-Research News '

Is Your Brain Really Necessary?

John Lorber, a British neurologist, claims that somepatients are more normal than would be inferred from their brain scans

"Professor John Lorber has a facilityfor making doctors sit up and think abouthallowed concepts," writes Adrian Bow-er, a neuroanatomist at Sheffield Univer-sity, England, where Lorber holds aresearch chair in pediatrics. "The hu-man brain is the current object of hischallenging speculation," continuesBower, referring to his colleague's re-cent propositions concerning hydroceph-alus, or water on the brain. For instance,Lorber was not jesting totally when headdressed a conference of pediatricianswith a paper entitled "Is your brain real-ly necessary?" Lorber believes that hisobservations on a series of hydro-cephalics who have severely reducedbrain tissue throws into question manytraditional notions about the brain, bothin clinical and scientific terms.

"There's a young student at this uni-versity," says Lorber, "who has an IQof 126, has gained a first-class honors de-gree in mathematics, and is socially com-pletely normal. And yet the boy has vir-tually no brain." The student's physicianat the university noticed that the youthhad a slightly larger than normal head,and so referred him to Lorber, simplyout of interest. "When we did a brainscan on him," Lorber recalls, "we sawthat instead of the normal 4.5-centimeterthickness of brain tissue between theventricles and the cortical surface, therewas just a thin layer of mantle measuringa millimeter or so. His cranium is filledmainly with cerebrospinal fluid."

This is dramatic by any standards, andLorber clearly enjoys retailing the story.But, startling as it may seem, this case isnothing new to the medical world."Scores of similar accounts litter themedical literature, and they go back along way," observes Patrick Wall, pro-fessor of anatomy at University College,London, "but the important thing aboutLorber is that he's done a long series ofsystematic scanning, rather than justdealing with anecdotes. He has gathereda remarkable set of data and he challeng-es, 'How do we explain it?' "How can someone with a grossly re-

duced cerebral mantle not only moveamong his fellows with no apparent so-cial deficit, but also reach high academicachievement? How is it that in some hy-

drocephalics whose brains are severelydistorted asymmetrically, the expectedone-sided paralysis is typically absent?And how is one to interpret the apparentrestoration to normality of a hydro-cephalic brain following a shunt opera-tion? These are the challenges that Lor-ber is proffering his neurology col-leagues.Lorber came to make his observations

on hydrocephalus through his in-volvement with assessment and treat-ment of spina bifida, a congenital condi-tion in which the spinal column fails tofuse completely, leaving nerve tissueperilously exposed. The great majorityof patients with spina bifida also sufferfrom hydrocephalus.

Although the origins of hydrocephalusare to some degree shrouded in mystery,it is clearly associated with a disturbanceof the circulation of cerebrospinal fluidthrough a system of channels and reser-voirs, or ventricles, in the brain. Backpressure apparently develops, and thismay balloon the ventricles to many timestheir normal size, so pressing the over-lying brain tissue against the cranium. Inyoung children, whose skulls are stillmalleable, one obvious consequence canbe a grossly enlarged head. Additionally,this physical assault from within leads toa real loss of brain matter. It is thereforenot surprising that many hydrocephalicssuffer intellectual and physical dis-abilities. What is surprising, however, is

Third

Cerebral ventriclesTwo hornlike lateral ventricles drain into acommon third ventricle which in its turn leadsto a common fourth ventricle. Cerebrospinalfluidflows from the lateral ventricles, throughthe third and fourth ventricles, leading to a"sink" along the midline at the top of thehead and to a channel that runs down thespinal column.

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that a substantial proportion of patientsappear to escape functional impairmentin spite of grossly abnormal brain struc-ture."The spina bifida unit at the Chil-

dren's Hospital here in Sheffield is one ofthe largest in the world," explains Lor-ber, "and this gives us an opportunity tomake many observations. Since the in-troduction of the safe, noninvasive brainscanning technique just a few years agowe have done more than 600 scans on pa-tients with hydrocephalus." Lorber di-vides the subjects into four categories:those with minimally enlarged ventri-cles; those whose ventricles fill 50 to 70percent of the cranium; those in whichthe ventricles fill between 70 and 90 per-cent of the intracranial space; and themost severe group, in which ventricle ex-pansion fills 95 percent of the cranium.Many of the individuals in this lastgroup, which forms just less than 10 per-cent of the total sample, are severely dis-abled, but half of them have IQ's greaterthan 100. This group provides some ofthe most dramatic examples of apparent-ly normal function against all odds.Commenting on Lorber's work, Ken-

