Defining the neuro-circuits controlling the cardiovascular and respiratory responses to exercise in humans: use of functional neurosurgical and imaging techniques

David Paterson D.Phil D.Sc

Professor & Associate Head of Division (Education), Division of Medical Sciences, University of Oxford, UK.

Editor-in-Chief The Journal of Physiology

One hundred years ago in The Journal of Physiology, Krogh and Lindhard published a seminal paper highlighting the importance of the brain in the control of the cardio-respiratory system during exercise.

This lecture will review the historical developments that have taken place since 1913, and attempt to place the detailed neuro-circuitry thought to underpin the cardio-respiratory response into context by focusing on key structures that might form the command network.

With the advent of enhanced neuroimaging and functional neurosurgical techniques, a unique window of opportunity has recently arisen to target potential circuits in humans. Animal studies have identified a priori sites of interest in mid-brain structures, in particular the sub-thalamic locomotor region (STN) and the periaqueductal grey (PAG) that have now been recorded from in humans during exercise.

When all data are viewed in an integrative manner, the PAG, in particular the lateral PAG, and aspects of the dorsal lateral PAG, appear to be key communicating circuitry for 'central command'. Moreover, the PAG also fulfils many requirements of a command centre. It has functional connectivity to higher centres (dorsal lateral pre-frontal cortex), the basal ganglia (in particular the STN), and receives a sensory input from contracting muscle, but importantly, it sends efferent information to brain stem nuclei involved in cardio-respiratory control.