In the book What to Say When You Talk to Yourself, Shad Helmstetter briefly mentions that “researchers discovered that people who typically think positively actually grow more neurons in the left prefrontal cortex of their brain.” He then goes on to claim that the left prefrontal cortex is involved in seeking alternative solutions to problems and keeping us balanced.

This passage caught my attention. If this is really the case, it would mean that positive self-talk is like a superpower and that, simply by engaging in it, we can have a lot of positive effects.

I decided that I wanted to read the literature supporting these claims. Unfortunately, the book is more motivational than scientific, so it provides no direct references to the literature. On the other hand, it was published in 1986, and I assume that we have made progress in brain imaging and measuring brain activity over the last 40 years. It therefore seemed more interesting to look at recent literature.

What the literature says

Regarding the latter claim, I read:

  1. Frontal EEG asymmetry as a moderator and mediator of emotion
  2. Rostral and caudal prefrontal contribution to creativity: A meta-analysis of functional imaging data

Both papers support the claim that the left prefrontal cortex contributes to creative thinking. The second paper states:

“The lateral PFC appeared to be organized along a rostro-caudal axis, with rostral regions involved in combining ideas creatively and more posterior regions involved in freely generating novel ideas.”

I could not find any study supporting the claim that the left prefrontal cortex develops additional neurons, in other words, that it undergoes neuroplastic changes. What I found instead are evidence of increased activity in the left prefrontal cortex, as reported in these studies:

  1. The Psychophysiological Effects of Self-Talk
  2. The Level of Self-Esteem May Influence the Effect of Positive Self-Statements: An EEG Alpha Asymmetry Pilot Study

Conclusion

To sum up, the literature confirms both a correlation and a causal relationship between self-talk and increased neural activity. The neuroplasticity claimed by the book is nowhere to be found. On the other hand, it seems to be widely accepted that continuous activity in a region leads to the formation of more synapses in the region.

I would say that the claim is too loosely worded and should be stated differently, but its meaning is sound after all. Amazing!