Neuroscience and Dualism: A Brief Look into the Mechanisms of Consciousness

Introduction

The mind-body problem is an idea that was presented by the French philosopher René Descartes in the 17th century. He highlights that there exists a distinction between the mind and the brain. Our brain exists in the physical world because it is composed of matter, and therefore possesses things like direction, height, depth, length, width, etc. While you may read that and think “Well no s*** Sherlock, thanks for that riveting piece of information”, the interesting claim that Descartes makes is that the existence of the mind is something that should not exist in our reality. Our consciousness has no direction, height, depth, length, or width, yet it still exists in a three-dimensional world. How do we know our consciousness exists? Because we exist. 

Portrait of René Descartes - French philosopher whose work detailed the metaphysics of consciousness.

What are the physical mechanisms that create consciousness despite it not existing in 3D space? We need brain activity to form our sense of self and perceive our environment, but what structures are used to pull off such a feat? In this article, we will look at some of the proposed systems that govern our sense of consciousness, as well as ways that our brain re-arranges itself for altered states of consciousness. 

Setting the Stage

There are many different definitions of consciousness and the state of being conscious. For our purposes, we are defining consciousness as the function of the mind that receives and processes information in a general sense, along with the help of your senses, judgment, imagination, memory, etc. (Vithoulkas and Muresanu, 2014). More simply, we can define consciousness as being aware. We are by no means trying to start a philosophical debate. This definition simplifies our understanding of consciousness and serves as a groundwork for the studies that we are going to discuss. 

Firstly, it should be noted that consciousness is a spectrum. Our awareness fluctuates due to a countless number of factors that change our perception of our environment. We’ve all experienced these changes throughout our lives—from having to actively recall facts for a test to being “unconscious” during surgeries; when you're focused on a video game to your average Friday night out as a college student.

Arousal (the state of being awake and aware of your surroundings) is a very primitive human characteristic that is essential for the notion of consciousness. Because of its primitive nature, many of the brain structures implicated in keeping us aware of our surroundings are located in the brainstem; the oldest part of our brain and develops the least complex structures. The brainstem is the home to many of the automatic structures that we take for granted, such as swallowing, eye movements, and even vomiting. One structure that is important for consciousness (but certainly not the only one) is the ascending reticular activating system (ARAS). Studies have shown that lesions of this area produce a comatose state, which is regarded as being “unconscious” (Edlow et al., 2012). The ARAS is just one piece of the very complicated puzzle that helps to explain how we as humans are conscious. 

Consciousness is such a hard thing to study in general. There are many reasons for this, which range from trouble defining the term to the immeasurable amount of subjectivity that is associated with it. Nonetheless, many brain functions are implicated, such as short-term memory and sensory information (information sent to the brain that tells you about your environment). Neuroscientists have “narrowed down” the hub of consciousness to the cerebral cortex, which is the outermost layer of our brain as a whole (Walling, 2000). Although many of us may not be satisfied with this answer, the complexity of the question necessitates a complex answer, and that may be all that we have for now. 

Some Brain Mechanisms for Changes in Consciousness

Although studying consciousness as a whole is challenging, what’s less challenging comes from the fact that throughout peoples’ lives, changes in awareness are easy to come across. Here are some ways in which consciousness can change. 

Neuroplasticity is the process of strengthening frequently-used neural connections and weakening lesser-used ones by physically rearranging the structure of nerve fibers. Synaptogenesis (the formation of new connections) occurs throughout our lives (especially during early development) and refines neural networks which allow us to perform tasks more effectively, with greater precision, and requiring less energy. The topic of synaptogenesis is important in the topic of consciousness because it influences what forms of stimuli we can actively be aware of. Multiple studies have shown that the loss of the visual system leads to the formation of newer pathways as a way to overcome this “visual limitation,” strengthening one's awareness of auditory cues. This process can also be seen after brain damage. Neuroplasticity allows for other parts of the brain to take over functions that were previously handled by damaged areas. In many ways, our brain’s natural ability to reconfigure neural networks alters the scope of our awareness (Silva et al., 2018). 

In a similar light, drugs can directly influence neural connections. If you have hippie friends, you may have heard them talk about “the mystical power of shrooms.” Before you immediately discredit them, consider that there may be some truth to what they are saying. Many hallucinogens such as psilocybin (“shrooms”) and ketamine, in addition to altering consciousness, have been found to induce spinogenesis, which is the formation of new dendritic spines on neurons (Shao et al., 2021; Wu et al., 2021). The formation of more spines leads to more connections between neurons, which is beneficial for a variety of things, ranging from enhanced learning to improved neuronal response. Most importantly, spinogenesis plays a direct role in the idea of neuroplasticity that we discussed above. 

Looking at psilocybin in particular, the mechanism of action is very interesting. Psilocybin is a 5-HT2A agonist. 5-HT is another name for serotonin, which is most notably recognized for its impact on mood. When psilocybin is active in the body, it leads to increased activation of these receptors, which in turn leads to more cortical activation in regions such as the prefrontal cortex. One potential reason for hallucinations and the altered consciousness that we see is because activation of these receptors causes stimuli that were previously not able to be recognized by us now to cause neuronal responses, meaning that we pick up on every little thing that happens around us that we previously weren’t aware of. Cool, right? 

It is alarmingly obvious that changes in consciousness can be studied, due to the help of modern neuroscience. Concepts like neuroplasticity, sporogenesis, and psychoactive drugs provide a clear study of how our consciousness can change throughout our lives. Interestingly, psychoactive drugs like psilocybin and ketamine have been propelled into the mainstream in recent years, being explored for their role in treating disorders like depression (Psiuk et al., 2022). 

Conclusion 

In our daily lives, we may perceive our consciousness as being unchanging. In actuality, countless systems can influence how we perceive our environments despite us not being able to actively be aware of them. They actively rewire our neural circuitry to optimize the way we interact with the world around us. If you had to leave this article with a single thought…be grateful that your brain is taking care of you in more ways than you could imagine.

Sources

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Psiuk, D., Nowak, E. M., Dycha, N., Łopuszańska, U., Kurzepa, J., & Samardakiewicz, M. (2022). Esketamine and Psilocybin—The Comparison of Two Mind-Altering Agents in Depression Treatment: Systematic Review. International Journal of Molecular Sciences, 23(19). https://doi.org/10.3390/ijms231911450 

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