Neuroscience can (not) explain everything
Neuroscience’s calling as a supreme discipline with the ability to explain everything remains unbowed. It seems as if we are our brain. Colourful pictures of the sparkling network in our head serve as explanation for almost all human behaviour, characteristics and actions. Consequentially neuro-leadership, neuro-marketing, neuro-sales and the like are booming. But is the focus on the 86 billion neurons in our brain not too narrow to explain the complexity of our self?
What if of all things our intestinal tract was more important than it seemed until now? “You are what you eat” – maybe there is great truth in this old saying (see Enders, 2014). An at the same time daring and exciting hypothesis is, that personality is not exclusively located in the brain, but influenced significantly by little – not very presentable – inhabitants of our body: the gut bacteria.
For example, in an experiment of Irish scientists, mice fed with Latrobazillus Rahmnosus JB-1 – a gut friendly bacteria, showed more stamina than those deprived of this supplement (Bravo et al., 2011). Bercik et al. (2011) found even more surprising results exchanging enterobacetria of two different strains of mice: mice of the more exploratory strain now living with the bacteria of the other more anxious strain, showed anxious behaviour themselves and vice versa.
To draw conclusions from experiments with mice to our human behaviour and characteristics is of course a dared analogy. But in 2013 Tillisch et al. found promising evidence that this conclusion could be permissible: they showed that women drinking probiotic mix regularly for four weeks reacted less to negative emotional stimuli than those of the control group.
Evidence from studies investigating the correlation between chronic intestinal diseases and mental disorders also support the assumption that the intestine is of great importance for example for the origin of emotions (see Graff et al. 2009; Tache & Bernstein, 2009).
But still, a distinct direction of cause and effect or the possibility to influence emotions and cognitions by changing the gut microflora remains wild guess.
The research of the intestine-brain-axis is only at the beginning. But the already existing results are strong signals that we should question our brain-focused view of humans. We can look forward to completely new explanatory approaches and potential influence of emotions and cognition. Who knows, we might find trainings on Microbacterial Managing instead of Neuro-Leadership workshops shortly!
Although this exciting research area is evolving, there is one conclusion we can already draw: reality is complex and cross-linked. Only when combining gut and brain, intuition and ration, western and eastern approaches, can we achieve a meaningful whole.
Bravo et al. (2011). Ingestion of Lactobacillus strain regulates emotional behaviour and central GABA receptor expression in a mouse via the vagus nerve. Proceedings of the National Academy of Science U.S.A. 108, 16050–16055.
Bercik P. et al. (2011). The intestinal microbiota affect central levels of brain-derived neurotropic factor and behaviour in mice. Gastroenterology 141, 599–609
Cryan, J. F. & Dinan, T. G. (2012). Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour. Nature Reviews Neuroscience 13, 701-712.
dasgehirn.info: http://dasgehirn.info/entdecken/kommunikation-der-zellen/nervenzellen-im-gespraech-2218/ (letzter Zugriff am 19.12.2014)
Enders, J. (2014). Darm mit Charme. Alles über ein unterschätztes Organ. Berlin: Ullstein.
Graff, L. A., Walker, J. R. & Bernstein, C. N. (2009). Depression and anxiety in inflammatory bowel disease: a review of comorbidity and management. Inflamm. Bowel Dis. 15, 1105-1118.
Tache, Y. & Bernstein, C. N. (2009). Evidence for the role of the brain-gut axis in inflammatory bowel disease: depression as cause and effect? Gastroenterology 136, 2058-2061.
Tillisch, K. et al. (2013). Consumption of fermeted milk product with probiotic modulates brain activity. Gastroenterology 144, 1394-1401.