Although we’ve talked at length about sensory data transmission, chemical synapses handle much more than messages about what we’re seeing, smelling, touching, or tasting. In fact, they’re involved in just about every physical process that keeps us alive. From muscle movement to organ function to countless other physiological activities we can’t detect without advanced lab equipment, roughly 100 different neurotransmitters are keeping our systems vital and operating (hopefully) normally. The gaps of our synaptic clefts harbor both opportunities and dangers. Whether in the pre-synaptic axon, in the post-synaptic dendrite, or in/around the cleft itself, even a slight variation from the norm can produce serious effects. When your body doesn’t produce enough of the neurotransmitter dopamine, for example, you can develop Parkinson’s Disease, with its slowness, trouble walking, rigidity and shaking, as well as depression, anxiety, and problems with sleep and emotions. Too much of the neurotransmitter serotonin in your system can result in serotonin syndrome, which can be toxic, even fatal. Dilated pupils, tremor, sweating and high body temperature (as high as 106°F), possible seizures and irregular heartbeat are just some of the symptoms associated with a condition directly related to an over-accumulation of just one of the many neurotransmitters in your body. Socrates’ chemical synapses made his death possible, when the poison hemlock he drank blocked the receptors at the neuromuscular junction. His muscles were progressively paralyzed, including his respiratory muscles, which cut off oxygen to his heart and brain.
Of course, when our chemical synapses are releasing and receiving their messages in “normal” ways, we’re not only able to keep functioning, but we’re able to grow and adapt. Our heart beats at a steady rate. Our liver and kidneys clean out waste. Our lungs take in and distribute oxygen. We can think clearly, we can get up and get ready for work, and we can just get on with our lives. Our nervous systems are plastic, or able to change in important ways. We learn. We make connections. And the amounts and types of neurotransmitters our neurons release change in response to external stimuli (such as longer or shorter daylight hours). Everything… just works the way we regularly expect it to. But behind the scenes, at levels so microscopic we couldn’t detect until the past hundred years, an incredibly complex series of intricate communications is firing away, myriad times, each and every minute of our lives. Without the interrelated functions of neurotransmitter release, travel, reception, synthesis, and reuptake (and possibly other interactions we haven’t even discovered yet), none of that would be possible.
What’s more, we wouldn’t have the variety of experiences that come from different behaviors of different neurotransmitters. Imagine a world without the appetite and emotional variations of serotonin… the arousal, motivation, and rewards of dopamine… the rush of epinephrine (adrenaline)… or the 100 or so other types of messengers that transmit signals through our systems. Our emotions would likely be very different than what we’re used to – if they’d exist at all. Euphoria, anticipation, stress responses, sadness, depression, anger, pleasure, wouldn’t be anything like they are now, if the neurotransmitters which support to them didn’t need to exist. We also probably wouldn’t have the variety of behaviors that arise from the unique biochemistry of each individual. Passions and motivations might be unrecognizable to us, if they existed at all. The psychoactive drugs we have now would not work – because they act directly on our neurotransmitters. At the same time, we might not even need those drugs, because there’d be no neurochemistry (or a very different kind) at work in our bodies and brains. And without the separation of our synaptic clefts, there’d be no reason for those neurotransmitters to exist.
Who can say how different our experience would be, if our bodies dealt only with electrical signals? Would we “short out” from the unimpeded electrical current? Would things work better? Would they work worse? Would everything go faster, but with less nuance? Would we need more electrical signals to account for variations in quality we’d lose without those chemical connections? Would we even care about the variations? Would we miss all the downsides of neurotransmitters run amok? Or would our lives be so qualitatively different that we’d never even realize we needed those little chemical messengers? It’s impossible to know. At the same time, it’s fair to say the entire experience of life would probably be less varied, less rich, and a lot less interesting in terms of human experience. We might have fewer lows. But then we might also have to sacrifice our highs. Would we want that? The whole point of many popular psychoactive substances, is getting high. And many individuals taking medications which modulate their neurotransmitters discontinue use precisely because they miss the “upsides” of their individual biochemistry. A lot of us don’t want to sacrifice the highs because of the lows, even if it comes at a steep price to ourselves and our friends and family.
Without the separations of synaptic clefts would we have neurotransmitters at all? For that matter, who can say if human life would even be possible, if we had no distance for them to cross? Those packets of chemical goodness aren’t just for entertainment value – they actually keep our intricate systems running – physically, mentally, emotionally, and spiritually. All because our systems are innately separate.
Just as synaptic distance is a critical component of our living systems, larger distances we can measure without special equipment serve us well. In fact, we’d lose a real advantage, if our sensory signals didn’t have to travel as far as several feet. Say, you’re warming some milk for a relaxing drink before you go to bed. You reach out to take a pan off the stove, pleased with yourself that you remembered to remove it from the heat before the liquid burned. Suddenly, you realize that the handle is hot, and you quickly set it down on a nearby trivet. If there were no distance between sensory detection and the brain, there’d be less time for you to be pleased with yourself (however briefly), before you realize the handle is hot. After you’ve poured your drink into a mug, you’d also have less time to relish an experience, as it fills your body with a sense of well-being, because an electrical trip from your tongue to cerebral cortex would be nearly instantaneous – and the return trip to the reacting muscles that make you swallow would be just as quick. The end result might be a highly efficient process of drinking warm milk. But could you enjoy it? Without chemical interactions to boost the signal along the way, the end message might be less complete than its chemical equivalent. And without the time delay that literally lets you make sense of the experience, how could you?
Electrical “efficiency” would actually be a profound loss for us as living, breathing, experiencing human beings. To never be able to savor the taste of food, to never be able to enjoy physical contact with another human being, to never have the pleasure of the dawning realization that someone is trying to help – not hurt – us. If there were no physical, temporal, or conceptual separation between “us” and our surroundings, we’d be little more than automatons propelled by base, unthinking reaction. Our humanity needs that distance between when we first engage with something or someone, till when the data reaches our brain for our mind to make sense of it – literally and figuratively. We need that delay to find it meaningful and let it change our lives – for better or for worse.