Watching Humorous Movie Scenes Keeps the Brain Engaged

Researchers used Charlie Chaplin's movie to investigate the neural activity in the temporal lobe of the brain and its environment associated with humor processing.

The funniest sequences in the movie were associated with an increase in high-frequency gamma waves and a decrease in low-frequency waves in the anterior brain areas, suggests a new study published in the journal Neuropsychologia.

Humor is essential for easing interpersonal tensions, stress, physical and moral suffering, and even improving the body's immune response. Given this central role in our lives, it is desirable to understand the cognitive and brain mechanisms on which it is based ().

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‘Simultaneous activation of cognitive and emotional neural circuits in the brain elicits laughter even when the perception of a situation suddenly changes.’

Humans are particularly susceptible to the comedic powers of non-verbal humor – such as gesticulations, falls, unwarranted blows, or imitations. Physical comedy is the basis of slapstick, burlesque, clowning, and mime. It notably permeates the silent films of Charlie Chaplin, known for generating hilarity across cultures.

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To fill this gap in understanding, researchers analyzed intracerebral electrophysiological recordings, which make it possible to look at neuronal activity directly with a high spatial and temporal precision (at the millisecond scale) in several brain areas ().

Using Paris Brain Institute's CENIR neuroimaging platform, they studied thirteen epileptic patients who had been implanted with deep brain electrodes as part of a pre-surgical assessment of refractory epilepsy.

They asked the patients to watch a three-minute excerpt from Charlie Chaplin's Circus (1928) while their brain activity was measured live. Beforehand, the amusing nature (or not) of each sequence had been evaluated, frame by frame, by a group of healthy volunteers.

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Later, they compared the patients' neural activity recorded during the funniest scenes in the film with that recorded during the least funny scenes. These results indicate that high-frequency neural activity, which is seen in tasks that require a lot of cognitive engagement, such as work, is also a mark of humor appreciation.

Conversely, scenes that are not funny – such as transition sequences where the character moves from one place to another without doing anything – promote inattention and introspection... and a preponderance of low frequencies.

Temporal Lobe: the Neural Basis of Humour Processing

More importantly, this inverse relationship between high and low frequencies was observed in temporal lobe regions but not in others. It seems that humorous content is not processed in the same way throughout the cortex and depends on brain areas and functions.

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According to a dominant theory, the treatment of humor is based on two complementary mechanisms. First, the detection of an incongruous element of reality. Then, the emergence of a positive emotion related to this incongruity ().

What is funny would therefore be both unexpected and pleasant and involve two neural circuits: cognitive and emotional. These results support this theory, as we confirm the prominent role of the temporal lobe in the appreciation of humor.

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As the anterior parts of this area are involved in semantic memory, we can imagine that their activity is linked to the analysis of the scene and the detection of its incongruous content. Conversely, the activation of its posterior parts could correspond to understanding the unusual – and therefore amusing – aspect of certain social interactions.

Future studies will have to show the simultaneous activation of cognitive and emotional neural circuits to formally validate the theory of incongruity. Researchers will also need to look at other areas involved in cognition (such as the inferior frontal gyrus and anterior cingulate cortex) and emotions.

Finally, there can only be a generalization about the mechanisms of humor by studying other forms of it. Using longer videos, with more complex social interactions where jokes, irony, sarcasm, or references jokes are present, we can expand our understanding of this magnificent, uniquely human phenomenon that is derision.

References:

Neural Correlates of Humor Detection and Appreciation in Children - (https://www.jneurosci.org/content/32/5/1784)
The neural basis of humour comprehension and humour appreciation: The roles of the temporoparietal junction and superior frontal gyrus - (https://www.sciencedirect.com/science/article/abs/pii/S0028393215301901?via%3Dihub)
Intracranial study in humans: Neural spectral changes during watching comedy movie of Charlie Chaplin - (https://www.sciencedirect.com/science/article/abs/pii/S0028393223000921?via%3Dihub)

Source-Eurekalert