神经科学家来研究神经回路是怎样组织的。Chalasani等人对一种决定蛔虫觅食行为的神经回路进行了解剖研究。该回路允许探测气味的神经元激发或抑制下游的中间神经元，它们控制一致的爬行和转身行为。将遗传学和钙成像技术结合起来，可以对信息从环境中通过传感神经元向控制趋化性和觅食的中间神经元的流动进行跟踪。这一神经回路与哺乳动物视网膜中用来探测光的神经回路具有非常惊人的同源性，这是关于信息处理的保留策略或融合策略的一个明显例子。
原始出处:
Nature 450, 63-70 (1 November 2007) | doi:10.1038/nature06292; Received 14 August 2007; Accepted 24 September 2007
Dissecting a circuit for olfactory behaviour in Caenorhabditis elegans
Sreekanth H. Chalasani1, Nikos Chronis1, Makoto Tsunozaki1, Jesse M. Gray1, Daniel Ramot2, Miriam B. Goodman2 & Cornelia I. Bargmann1
Howard Hughes Medical Institute, Laboratory of Neural Circuits and Behaviour, The Rockefeller University, New York, New York 10065, USA
Program in Neurobiology and Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305, USA
Correspondence to: Cornelia I. Bargmann1 Correspondence and requests for materials should be addressed to C.I.B. (Email: cori@rockefeller.edu).
Abstract
Although many properties of the nervous system are shared among animals and systems, it is not known whether different neuronal circuits use common strategies to guide behaviour. Here we characterize information processing by Caenorhabditis elegans olfactory neurons (AWC) and interneurons (AIB and AIY) that control food- and odour-evoked behaviours. Using calcium imaging and mutations that affect specific neuronal connections, we show that AWC neurons are activated by odour removal and activate the AIB interneurons through AMPA-type glutamate receptors. The level of calcium in AIB interneurons is elevated for several minutes after odour removal, a neuronal correlate to the prolonged behavioural response to odour withdrawal. The AWC neuron inhibits AIY interneurons through glutamate-gated chloride channels; odour presentation relieves this inhibition and results in activation of AIY interneurons. The opposite regulation of AIY and AIB interneurons generates a coordinated behavioural response. Information processing by this circuit resembles information flow from vertebrate photoreceptors to 'OFF' bipolar and 'ON' bipolar neurons, indicating a conserved or convergent strategy for sensory information processing.
