The lizard Anolis carolinensis is an interesting model organism in cognitive neuroscience as it possesses an evolutionary very early hippocampal homolog but no neocortex. Whereas behavioral studies suggest that lizards are able to perform similar hippocampus-dependent cognitive tasks as mammals, it is not known whether the functional organization in reptiles is the same as in mammals. One way to probe functional architecture is to investigate neural representations across different subregions, e.g. by immediate early gene imaging, which visualizes genomic responses of activated neuronal populations. Here we explore whether compartmental analysis of temporal activity by fluorescence in-situ hybridisation (catFISH) of the immediate early gene zif268/erg1 can be used in lizards to investigate neural representations across hippocampal subfields.Funded by CRC1461.