In case someone is interested in exon-silencing / splicing regulatory motifs in neuronal cells:
An P, Grabowski PJ (2007) Exon Silencing by UAGG Motifs in Response to Neuronal Excitation. PLoS Biol 5(2): e36 doi:10.1371/journal.pbio.0050036
The paper describes a KCL dependen exon silencing.
I made a rough guess about the C.elegans ortholog of GRIN1 which is one of the examples in the paper and it might be WBGene00012176 / W01C9.2 (WS170).
It has all described motifs, both ESS (UAGG) and the single ISS (GGGG) which are reported to be hnRNP A1 mediated.
And in addition the C.elegans gene seems to be expressed in neuronal cells (SAGE-tags) like the rat GRIN1.
Michael Han