What are the neuronal and ontogenetic foundations of cerebral asymmetries? This question is deeply investigated in two avian model systems: chickens and pigeons. It is well known that the brains of these animals display physiological and anatomical left-right differences, which are related to hemispheric dominances for specific functions. In both species, asymmetrical light stimulation during embryonic development induces a dominance of the left hemisphere for visuomotor control. Nevertheless, the underlying structural asymmetries vary essentially between both species. In this recent paper, scientist from the biopsychology lab analyzed existent data on this rather puzzling phenomenon. They found evidence that although early asymmetric light stimulation is defining the dominant hemisphere for visuomotor tasks, the structural mechanisms mediating this dominance can differ between species. Furthermore, they found that environmental stimulation likely affects the balance between hemispheric-specific processing by lateralized interactions of bottom-up and top-down systems. These findings show how the interplay between environmental factors and genetically determined lateralizations can shape functional asymmetries during early development.

Manns, M., Ströckens, F. (2014). Functional and structural comparison of visual lateralization in birds - similar but still different. Front. Psychol., 5: 206.