How do we study complexity? Reductionism as one way to study complexity

How do we study complexity?
Reductionism as one way to study complexity 

Figure 1: Experimental paradigm for brain slice electrophysiology

The brain is incredibly complex, and one of the ways by which scientists study the brain (and other complex things) is a method called “scientific reductionism”. This method reduces complex entities to their essential parts and makes them, if not easier, then at least more manageable to study. For example, for my graduate work, we studied neuregulin, a substance found in the brain. We wanted to see whether (and how) it impacts synaptic plasticity [1] - the process by which the brain changes over time in response to experiences and external or internal influences. By looking at a specific neuronal circuit in a particular part of the brain (the hippocampus), we were able to confirm that neuregulin was involved in regulating synaptic plasticity. These results enabled us to hypothesize and plan future experiments to study how neuregulin may be impacted in epilepsy [1]. 

Scientists use specific tools to understand the brain in a reductionist manner. We used a technique called brain slice electrophysiology to understand how neuregulin impacts plasticity in the hippocampus. In the figure to the left, we can see a schematic representation of the experimental paradigm. The neuronal pathway in the hippocampus that we studied is shown in blue; the placement of the stimulating and recording electrodes is also shown (Figure 1).

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Figure 2: Diagram of the complexity in endocannabinoid signaling

Later, in a review that I contributed to, we looked at the role of exo- and endo-cannabinoids in mental health disorders [2]. Figure 2 is a diagrammatic representation of the complex relationship between endocannabinoid signaling and other systems such as the hypothalamic-pituitary-adrenal (HPA) axis and dopaminergic (DA) signaling. The endocannabinoid system also affects the Brain-Derived Neurotropic Factor (BDNF) system. Figure 2 shows that the unique placement of the endocannabinoid system may modulate its impact on effects of chronic stress, which may lead to depressive behavior [2]. 

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The benefit of scientific reductionism is that it allows us to study something as complicated as the brain by studying its individual parts. The hope is that understanding these individual parts will help us understand the whole brain. However, there are limitations of reductionism as well [3]. 
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It may be that the behavior of a system arises not from how the various parts of a system behave individually, but from how they interact. Reductionism assumes a certain model for how parts of a system interact, and this model may not be a good description of the system we’re trying to study. In other words, the complexity of some phenomena cannot be understood with a reductionist approach. We may think we achieve understanding, but the very act of dividing a complex problem into several simpler ones changes the complexity, and the new complexity is no longer reflective of the original condition [4]. One may be skeptical of the utility of studying activity at the neuronal level when we are trying to understand questions such as why we love someone, why nations wage wars, or why we feel the way we do when we listen to music from our childhood. 
 
So how do we study complexity? In his book “Reductionism in Art and Science”, Eric Kandel talks about how reductionism led to the evolution of modern art and a paradigm shift in artistic perspective from figurative art to modern art. He makes the point that modern art and the way we engage with it may provide us clues into how our brains function [5].
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Similarly, I wonder what kinds of knowledge we might gain from an in-depth study of the ways in which practitioners learn and engage with Bharatanatyam over years, and the ways in which the audience interacts with the form. Bharatanatyam integrates a multitude of aspects, e.g., facial movements, hand gestures, emotions, storytelling, the feeling of bhakti or devotion etc. A more detailed understanding of how we bring together these many things into a single art form may give us hints about how we integrate the seemingly disparate studies of individual aspects of the brain into a unified whole.

Literature cited:

1. Iyengar SS, Mott DD. Neuregulin blocks synaptic strengthening after epileptiform activity in the rat hippocampus Brain Res. 2008 May 7;1208:67-73.
2. Mannekote Thippaiah S, Iyengar SS, Vinod KY. Exo- and Endo-cannabinoids in Depressive and Suicidal Behaviors Front Psychiatry. 2021;12:636228.
3. Kaiser MI. The limits of reductionism in the life sciences Hist Philos Life Sci. 2011;33:453-476.
4. Shuttleworth M. Scientific Reductionism.Available at: https://explorable.com/scientific-reductionism. Accessed April 6, 2023. 
5. Eric.R. Kandel. Reductionism in Art and Brain Science: Columbia University Press 2018.