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The Science Behind A Baby’s Blinks

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If you’ve ever taken the time to watch a baby’s face you might have noticed that they don’t blink as often as we think is normal for adults. In fact, you might notice that they only blink a few times in one minute and some babies even only blink once a minute. In comparison, adults blink about 15 times in one minute. Why does this even matter though? Blinking is regulated by dopamine in the body and scientists are beginning to think that the slower blink rate is babies might have insights into the way that babies brains work.

Dopamine is a neurotransmitter that allows the brain cells to communicate. Dopamine levels have already been linked to different behaviors in patients and blinking rate is one of those. For instance, schizophrenia patients have a faster rate of blinking than the average adult and Parkinson’s patients have slower rates. Unfortunately, it’s not that cut and dry as dopamine also regulates and underlies many other functions in the body including control of movements and hormonal levels to learning and motivation. As more and more research is conducted, scientists are hopeful though that blinking rates can be an inexpensive and non-invasive method to roughly test a patient’s dopamine levels. To get there though, there are a few things that have to be researched and tested first.

 

Why Do We Blink?

To even begin answering the question of how blinking would help scientists predict dopamine levels, the reasons why we blink have to first be understood. In fact, there are three different types of blinking – involuntary blinking, reflexive blinking and voluntary blinking. Reflexive blinking occurs when we’re trying to protect our eyes from something that tries to get it, such as when you blink when you accidentally poke your eye. Voluntary blinking is the blinking you do when you think something is in your eye, for instance, and you blink voluntarily to try to get it out.

Scientists are mostly interested in the spontaneous blinking that we do and the research started a long time ago. In 1928, two researchers tried to study the blinking rate in adults to see what kinds of situations influenced the number of blinks. Erik Ponder and W.P. Kennedy devised a mechanical apparatus, consisting of a silk string, a piece of wood and spring connected to an electrical circuit. Every time the patient blinked, the circuit was interrupted and a change was recorded. This crude mechanism was able to point to a few interesting factors when it came to involuntary blinking though.

First, each person’s blinking rate was like clockwork as long as the conditions were kept the same. Dark and well-lit rooms didn’t change the blink rate for the participants and neither did dry or humid conditions. Blind participants had the same average blink rate as seeing participants and even anesthetizing the surface of the eye didn’t change the rate at which participants spontaneously blinked. What did change the rate was changes in the ‘mental tension’ of the participants. For instance, those that were stressed, angry or excited tended to blink faster or more often, such as witnesses on the stand being cross-examined.

The findings of Ponder and Kennedy have largely influenced the modern day studies of blinking. The two scientists proposed that there was a ‘blinking center’ in the brain and that blinking was akin to fidgeting or wringing of the hands, an act that was used by the body to momentarily relieve tension or pressure felt. Modern studies seem to correlate that; one hypothesis is that blinking gives the brain a moment of rest and a study published in 2012 in the journal Proceedings of the National Academy of Sciences found that brain activity spikes in the ‘default mode network’ when people blink. That network is comprised of a number of brain regions that are active when we are awake but resting and our brain disengages from the outside world, such as in daydreaming instances.

 

Blinking and Dopamine Connection

How does all of this connect dopamine to blinking? Unfortunately, certain research is still out on that question. Some studies seem to suggest that there is a link while others vehemently deny it. One study in 2017 in the journal of Society for Neuroscience states that evidence for a connection is uncertain and incomplete and that the studies that do suppose to support it have only tested nonhuman animals. The study then proceeded to study the connection in healthy, human adults. Their study found no relation between spontaneous eye blink rate and dopamine receptor availability and the eye blink rate also did not change in response to dopamine stimulation with certain pharmaceuticals.

The dopamine connection to blinking might not be definitely determined yet, but that doesn’t mean that scientists aren’t still looking into it. Some researchers have hypothesized that the decreased blink rate in infants is due to their underdeveloped dopamine system, which again brings us back to dopamine influencing the spontaneous eye blink rate. If dopamine and blink rate are connected, it would be a great tool for determining individual differences in personality, cognitive abilities and the risk for dopamine-related conditions such as ADHD.

 

Other Blinking Theories

There are other reasons being circulated as to why we blink, most of them having to do with environment or the things we do. Of course, one of the most circulated theories is that we blink to keep our eyes lubricated. Babies have smaller eyes and thus they don’t need to be as often lubricated – but this brings up the question if babies produce as much lubricants as adults do; the only way that this theory would be more believable. Another idea is that infants keep their eyes open longer because they have more to take in visually. To get all the visual information they need, babies blink less than the average adult.

Visually demanding activities also make adults blink less, a phenomenon called computer vision syndrome makes adults reduce their blinking rate and can also lead to dry eyes (another reason that some think blinking is for lubricating the eyes). This same idea applies to why babies keep their eyes open longer and don’t blink as much. Unfortunately, there’s no definitive answer yet to this question and more research is still needed to determine as to why people spontaneously blink.

 

Conclusion

Babies have brought up an interesting topic recently for researchers – and the question of why people blink and what causes them to blink more or less has been studied for many years now. As far back as 1928, two researchers made it their mission to study the blinking patterns of adults and found that environment, lubrication and even blindness didn’t make a change in how often people blink. Despite their findings, research is still being conducted as to the causes of spontaneous blinking and, recently, dopamine connections have come up in studies as to being the reason for the blinking rate. Unfortunately, scientists don’t agree on this connection as some studies have disproved this and others have insisted on the connection. There is still much research to be done but the fact remains that babies do blink slower and less often than adults do – and finding the reason why may just have real insight to the human brain.

 

References:

www.ncbi.nlm.nih.gov

www.ncbi.nlm.nih.gov

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