Facial recognition itself comes from the brain's ability to recognize a facial “template” of eyes, nose, and mouth in specific relation to each other. This information is processed in the fusiform face area (FFA), where it is then sent through other brain structures like the amygdala to determine the face’s emotional importance. We know the FFA is responsible for facial processing because of the increased event-related potentials (ERPs) localized in the middle and posterior fusiform gyri. N170 responses in adults are larger when viewing faces than any other type of stimuli, even as early as 4.5 months old (Conte et. al., 2020).
A 2014 study, Face recognition as a predictor of social cognitive ability: Effects of emotion and race on face processing, found a positive correlation between emotional intelligence and performance on a facial recognition task (Chen, 2014). This suggests that one of the most important indicators of social interactions is recognizing the other’s facial expressions. Facial expression can communicate as much as the words a person says, from the intention of the words to nonverbal responses. Cues like eyebrow raises can mean skepticism when paired with a frown or humor when paired with a grin. When confronted with someone in pain, someone with a neurotypical brain will most likely have a reflexive, empathetic expression of pain as well (Frith, 2009). This response is commonly known as simulation, or the mediation of nonverbal communication. Theoretically, this involves tracts of neurons called the mirror neuron system (MNS). The MNS maps other’s actions onto our own motor cortex and overlays multiple regions of the brain, one of which was recently found to be the fusiform gyrus (Dhar & Arora, 2020). There has been shown to be significant activity in the FFA when viewing and/or imitating the facial expressions of others (Montgomery & Haxby, 2008). A test found to be reliable to monitor mirror neurons (using transcranial magnetic stimulation) was used in conjunction with tasks used to measure both static and dynamic facial emotion processing. The researchers discovered that a marker of MNS activity correlated with performance on the facial emotional processing task. While in broader terms there was no correlation between mirror neuron activation and facial processing, there was significant activation when confronted with static stimuli. The researchers theorize that mirror neurons may be more focused on the variation of facial expressions and the underlying motor functions that stimulate mirror neuron activation (Enticott et. al., 2008).
The MNS allows us to process others’ emotions as our own, so we can easily relate to them and empathize, and a hallmark of Autism Spectrum Disorder (ASD) is difficulty with processing social interactions. Since faces play such an important role in these interactions, it is reasonable to assume that those with Autism have trouble processing faces and emotions. This claim is backed by research done at Penn State, compiled by Kristie Auman-Bower. In 112 studies with over 5,000 participants, over 80% of participants on the Autism spectrum performed worse than neurotypical participants on tasks involving face identity processing. Because these findings did not vary significantly with sex, age, race, or IQ, it was determined to be a core deficit. This data compilation has backing from Dr. Maggie Guy’s research, which looks more at the physical happenings within an Autistic brain when it processes faces. Guy’s study looked at infants with precursors to ASD to explore differences in facial processing between them and neurotypical infants. She showed that the N290 ERP was still present and activated when an at-risk infant observed a facial stimulus. A child with Fragile X Syndrome (a known precursor to ASD) can still recognize a face. Later in life, if the child develops ASD, emotional recognition and facial recognition must have different routes of processing.
It is theorized that deficiencies in the mirror neuron system may be responsible. In V. S. Ramachandran’s book, The Tell-Tale Brain, he examines others’ research and expands on the possibilities of research with mirror neurons. He also warns that the MNS is not a catchall structure for any unknown within the brain. However, it is very probable that those on the Autism spectrum have problems relating to the emotions of others because they cannot process it themselves due to mirror neuron deficits. The suppression of Mu-waves, the most likely key to recognizing mirror neuron activation, does not happen as often in those with Autism. Mu-wave suppression strongly correlates with motor cortex activation when we either perform a task ourselves and/or observe another perform a task. In those on the Autism spectrum, Mu-waves are only suppressed when the person themselves performs a task. This lack of suppression translates to facial expressions as well, showing that those with ASD do not process others’ facial expressions of emotion as well as someone with a neurotypical brain. While deficiencies in mirror neurons cannot explain every symptom of ASD, mirror neurons and research around them are a promising start to understanding the specific ASD symptom of trouble with social interactions.
References
Auman-Bauer,
K., (2020, October 26). People with
autism may have large deficits in facial recognition. Penn State
University. Retrieved from https://news.psu.edu/story/636702/2020/10/26/research/people-autism-may-have-large-deficits-facial-recognition.
Chen,
Jiaqing. (2014). Face recognition as a predictor of social cognitive ability:
Effects of emotion and race on face processing. Asian Journal Of Social Psychology. 17. 10.1111/ajsp.12041.
Conte, S., Richards,
J. E., Guy, M. W., Xie, W., & Roberts, J. E. (2020, February 8). Face-sensitive brain responses in the first
year of life. NeuroImage. Retrieved from https://www.sciencedirect.com/science/article/pii/S1053811920300896?via%3Dihub.
Dhar,
Dipak & Arora, Ritik. (2020). The Mystery behind “Yawning”: A Physiological
Insight. Journal of Health and Allied
Sciences NU. 10. 10.1055/s-0040-1714196.
Enticott, P. G.,
Johnston, P. J., Herring, S. E., Hoy, K. E., & Fitzgerald, P. B. (2008, May
8). Mirror neuron activation is associated with facial emotion processing. Neuropsychologia. Retrieved October 22,
2021, from https://www.sciencedirect.com/science/article/pii/S0028393208001905?via%3Dihub.
Frith
C. (2009). Role of facial expressions in social interactions. Philosophical transactions of the Royal
Society of London. Series B, Biological sciences, 364(1535), 3453–3458. https://doi.org/10.1098/rstb.2009.0142
Montgomery,
K., Haxby, J., Mirror Neuron System Differentially Activated by Facial
Expressions and Social Hand Gestures: A Functional Magnetic Resonance Imaging
Study. J Cogn Neurosci 2008; 20 (10):
1866–1877. doi: https://doi.org/10.1162/jocn.2008.20127
Ramachandran, V. S.
(2012). The Tell-Tale Brain: A
Neuroscientist's Quest for What Makes Us Human. Windmill.
No comments:
Post a Comment