The default mode network is one of several brain networks active when a subject is at rest. It is found not only in humans but in monkeys and rats (see (Jessica Hamzelou, “Rat reflections give pause for thought”, New Scientist 8 Oct 2011:14). Yihong Yang and Hanbing Lu at the National Institute on Drug Abuse, in a study not yet published, have found evidence for a default mode network in rats. In humans the default mode network is associated with “functions of a self-referential nature” (Sheline, Barch et al 2008)—reflection or passive introspection. Activity in this network is inhibited during cognitive tasks (Greicius et al 2002).
Mantini, Gerits et al (J. Neuroscience 31(36):12954–12962, 7 Sep 2011) show that areas in the brain functionally similar to those involved in the human default mode exhibit similar patterns of activation. They conclude:
The present results suggest that, like humans, monkeys default to consistent sets of processes when left in undirected states. It is tantalizing to infer that monkeys engage in forms of spontaneous cognition detached from the external environment during idle moments. The observation that the anatomy of the DMN in monkeys includes heteromodal association areas and not sensory regions supports this speculative possibility.
They note that monkeys lack language “and therefore certain forms of self-referential processing” (citing R. Passingham, “How good is the macaque monkey model of the human brain?” Current opinion in neurobiology 19(2009):6–11). Nevertheless they exhibit “protoforms” of human capacities: and so—perhaps!—something akin to reflection, daydreaming. Another distinction goes by the wayside…
Recent Comments