Interhemispheric Switching Can Occur under a Wide Range of Conditions and Time Scales

The vertebrate brain is symmetrically organized, with two identical-looking cerebral hemispheres and a brainstem that contains identically named nuclei on both sides of the midline. However tempting it is to think of each brain half as a mirror image of its contralateral counterpart, this is an incorrect oversimplification. Careful anatomical comparison of select anatomical structures and their connections reveals asymmetries across sides [1]. These asymmetries are not limited to anatomical features but also include extensive functional differences between cerebral hemispheres [2]. The existence of asymmetries implies that the two hemispheres are not just two massively redundant networks, but rather functionally specialized entities that work synergistically to coordinate the behavior of the organism.