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This Article Full Text Full Text (PDF) All Versions of this Article: 93/5/2898    most recent 01051.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Saito, Y. Articles by Isa, T. Search for Related Content PubMed PubMed Citation Articles by Saito, Y. Articles by Isa, T.

Organization of Interlaminar Interactions in the Rat Superior Colliculus

¹Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki; and ²Department of Neurophysiology, Gunma University Graduate School of Medicine, Gunma, Japan

Submitted 6 October 2004; accepted in final form 10 December 2004

Our previous studies have shown that when slices of the rat superior colliculus (SC) are exposed to a solution containing 10 µM bicuculline and a low concentration of Mg²⁺ (0.1 mM), most neurons in the intermediate gray layer (stratum griseum intermediale; SGI), wide-field vertical (WFV) cells in the optic layer (stratum opticum; SO), and a minor population of neurons in the superficial gray layer (stratum griseum superficiale; SGS) exhibit spontaneous depolarization and burst firing, which are synchronous among adjacent neurons. These spontaneous and synchronous depolarizations were thought to share common mechanisms with presaccadic burst activity in SGI neurons. In the present study, we explored the site responsible for generation of synchronous depolarization of SGI neurons by performing dual whole cell recordings under different slice conditions. A pair of SGI neurons recorded in a small rectangular piece of the SGI punched out from the SC slice showed synchronous depolarization but far less frequently than those recorded in a small rectangular piece including SGS and SO. This suggests that the superficial layers are needed for triggering synchronous depolarization in the SGI. Furthermore, we recorded spontaneous depolarizations in pairs of neurons belonging to the different layers. Analysis of their synchronicity revealed that WFV cells in the SO exhibit synchronous depolarizations with both SGS and SGI neurons, and the onset of spontaneous depolarization in WFV cells precedes those of neurons in other layers. Further, when SGS and SGI neurons exhibit synchronous depolarizations, SGI neurons usually precede the SGS neurons. These observations give further evidence to the existence of interlaminar interaction between superficial and deeper layers of the SC. In addition, it is suggested that WFV cells can trigger burst activity in other layers of the SC and that there is an excitatory signal transmission from the deeper layers to the superficial layers.

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