Some of us can socialize all day long without tiring (extroverts), while others of us reach a socialization limit and thereafter need down time (introverts). In his book Projections, Karl Deisseroth discusses how the extroversion-introversion scale might relate to the autism spectrum, positing that those on the spectrum may experience something similar to extreme introversion. The neuroscientific explanation he gives for why this might be is fascinating.
Deisseroth’s patient Charles, who is on the autism spectrum, cannot maintain eye contact without feeling overwhelmed. Why not? Deisseroth uses research studies from the field of optogenetics to search for answers (bear with this technical explanation for a moment):
“In our initial excitation/inhibition paper in 2011, we . . . had reported that causing high excitability of prefrontal excitatory cells (an intervention that elicited social deficits) actually did reduce the information-carrying capacity of the cells themselves, in a way that we could measure precisely, in bits per second. Thus, the very same kind of altered excitation/inhibition balance that disrupted social interaction was also making it harder for brain cells to transmit data at high information rates—corroborating what Charles had described for us in his account that the information coming in through eye contact overloads the rest.”
That was a bit complex, so here’s a simpler version. There are cells in the brain that can get excited, and when they do, a mouse (and also, presumably, a human) has a diminished ability to engage socially with others. When the cells get excited they also have a diminished information-processing ability. If this can be applied to autism, then a person who experiences a diminished social capacity might also experience a diminished ability to process information. Hence a person with autism might feel overwhelmed by all the information obtainable from looking into another person’s eyes.
Deisseroth compares the autistic person’s plight to how he felt when, during the pandemic, he had to perform the job of emergency psychiatrist over the phone. Cut off from all of the information obtainable from being in the same room with another person, he was forced to pick up signals from the auditory sense only, through the distortions of a phone line. Like a person on the spectrum, he had a reduced carrying capacity which constrained, but did not entirely prohibit, his ability to communicate.
Another interesting feature of this chapter is that Deisseroth compares Charles, his autistic patient, to another patient of his, Aynur, whose easy extroversion is off the charts. He explains that her brain must have a large carrying capacity for processing the vast amount of information needed to successfully navigate a social environment, while Charles’ carrying capacity is limited, as most people’s are, particularly introverts and people on the spectrum.
Deisseroth is not saying that autism and introversion are the same thing. Rather, he is saying that there’s something about the brain’s functionality that seems to be similar for people on the spectrum and introverts (and the Venn-diagram intersection of the two).
What is your carrying capacity for social interactions? Mine is limited to about 4 hours at a stretch. . . .