the brain every time you think feel or perform a multitude of unconscious processes the 100 billion neurons in your skull conduct electrical signals to communicate and carry messages between them ultimately creating well you and everything you do it’s the most complex essential and identifiable organ in the body acting as the center of the nervous system in all vertebrates but what if how you think and feel isn’t just controlled by the brain and central nervous system but in fact a second brain that you didn’t know about the brain uses the vagus nerve to connect and communicate with many parts of the body including the vocal cords heart lungs and most of the digestive tract it also uses this nerve to convey fight-or-flight messages to the body which explains why you might experience a cracking voice racing heart shortness of breath and a knot in your stomach when you’re really stressed or nervous but while this extensive network is constantly sending signals from the brain to your body scientists have noted that 80 to 90 percent of the nerve fibers in the enteric nervous system are actually going from the gut to the brain in fact the enteric nervous system which is an extensive mesh-like network of neurons that controls your entire digestive tract from the esophagus to the anus doesn’t even require the brain at all when the vagus nerve is severed the enteric nervous system is capable of organizing and initiating its own reflexes for digestion because it has such a complex collection of neurons it is your second brain and controls you far more than you realize from an evolutionary perspective before modern food safety protocols our biggest choices were about eating is it safe will it make me sick will it give me energy this is why we need a direct line of communication between the gut and the brain for example fat and sugar are good sources of fuel for the body so we’ve evolved mechanisms to notify the brain to release the feel-good neurotransmitter dopamine when we eat foods high in fats and sugars which make us continually seek them out but the enteric nervous system becomes even more interesting when you realize that the microbes in your gut actually produce over 50% of the dopamine found in your body and 90% of the serotonin to neurotransmitters that drastically affect your mood happy is and pleasure and these microbes can manipulate your cravings and eating behaviors for their own survival your diet affects which bacteria thrive but as a result the flourishing bacteria in your gut can then send signals to the brain via the vagus nerve to tell you to keep eating the foods that they love this is why some scientists have suggested that treatment with probiotics or fecal transplants could be an effective therapy for overeating by getting rid of certain bacteria that generate intense cravings for high fat and high sugar foods in fact current research is pointing to a gut with healthy microbiome as a strong predictor of emotional and mental health mice raised in sterile environments where no bacteria could colonize their gut exhibit social traits similar to those seen in humans on the autism spectrum when researchers studied their brains they also found significant changes in the levels of serotonin and specific proteins related to learning and memory formation but after feeding the mice with specific probiotics to help cultivate healthy microbiomes the symptoms were alleviated their gut controlled their behavior a 30-day study comparing people who ate probiotic yogurt found a decrease in the levels of anxiety and depression compared to people who consumed milk with no bacteria and another study found that mice fed a specific bacteria had less stress-related hormones in their blood and performed better on tests of learning and memory but when researchers severed the vagus nerve all of these improvements disappeared again their guts were in control of their emotion studies have even shown that stimulating the vagus nerve at different frequencies by implanting a small pacemaker can help patients with treatment-resistant depression by mimicking vagal nerve activity like a person with a healthy gut and the essential role of the gut doesn’t end there given that large social groups increase the potential for one’s genes being passed on for both us and our bacteria researchers now believe that the function of the microbiome is partly to promote pro-social behaviors healthy gut bacteria can lead to a higher resilience of negative emotions from others which makes you more forgiving and better at fostering strong social connections ultimately improving your shot at reproduction all thanks to your second brain special thanks to audible for supporting this episode to give you a free 30-day trial at audible.com komm slash ASAP this week we wanted to recommend the book how not to be wrong the power of mathematical thinking which helped us create our previous episode are good-looking people jerks it’s an awesome read you can get a free 30-day trial at audible.com slash ASAP and choose from a massive selection we love them as they’re great when you’re on the go and subscribe for more weekly science videos Video source: https://www.youtube.com/watch?v=T3Ftj5E90tY
