Our brain is never really at rest. When it is not busy with a specific task, it can daydream or ruminate, depending on our mood, but it never stops being active. This is what neuroscientists have uncovered by discovering the functioning of its so-called “default” network, which is activated in a way that is opposite to the executive network that manages our high-level cognitive processes. Here are some figures to make you… contemplate more!
More than 6,000. That’s the number of thoughts we could have on average during a day. Canadian researchers were able to arrive at this figure using a new method to detect the transition from one thought to another. (Tseng and Poppenk, 2020)
46,9 %. This is the proportion of time we spend with “the head in the clouds” during a day. Our brain is then in “default network” (DN) mode, the most important of the functional networks in the resting state, which is associated with our introspective mental activities. This is the mode our brain is in when we are daydreaming, but also when we are ruminating… (Killingsworth and Gilbert, 2010)
One-tenth of a second. That’s how little time it takes for our brain’s default network (DN) to disconnect or reconnect. This network works like a communicating vessel with our executive network. As soon as an external object solicits our attention, the DN disconnects while the executive network takes over. As soon as the object is found, the DN reconnects. (Jerbi, Lachaux et al., 2011)
20 %. This is the proportion of body energy that the brain consumes at “rest,” less than 5% more than when it is involved in a task. Remember that the brain represents only 2% of the total body mass. (Marcus Raichle quoted in Le Monde, 2013)