A Day in the Life of a Brain

“Sumarri, time to get up!” Hearing her mother’s call, Sumarri rubs her eyes and then stretches her arms, awakening to a new day. Inside Sumarri’s head, her auditory cortex activates as she hears and understands her mother’s message. Even before she opens her eyes, she knows that it is daytime because of her “internal clock” or circadian rhythm. Her hypothalamus has adjusted levels of the hormone melatonin, which helps keep her internal clock regular, making her sleepy at nighttime and awake during the day. If we didn’t have an internal clock, we might sleep all day and be awake all night!

Sumarri begins her day with a healthy breakfast. She smells apple and cinnamon oatmeal and her mouth begins to water. Although it feels like her hunger comes from her tummy, her brain is hungry first! The scent of Sumarri’s breakfast stimulates an area of her brain called the olfactory bulb. If she couldn’t smell her breakfast, it would taste bland. You can’t taste food very well unless you can smell it. Smell is the most powerful of the body’s five senses; sensors in the nasal cavity send scent messages directly to the olfactory bulb. Scents can also evoke emotional responses—sometimes very strong ones—because scent signals can also pass through the amygdala, the brain’s emotion center. The smell of Sumarri’s favorite breakfast makes her happy. Inside Sumarri’s brain stem, the hypothalamus controls her body’s appetite. The brain stem also regulates other basic survival functions, such as breathing, heart rate, and body temperature. Luckily for us, this all happens automatically. Imagine what would happen if we forgot to tell our hearts to beat!

In the classroom, Sumarri raises her hand and answers a question. “That’s correct, Sumarri! Well done! Here’s a gold star for you,” her teacher responds. Sumarri beams proudly. As Sumarri listens to her teacher, her auditory cortex activates. To comprehend the question, many areas throughout her frontal cortex are activated as she processes the incoming information, and compares it to what she already knows. As she recalls the right answer and says the answer aloud, the frontal cortex, where her executive functions—those responsible for higher thinking—and the motor cortex, which is one of the regions that processes movement, are active. Learning is a complex activity. Feedback and motivation help change the brain in ways that reinforce what is being taught. Sumarri is fortunate to be going to school in a rich and rewarding learning environment.

Art is one of Sumarri’s favorite subjects, and she looks forward to this part of her school day. While no particular part of the brain is associated with creativity, the primary visual and auditory cortices are specialized to detect patterns. As we are exposed to art and music, the complexity of the patterns that we recognize increases, so our ability to perceive light and sound actually improves. The more experience with the arts that we have, and the more we practice—whether we paint or play an instrument—the better we become!

Now it’s time for a small-group classroom activity. Sumarri forms a group with her two best friends, Nicole and Ashley. The amygdala, the brain’s emotion center, triggers Sumarri’s feelings for her friends. The inferior temporal cortex is specialized for face and expression recognition. By matching faces and facial expressions with previous experience, Sumarri recognizes friends and understands their intentions and feelings. Just imagine what would happen if we couldn’t recognize our family and friends!

Every body needs exercise, and Sumarri loves ballet class. Regular exercise helps strengthen your heart, which supplies oxygen to your brain. Inside Sumarri’s head, the cerebellum monitors the relationship between her body and the physical world, helping her to balance and coordinate her movements. Her primary motor cortex and supplemental motor area allow her to raise her arms and bend her knees. As she watches her reflection in the mirror, her visual cortex activates. We think of memories as revolving around events or facts we have learned. But because the brain controls all of our movements, even when we aren’t exercising, it also remembers those movements in a form of body memory. Body memories, like learning to ride a bike, stay with us forever. When Sumarri learns fifth position, she’ll never forget.

After dinner, it’s time for homework: reading a short story. As Sumarri looks at a printed word, just like you are right now, the electrical impulses representing the word travel through her visual system to the primary visual cortex, where letter-recognition occurs. Next, areas in the parietal and temporal lobes merge the letters and recognize that those letters form a word. In the temporal lobe and in Broca’s area, a sound is associated with the word. Even though Sumarri reads silently to herself, the areas of her brain that are associated with processing sound are as active as they would be if someone were reading the story aloud to her. In Wernicke’s area of the temporal lobe, a meaning is associated with the word. Finally, the angular gyrus in the parietal lobe synthesizes both the sound and the meaning of the word, turning words on a page into ideas in Sumarri’s head.

It’s been a full day, and Sumarri falls asleep as soon as her head hits the pillow. The sleep cycle contains five distinct phases, one of which is the Rapid Eye Movement (REM) phase. If you could watch yourself sleep during a REM phase, you would see your eyelids move as your eyes fluttered beneath them! What do you think you are dreaming about? Most dreaming occurs during REM sleep, which begins with signals from an area at the base of the brain called the pons. While everyone dreams, some people don’t remember their dreams in the morning. While Sumarri sleeps, her hippocampus sorts through the events of her day. This region of her brain then binds the important details together and strengthens her memory of those events. What events do you think Sumarri will remember from her day?