The default mode network (DMN) in humans is characterized by strong connections among the medial prefrontal cortex, posterior parietal cortex, and posterior cingulate cortex. In common marmosets, however, the dorsolateral prefrontal cortex shows robust functional and anatomical connections with the posterior DMN regions, while the medial prefrontal cortex has weak connections. This pattern differs markedly from the human DMN, suggesting that the medial prefrontal cortex may support brain functions that are more developed in humans than in other primates.
Multistable perception—where sensory ambiguity causes spontaneous alternations between two or more perceptual interpretations—occurs across many animal species. This review covers research on visual perceptual rivalry in insects, fish, reptiles, and primates, highlighting binocular rivalry and the Necker cube as examples. Common behavioral indicators of perceptual alternation appear across species. The comparative approach offers insights into how brains suppress conflicting sensory signals and generate shifts in perceptual dominance, suggesting that ambiguous sensation is a fundamental problem that has shaped brain evolution.