Sensorimotor modulation of mood and depression: an integrative review

Several lines of research on mood disorders reveal that depression involves a dysfunction in an affective fronto-limbic circuitry that involves the prefrontal cortices, the cingulate cortex, several limbic structures including the amygdala and the hippocampus, lower brainstem structures and the basal ganglia. In dealing with both depressive symptoms as well as their manifestation in the brain, clinical as well as basic research has emphasized mainly a top-down or central approach in elucidating the etiology of depression and its therapy. The present integrative review emphasizes the bottom-up or peripheral view of evaluating the impact of stimulation via sensory modalities or the motor system on the same circuitry in effecting mood regulation and possibly causing mood disorders, specifically depression. The paper shows that there is now a considerable accumulation of data from clinical observations as well as research with animal models to suggest that hypo- or hyper-activation of the sensory or the motor systems by manipulating visual, auditory, olfactory or gustatory inputs as well as physical exercise can have modulatory effects on mood and depressive symptoms. Moreover, depression in turn affects sensorimotor processing, resulting in an interaction that may further contribute to the aggravation of depressive symptoms. The paper also cites evidence that activation of the affective circuitry by central manipulations such as by means of deep brain stimulation has similar modulatory effects as peripheral stimulation on mood and depression. Finally, it is proposed that systematic investigations using animal models of depression on the impact of uni- or multisensory manipulation as well as of physical exercise may provide new insights into the etiology and treatment of depression in humans.