Neuroscience explanations

Although neuroscience studies are incredibly diverse, one way to summarize them is as follows: “Area or circuit X is involved in behavior Y” (where a circuit is a group of areas). A lesion study might determine that patients with damage of the so-called cortex of the anterior insula have the ability to quit smoking easily, without relapse, leading to the conclusion that the insula is a critical substrate in the addiction to smoking (1). Why? Quitting is hard in general, of course. But it turns out to be easy if one’s anterior insula is nonfunctional. It’s logical, therefore, to surmise that, when intact, this region’s operation somehow promotes addiction. An activation study using functional MRI might observe stronger signals in parts of the visual cortex when participants view pictures of faces compared to when they are shown many kinds of pictures that don’t contain faces (pictures of multiple types of chairs, shoes, etc.). This could prompt to the suggestion that this part of the visual cortex is important for the perception of faces. A manipulation study could enhance activity in prefrontal cortex in monkeys, and observe an improvement in tasks that require careful attention to visual information.

Many journals require “significance statements” in which authors summarize the importance of their studies to a broader audience. In the instances of the previous paragraph, the authors could say something like this: 1) the insula contributes to conscious drug urges and to decision-making processes that precipitate relapse; 2) the fusiform gyrus (the particular area of visual cortex that responds vigorously to faces) is involved in face perception; and 3) the prefrontal cortex enhances performance of behaviors that are challenging and require attention.

Figure . Because little is known about how brain mechanisms bring about behaviors, neuroscientists permeate their papers with “filler” verbs as listed above, most of which do not add substantive content to the statements made. Figure from Krakauer, J. W., Ghazanfar, A. A., Gomez-Marin, A., MacIver, M. A., & Poeppel, D. (2017). Neuroscience needs behavior: correcting a reductionist bias. Neuron, 93(3), 480-490.

The examples above weren’t gratuitous; all were important studies published in respected scientific journals (2). Although these were rigorous experimental studies, they don’t quite inform about the underlying mechanisms (3). In fact, if one combs the peer-reviewed literature, one finds a plethora of filler terms – words like “contributes”, “involved”, and “enhances” above (see Figure) – that stand in for the processes we presume did the “real” work. This is because, by and large, neuroscience studies don’t sufficiently determine, or even strongly constrain, the underlying mechanisms that link brain to behavior.

Refs:

[1] Naqvi et al. (2007).

[2] Addiction: Navqi et al. (2007); faces: Kanwisher et al. (1997); attention: Noudoost et al. (2010).

[3] But the stimulation studies described by Noudoost et al. (2010) come closest.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: