Picture this: you’ve had a long day and at last, you finally get a chance to re-read one of your favorite books. Naturally, your mind drifts and suddenly, it’s not the main character completing all the actions written on the page, but you. Why is that?
Neuroscientists previously conceptualized that during “restful” tasks such as daydreaming, mind wandering, and reflecting, the brain was inactive (Azarias et al. 2; Connors et al. 1909). However, recent research shows that this theory is incorrect; the brain actually consumes 20% of the body’s glucose (an important energy source for the body) and oxygen (necessary fuel to power all functions) during these restful states, reflecting that this is a relatively high proportion of resources being used while the body is not actively completing any tasks (Connors et al. 1909). This state of rest in the brain is called the Default Mode Network (DMN), which has an integral role in “episodic memory, emotional processing, and the construction of mental narratives” (Azarias et al. 2). To understand more, neuroscientists utilize functional magnetic resonance imaging (fMRI) to study the Blood Oxygen Level Dependent signal (BOLD) in different areas of the brain; if the fMRI reflects that the BOLD signal is higher in a certain section of the brain, this signifies that there are high levels of brain activity there (Raichle 438).
Studies show that reading activates different areas of the brain; for example, decoding written language utilizes the occipital cortex or the visual cortex where language is being read (Wehbe et al. 11). One study observed participants through fMRI and had them read different types of passages. After analyzing the fMRI results to see the location and frequency of participants’ brain activity, they conclude that fiction reading is an active proponent of the DMN because of how it stimulates the brain with both vivid environments read in the passages and about other people (Tamir et al. 221). Reading literature involves transporting readers to a different world, enabling them to also deeper understand character choices and the fictional atmosphere. Furthermore, when the brain is being used for tasks that do not require explicit attention (such as participating in a conversation or completing a manual task), the DMN activates, prompting individuals to imagine different scenarios that may happen in the future (Azarias et al. 5). So, every time you go to pick up a book or daydream, know that your brain is working much harder than you think it is.
References
Azarias, Felipe Rici, et al. “The Journey of the Default Mode Network: Development, Function, and Impact on Mental Health.” Biology, vol. 14, no. 4, Apr. 2025, p. 395. PubMed Central, https://doi.org/10.3390/biology14040395.
Connors, Barry, et al. Neuroscience: Exploring the Brain. Jones and Bartlett Learning, 2025.
Raichle, Marcus E. “The Brain’s Default Mode Network.” Annual Review of Neuroscience, vol. 38, no. Volume 38, 2015, July 2015, pp. 433–47. www.annualreviews.org, https://doi.org/10.1146/annurev-neuro-071013-014030.
Tamir, Diana I., et al. “Reading Fiction and Reading Minds: The Role of Simulation in the Default Network.” Social Cognitive and Affective Neuroscience, vol. 11, no. 2, Feb. 2016, pp. 215–24. Silverchair, https://doi.org/10.1093/scan/nsv114.
This is super interesting! I am interested to know more about reading and the default mode network. It seems to me that the act of reading fiction may function differently than imagining a story created from your own mind. Does the DMN become more active during restful states without external input, such as a book? Or would the consumption of literature elicit the same response despite the difference in thinking (creating the story entirely vs visualizing the story based on a preexisting plot)? I love this topic and especially the acknowledgement of how much glucose is consumed by the brain! We need to fuel our bodies properly to allow cognitive functions to thrive, even those that we may not be aware of, such as the default mode network.
ReplyDeleteThis is a fascinating topic! I love the connection between reading and daydreaming, and reflecting on what it means for the brain to be at "rest" in energetic terms. I can't help but wonder if disorder in the DMN might somehow be related to experiences of racing thoughts or overthinking.
ReplyDeleteThis is very cool! In the past couple of years, I have heard more discussion of the more resounding benefits of reading, which I have come to strongly believe in and advocate for. Such benefits include reading fiction to strengthen critical thinking and empathy. The neuroscience you include in this post helps explain how reading provides such impactful benefits.
ReplyDeleteThis is crazy interesting, Sam! As an avid reader myself, I very much do find myself in this exact scenario, so it's really cool to understand why this happens. Thanks for sharing!
ReplyDeleteLove this. Now I know where I spend most my time, in default mode. Besides reading Im sure my BOLD goes wild when I'm learning physiology too.
ReplyDelete