The emergence of the cerebral cortex and its dramatic increase in size during vertebrate evolution suggest that it employs computations that are highly advantageous. However, despite decades of intensive research and major advances in our knowledge of the molecular machinery underlying cortical functions, we still lack an understanding of these computations.
To learn about these computations we are taking a unique approach by studying the "simpler" cortex of reptiles. In contrast to the six-layered cortex of mammals, the reptilian cortex is characterized by a reduced three-layered structure and is sub-divided into medial, dorsal and lateral parts, which are considered to be homologous to the mammalian hippocampus, isocortex, and piriform cortex, respectively. On the single cell level, cortical neurons seem to share many properties with their mammalian counter-parts. Shared properties are also found on the population level, where cortical activities exhibit rich dynamical profiles, including travelling waves, oscillations, sharp waves, slow waves and self-organized criticality (Shein-Idelson et al, Science, 2016).
We are employing a methodology we recently developed which allows to record hundreds to thousands of neurons from the entire area of this cortex (Shein-Idelson et al 2017). We are using this methodology to study how the red-eared sliders' (trachemys scripta elegans) cortex processes visual stimuli and how the structural organization of dorsal cortex supports this function. Charting this unmapped territory can significantly contribution to our understanding of forebrain evolution and dynamics. Moreover, insights from these simpler cortices have the potential of exposing fundamental computational principles that may be otherwise masked in mammalian brains.