How our viscera influence our brain and behavior

I want to pass on this fascinating and useful open source review by Critchley and Harrison in the journal Neuron. Having just had the flu, I found their presentation of visceral regulation of sickness behaviors very relevant! The article is worthwhile especially for the summary figures showing functional and anatomical pathways. (I resist the urge to paste them into this post, you can look at them by clicking on the link above. Here is their abstract:

Mental processes and their neural substrates are intimately linked to the homeostatic control of internal bodily state. There are a set of distinct interoceptive pathways that directly and indirectly influence brain functions. The anatomical organization of these pathways and the psychological/behavioral expressions of their influence appear along discrete, evolutionarily conserved dimensions that are tractable to a mechanistic understanding. Here, we review the role of these pathways as sources of biases to perception, cognition, emotion, and behavior and arguably the dynamic basis to the concept of self.

And, two clips from the text:

The internal state of the body motivates our desire to walk in the shade on a warm summer’s day and inhibits the desire to eat or socialize when feeling off-color. Communication from the viscera to brain is continuous and pervasive, yet we rarely give it a second thought. Visceral fluctuations and reactions accessible to introspective appraisal represent only the visible tip of the iceberg.

A comprehensive understanding of the integration of internal bodily signals in health is ultimately required for effective management of physical and psychological symptoms in illness. Such a goal can only be achieved through coordinated experimental approaches and perhaps a move away from treating physiological changes as irrelevant confounds in neuropsychological experiments. Together, these observations make “us realize more deeply than ever how much of our mental life is knit up in our corporeal frame” (James, 1890).