The functional architecture, receptive field characteristics, and representation of objects in the visual network of the pigeon brain.

We provide an extensive review of the pigeon visual system, focussing on the known cell types, receptive field characteristics, mechanisms of perception/visual attention, and projection profiles of neurons in the thalamofugal and tectofugal pathways. The similarities and differences with the primate visual system at each stage of the visual hierarchy are highlighted. We conclude with a discussion of object and face processing in birds, as well as the current state of knowledge in the search for face-selective neurons in the avian visual system.

Searching for Face-Category Representation in the Avian Visual Forebrain.

Visual information is processed hierarchically along a ventral ('what') pathway that terminates with categorical representation of biologically relevant visual percepts (such as faces) in the mammalian extrastriate visual cortex. How birds solve face and object representation without a neocortex is a long-standing problem in evolutionary neuroscience, though multiple lines of evidence suggest that these abilities arise from circuitry fundamentally similar to the extrastriate visual cortex. The aim of the present experiment was to determine whether birds also exhibit a categorical representation of the avian face-region in four visual forebrain structures of the tectofugal visual pathway: entopallium (ENTO), mesopallium ventrolaterale (MVL), nidopallium frontolaterale (NFL), and area temporo-parieto-occipitalis (TPO).