Neurosurgery – Contemplation of the Future

When I was a medical student 42 years ago my neurological textbooks were replete with diagrams of the motor, sensory, visual, and speech areas of the cerebral cortex. It occurred to me then that perhaps the viscera might also have cortical representation and therefore why not try to find out if this were so? Sad to say I was dissuaded from investigative attempts on the grounds that time in medical school should be spent only on learning. (In this respect, I would urge that any of you with promising investigative ideas should put them to the test and not be persuaded to forget them. For sad experience has shown that if you don’t do the job, someone else will!). Since my early days, much has been learned about the visceral representation in the cortex of the brain, to part of which I eventually contributed. It is now known, for example, that the vagus nerve nucleus has a representation in the subfrontal cortex, bladder and bowels in the juxtamotor cortex, cardiac and respiratory control in the cingulate and medial temporal cortex, and sex organs also in the latter. Pupillary changes may be elicited by stimulating the anterior cingulate gyri, intussception by stimulating posterior cingulate gyri, while blood pressure alterations may be induced on stimulation of numerous parts of the cerebral cortex. All this adds up to the now well-known fact that in addition to a motor and sensory cortex, there is also what might be termed a “ visceral brain” in man and beast(9). Copyright Royal Medical Society. All rights reserved. The copyright is retained by the author and the Royal Medical Society, except where explicitly otherwise stated. Scans have been produced by the Digital Imaging Unit at Edinburgh University Library. Res Medica is supported by the University of Edinburgh’s Journal Hosting Service: http://journals.ed.ac.uk ISSN: 2051-7580 (Online) ISSN: 0482-3206 (Print) Res Medica is published by the Royal Medical Society, 5/5 Bristo Square, Edinburgh, EH8 9AL Res Medica, Spring 1972, 6(6): 18-20 doi:10.2218/resmedica.v6i6.885 NEUROSURGERY CONTEMPLATION


NEUROSURGERY -CONTEMPLATION
OF THE FUTURE J-Lawrence Pool.M.D.
W h e n I was a m edical student 42 years ago m y neurological textbooks were replete with diagram s o f the m otor, sensory, visual, and speech areas of the cerebral cortex.It occur red to m e then that perhaps the viscera m ight also have cortical representation and therefore why not try to find out if this were so?Sad to say I was dissuaded from investigative attem pts on the grounds that tim e in m edical school should be spent only on learning.(In this respect, I would urge that any of you with prom ising investigative ideas should put them to the test and not be persuaded to forget them .F o r sad experience has shown that if yon d on't do the job, som eone else w ill!) Since m y early days, m uch has been learned about the visceral representation in the cortex of the brain, to part of w hich I eventually contributed.It is now know n, for exam ple, that the vagus nerve nucleus has a representation in the subfrontal cortex, bladder and bowels in the juxtam otor cortex, cardiac and respiratory control in the cingulate and m edial tem poral cortex, and sex organs also in the latter.Pupillary changes m ay be elicited b y stim ulating the anterior cingulate gyri, intussception by stim ulating posterior cingulate gyri, while blood pressure alterations m ay be induced on stim ulation of num erous parts of the cerebral cortex.A ll this adds up to the now well-known fact that in addition to a m otor and sensory cortex, there is also w hat m ight be term ed a " visceral brain" in man and b east (9).
M o re recent and on-going studies in our laboratories(3) suggest there m ay also be what m ight b e called a " m etabolic brain" .F o r ex am ple, stim ulation o f certain discrete areas within the hypothalam us and m ore rem ote but related parts of the brain b y m eans o f microelectrodes, in cats and other anim als, induces an alm ost im m ediate and m assive m obilization of fat, after a m eal, into the circulating blood, and at the same tim e causes the blood to clot w ithin a m atter of seconds instead of several m inutes.H ere then is a possible m echanism by which coronary or cerebral vascular accidents m ay be produced.A stressful situation follow ing a heavy m eal m ay, via hypothalam ic m edi ation, cause a dram atic increase in fat in the circulation.T h is m obilization of fats increases blood viscosity and the blood tends to clot rapidly.T h e com bination o f these two factors w ithin a narrowed sclerotic coronary or cerebral artery could obviously lead to its occlusion.T h is prelim inary work, although not yet de finitive, suggests how the brain m ay play a role in causing a serious system ic disease, such as a stroke or coronary attack.
O ther work in our m edical center has indi cated the presence o f a new horm one-like protein, derived from the hypothalam o-pitu itary system, which appears essential for synchronous peristalsis of the gut.Prelim inary studies suggest that this horm one is deficient in persons afflicted w ith gastro-intestinal dis orders such as ulcerative colitis, and that the latter can be relieved in som e cases by adm in istration o f this horm one (6).T h is perhaps is another exam ple o f m etabolic control o f body organs by the brain.
