The theories of John Hughlings Jackson (1835–1911) on brain structure and function will be discussed in the light of earlier theories of the frontal lobes that influenced him. These included the works of Charles Darwin (1809–1882) and Herbert Spencer (1820–1903). Hughlings Jackson's Four Principles of Nervous Action were:

– evolution of nervous functions;

– hierarchy of those functions;

– negative and positive symptoms of dissolution;

– local and uniform dissolution.

Important principles were the hierarchical organisation of the central nervous system, with interactions between levels. The highest level was the prefrontal cortex. His ideas were better applied to the motor than the sensory system. Further he was concerned with movements rather than muscles.

Of considerable significance were ideas of inhibition and release, and that clinical signs of neurological injury involved both processes simultaneously. This led to concepts of positive and negative symptoms, which he opined were present in every case; lesions could never localise a function, but only degrade a system, and the clinical effects were a reflection of the continued level of activity of parts of the brain spared by the lesion.

His interests in philosophy led him to state there was no physiology of the mind any more than there was a psychology of the nervous system; he advocated the Doctrine of Concomitance and parallelism of mental and neural states.

Hughlings Jackson disagreed with the cerebral laterality ideas of Pierre Paul Broca (1824–1880). He was impressed by the work of the French anatomist and zoologist Luis Pierre Gratiolet (1815–1865) and advocated an important role for the right hemisphere in language. For Hughlings Jackson mentation was a “dual process, played out between the two hemispheres of the brain”. Finally, in the presentation there will be a brief note on the relationship between Jean-Martin Charcot (1825–1893) and Hughlings Jackson [1Dewhurst K. Hughlings Jackson on psychiatry  Oxford: Sandford (1982). 

Cliquez ici pour aller à la section Références, 2 Selected writings of John Hughlings Jackson London: Staples Press (1958). 

Cliquez ici pour aller à la section Références, 3Trimble M.R. The intentional brain  Baltimore: Johns Hopkins University Press (2016). 

Cliquez ici pour aller à la section Références].