Week 4: Neurotransmitters
Another week, another topic. This time, we dove deeper into the specific chemical mechanisms that synaptic transmission operates on. We learned about different neurotransmitters, how they are produced and released by synapses, and how postsynaptic receptors react to their presence.
By this point in the course, it no longer comes off as a surprise that there’s great variety in the neurotransmitters involved in brain activity. It seems that at every level of brain activity, any particular mechanism is implemented in dozens of different ways that all accomplish the same basic task. According to some information online, more than 500 neurotransmitters have been identified in the human body.
Does the human nervous system really need such a large number of neurotransmitters to be able to function properly? If the number of neurotransmitters is proportional to the complexity of cognitive processing in the organism, that should imply that for less-intelligent animals, there should be fewer neurotransmitters. I wonder if there’s research on the number of transmitters present in, say, rat brains.
When it comes to the specifics of neurotransmission presented in the chapter of the week, I found the G-protein systems the most interesting, as they leave open possibilities for more significance than just basic pulse transmission between neurons. The book brings up the possibility of the cascading effects of G-protein systems potentially relating to memory via long-term changes in the chemical makeup of neurons. Could these slow-burn effects also relate to neural responses that persist for a while, such as emotional reactions?
As always, when new neural systems are introduced, one wonders how they could be externally affected and to what effect. In this case, the diversity of neurotransmitters brings with it the possibility of selectively inhibiting activity applying a particular transmitter in neuron population. By blocking the receptors responding to a specific neurotransmitter, one could disable synapses operating with that transmitter while leaving other synapses untouched. I suspect anesthesia works this way, blocking synaptic transmission in sensory neurons to prevent pain signals from passing through.
Basic neurochemistry continues being simultaneously unexpectedly simple on a macroscopic level, yet very diverse and detailed in the microscopic level. This is quite possibly the worst combination for attempting to understand brain function based on how individual neurons work and interact. It is difficult to fathom how such simple systems could produce such nuanced brain activity, yet a full understanding of the details of these simple systems is elusive due to the high diversity. It is no wonder that understanding how brains work has proven itself a tough nut to crack even for the brightest of minds.