M ore fam iliar exam ples are fluid, electrolyte and sugar regulation b y hypothalam ic and brain stem nuclei, and endocrine control by the hypothalam ic-m edial tem poral-pituitary axis.R ecen t w o rk (12) indicates th at even th e pul m onary circulation m ay be drastically altered by the autonom ic nervous system activity.
W h a t has all this to do w ith the future?Increasing evidence points to the influence of the brain in regulating system ic activity.I would suggest that perhaps all body functions, m etabolic, hem atologic, endocrine, visceral, autonom ic and even pulm onary circu lation (12) m ay be controlled or regulated by the brain.
Further efforts should be made, I feel, to understand how the brain and its chemistry affects the various moods and emotions whose aberrations can lead to mental illness, includ ing schizophrenia(I0).A good deal, of course, is known about the anatomy of these circuits such as that of the limbic system and its spe cific thalamic and hypothalamic links.The future, I would suggest, offers the possibility of a brand new and far more promising kind of brain-mapping, based on the well established fact that various cell types of the central ner vous system, be they neurons or glial cells, have individual biochemical characteristics with respect to their nucleic acids, organelles, en zyme systems and synaptic transmitters.A dramatic example of this possibility is afforded by the fluorescent histochemical technique developed by Falck and Owman for detecting monoamine -containing nerve terminals(4).This tool has already afforded us new insights into the function of the nigral-straital system that was impossible by conventional histo logical methods.The excitement generated by each new discovery in the metabolic pathways of L -DO PA, and the therapeutic success of this amine, may well be duplicated when more is understood about the function of other amines, particularly norepinephrine.Sophisticated application of radioactive tagging techniques offer a new method of biochemical " brain-mapping" .In this manner we can detect, for instance, transneuronal trans fer of possible trophic substances in the central nervous system (5) and the differential up-take of steroids by various portions of the brain.This work has underlined the importance of temporal lobe structures in regulation of both cortical and estrogen function.These tech niques may also further our knowledge of the metabolism of metal in the brain.Copper, lead, tin, mercury, manganese and lithium all have been linked to certain changes in brain and mental function.The recent work show ing amelioration or control of manic-depressive states by administration of lithium carbonate indicates that investigation along these lines should also be rewarding.
Understanding of these biochemical-neural circuits could be important not only for a better understanding and therefore therapy of the usual run of mental and emotional illnesses, but also for those unfortunates plagued by life-long psychosomatic symptoms.The latter too often have been tossed off by our psychi atric brethren as being purely psychogenic in origin.Perhaps so, but it does seem that such symptoms may be truly organic in the sense that they become embedded in brain circuits as part of a self-inflicted conditioned reflex.(And at this point I must confess parenthe tically that there is a very thin line between what some would call a psychogenic and others an organic pattern.)The main point to be made, I suggest, is that most psychosomatic complaints relate to the autonomic nervous system : stomach aches, anorexia, palpitations, sweating, a dry mouth, fatigue, constipation and perhaps sundry aches and pains including headache.Too little attention has been paid to a possible organic aetiology of such symp toms.Recent studies have shown that rats have so slowed their heart that they actually died of cardiac arrest.These and other experi ments(3), indicating that cerebral control and conditioning is possible for autonomic nervous functions, suggest that psychosomatic com plaints may likewise have become ingrained, conditioned reflexes.Experimental mapping of the involved circuits could, in the future, perhaps lead to specific stereotaxic method of relieving severe psychosomatic symptoms.
And finally, with reference to what Bell (1816) called hypochondriacs, which I suspect were often what we would call " psychosomatic'' patients, he wrote as follows: (1) " In the Hypochondriac's feelings all is not imagination.Pains and odd sensations, attributable to external and remote parts, do actually proceed from the disturbance of internal nerves."I would heartily second these prophetic remarks and suggest pursuit of brain mapping with this in mind.For it is clear we do not begin to know all we should about the nervous system.M y orthopedic colleague, Professor Andrew Bassett, and others(2) have, for example, discovered that the internal as well as external parts of all bones of the body, in cluding every Haversian canal, have a nerve supply.Where do these' nerves go and what is their purpose?Is their role sensory, meta bolic or perhaps trophic?Do they, like other nerves, enjoy cortical representation?Could it be, as your Dr. William Cullen (1710-1790) taught in 1760, that the normal state of the body is determined by " nervous energy" from the nervous system and affected by external stimuli (11)?These are additional questions for the future.
There are many other topics one could cite that need attention in the future.Suffice it to say in closing that some of the more im portant include microsurgery to improve the circulation of the diseased brain; a better understanding and hence better treatment of some of the still mysterious forms of hydro cephalus; and perhaps the development of special techniques (7'8) or even implanted micro-electrical circuits fitted with miniature computers, to enable paraplegics to walk, and, as some are already attempting, to enable the blind to see.