Population coding of electrosensory stimulus in receptor network

To investigate the mechanism of sensory coding of spatiotemporally varying stimuli, we study the population coding of receptor network in electrosensory system. Weakly electric fish use amplitude modulations of their self-generated electric organ discharge (EOD AM) to detect distance and size of an object such as prey. We developed a model of fish by which we calculate numerically the spatiotemporal patterns of electric field around the fish body, and made a model of electroreceptor network. We showed previously that the information of object distance and size are represented by a combination of two characteristic features of EOD AM, the maximum amplitude and half-maximum width of EOD AM. We show here that the information of object distance and its size are encoded as synchronous firing of receptor network, leading to a reliable encoding of the two features of EOD AM in target neurons to which the receptors project, through a rapid synaptic integration of the receptor outputs. We further show that an optimal distribution of receptor sensitivity to EOD stimuli may provide a significant change of the two EOD AM features depending on object distance.