Cinema Peer Review: Neuroscientist Heather McKellar on ‘Inside Out’

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Disney-Pixar’s new movie, Inside Out, combines beautiful animation, creative storytelling, and a touch of neuroscience to explain the “voices” inside 11 year-old Riley’s head as she navigates a difficult period in her life. I first saw the movie in preparation for a screening as part of this year’s World Science Festival. I knew I would have to explain to an audience of families that much of the way the brain is represented is false, at least in terms of neurobiology. I left the theater crying because the movie was so good at touching my emotions, but also completely nervous about what I would say about how emotions color our memories and direct our behavior. As I thought about how to explain what is known about the cellular basis of memory, the role of the emotional brain area, and the importance of sleep, I realized there are basic principles behind some of the neurobiology in the story that are correct and could get kids and families excited about the brain.

Going Head to Head: Riley’s Headquarters versus the Actual Brain

INSIDE OUTHalf the movie focuses on the storyline of Joy (Amy Poehler), Sadness (Phyllis Smith), Anger (Lewis Black), Fear (Bill Hader), and Disgust (Mindy Kaling)—a quintet of wonderfully charming emotions/characters that drive Riley’s behavior. They reside in the command center—aka headquarters—of Riley’s brain and monitor her reactions to the world, while affecting each memory that is made.

In your brain the regions that are considered your emotional center are collectively called the amygdala nuclei. They are two almond-shaped structures located in the deep brain, one on the left and one on the right side. While the amygdala modulates our behavior and emotional memory formation, it is not the only driving force of our actions. Oparkinson1ur prefrontal cortex, the area right behind the forehead, plays an important role in the regulation of emotions, decision-making, planning, and abstract thought. It is our control center, but it is also one of the last regions of our brain to fully mature.

For children’s brains, in fact, emotions can have an especially strong influence, since their prefrontal cortex is still developing and they have less impulse control. While emotions are not at the control console alone as portrayed in the movie, they do indeed shape how we perceive a situation and affect what we will remember.

A Neuroscientist’s Emotional Rescue

In the movie memories are portrayed as bowling balls colored by a specific emotion that roll into the command center with each new life experience. While the bowling alley is an interesting visual, the actual physical changes that occur in our brain are more like buds forming on a tree branch. The connections between the 86 billion neurons in our brain occur at structures called synapses and many of these form at little protrusions known as spines. We know that the more a pair of neurons communicates, the connections strengthen and the spines enlarge and become more stable. This change or plasticity, as scientists term it, is thought to be how the memory is stored.

Interestingly, even in long-term memory, our brain remains malleable. Our long-term memories are not hard balls that can be replayed like a never-changing YouTube video. Each time we recall a memory, we change it in a process called reconsolidation. So unlike encapsulating each new experience into a solid bowling ball that is stored as is until we want or need to recall it, our brain is ever changing at the cellular level, both at the time the memory is made and even during recollection.

How Memories Are Stored: Like buds forming on a tree branch, the connections between the billions of neurons in our brain occur at synapses, many of which form at small protrusions called dendritic spines. The more a neuron pair communicates, the stronger the connections get and the larger and more stable the spines become. (See animation.) This change (or plasticity) is thought to be how the memory is stored.

Dream on

Finally, in the movie, sleep is when Riley’s short-term memories are sent to long-term storage and when the “dream factory” gets to work replaying all the day’s events. Scientists are now finding evidence that these two processes are closely linked. (This connection was discussed at another event in this year’s Festival in celebration of Alan Alda’s Flame Challenge. You can watch experts discuss how important sleep is for everything from growth to learning and memory to brain health.)

As is portrayed in the movie, sleep is the period when memories of the day’s events are sent to deeper storage—what we term memory consolidation—and is critical for learning. This is true for humans, rats, and even fruit flies! Wenbiao Gan, a scientist and colleague at the NYU Langone Medical Center where I work, has shown that sleep is essential for the physical changes in the brain spines of a rat that is learning a new task. So indeed, we need sleep to learn and remember just as much as Riley does.

Watching the Life of Riley

INSIDE OUTMore broadly, Inside Out is an incredibly beautiful visual and narrative treat with a captivating story and wonderful central characters. Riley is an endearing little girl facing real-life struggles growing up as her brain changes with the world around her. The emotions, led by Joy, develop in complexity as Riley matures in a way that seems both touching and true to life. So, even if the scientific metaphor is sometimes off, it is obvious that the creators have taken great pains to create a very human story around the ever-evolving theories of psychology and neurobiology.

My final thought comes from a question posed by an audience member during the World Science Festival event. A teenage boy who had waited patiently for me to call on him asked in a clear voice, “Will a film like this that focuses so much on emotions help someone like me that has autism and so problems with my own emotions?” I hope so. I believe that more films that take science seriously will open up conversations about what we know and what we are still learning about that important organ inside our head.

Inside Out opens in theatres on Friday, June 19.

Overall: 3 out of 5 neurons.

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AasHi RiotZz
AasHi RiotZz

AasHi RiotZz a/c refrEsheD ♡ 3.1K uNfriendeD :p 1K DP


I'm really excited to see this! Thank you, Dr. McKellar, for your review and explanation. 

Deanna Medeiros
Deanna Medeiros

I saw this today. All the adults were crying , the kids were amused. I'd give it at least 4 out of 5 neurons!