neth Till, a former neurosurgeon at theGreat Ormond Street Hospital for SickChildren, London, has this to say: "In-terpreting brain scans can be very tricky.There can be a great deal more brain tis-sue in the cranium than is immediatelyapparent." Till echoes the cautions ofmany practitioners when he says, "Lor-ber may be being rather overdramaticwhen he says that someone has 'virtuallyno brain.' " Lorber acknowledges theproblem of.interpretation of brain scans,and he counters Till's remarks by insist-ing, "Of course these results are dramat-ic, but they're not overdramatic. Onewould not make the claim if one did nothave the evidence."A major obstacle in this work is the

difficulty of obtaining the kind of quan-titative data that would be expected in ascientific investigation of, say, ratbrains. "I can't say whether the mathe-matics student has a brain weighing 50grams or 150 grams, but it's clear that itis nowhere near the normal 1.5 kilo-grams," asserts Lorber, "and much ofthe brain he does have is in the more

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primitve deep structures that are rela-tively spared in hydrocephalus."Lbrber concludes from these observa-

-tions that "there must be a tremendousamount of redundancy or spare capacityin the brain, just as there is with kidneyand liver." He also contends that "thecortex probably is responsible for a greatdeal less than most people imagine."These are two areas of considerable dis-pute in neurobiology. Wall lends supportfor this second point. "One reason whyresults such as Lorber's have been ne-glected for so long is because of the im-plied attack on the predominance of thecerebral cortex," suggests Wall. "Forhundreds of years neurologists have as-sumed that all that is dear to them is per-formed by the cortex, but it may well bethat the deep structures in the brain car-ry out many of the functions assumed tobe the sole province of the cortex." Helikens the cortex to a "reference library"that may be consulted from time to time.Norman Geschwind, a neurologist at

the Beth Israel Hospital, Boston, strikesa different note. "Deep structures in thebrain are undoubtedly important formany functions," he agrees, "but I don'tbelieve the explanation that the cortexdoes far less than we think is verysound." And neither does David Bow-sher, professor of neurophysiology atLiverpool University, England: "I don'tthink we attribute more to the cortexthan it deserves." Bower, however,takes the middle ground, with the sug-gestion that "the deep structures are al-most certainly more important than iscurrently thought."On the question of the brain's spare

capacity there is equal contention. "Totalk of redundancy in the brain is an in-tellectual cop-out to try to get roundsomething you don't understand," statesWall. Geschwind agrees: "Certainly thebrain has a remarkable capacity for reas-signing functions following trauma, butyou can usually pick up some kind ofdeficit with the right tests, even after ap-parently full recovery." However, ColinBlakemore, professor of physiology atOxford University, England, sees sparecapacity as an important quality of thehuman brain. "The brain frequently hasto cope with minor lesions and it's cru-cial that it can overcome these readily,"he says; "there may be some reorganiza-tion of brain tissue, but mostly there's areallocation of function."

It is perhaps significant that many ofthe instances in which gross enlargementof cerebral ventricles is compatible withnormal life are cases where the conditiondevelops slowly. Gross surgical lesionsin rat brains are known to inflict severe12 DECEMBER 1980

Scans of normal and hydrocephalic brainsA horizontal scan across the brain shows the ventricles as narrow slits in a normal individualand large cavities in a hydrocephalic patient.

functional disruption, but if the samedamage is done bit by bit over a long pe-riod of time, the dysfunction can be mini-mal. Just as the rat brains appear to copewith a stepwise reduction of availablehardware, so too do the human brains insome cases of hydrocephalus.Another subgroup of some curiosity in

Lorber's subjects are those people inwhom expansion of the ventricles is re-stricted to just one side of the brain. "I'venow seen more than 50 cases of asym-metric hydrocephalus," says Lorber,"and the interesting thing is that only aminority of these individuals show theexpected and long-cherished neurologi-cal finding of paralysis with spasticity onthe opposite side of the body." To makematters even more puzzling, one individ-ual in the group has enormously enlargedventricles on the same side as his spasticparalysis. "This is exactly the oppositeto all that we learnt in medical school,"reports Lorber with obvious glee. Theseobservations are cogent support forBower's comment that "the concept ofcontralateral control is the least secureof all our concepts about brain organiza-tion and function."

Lorber's extensive series of brainscans stands in marked contrast with thedearth of information on the fine struc-ture of hydrocephalic human brains. "Itis crucial to know about the histologicalstate of the brains of these functionallynormal hydrocephalic patients," re-marks Lorber, "but how am I to have ac-cess to such material, given the ethicalbarriers to scientific research on pa-tients?" Inadequate though it is, the nextbest thing is experimental work on ani-mals.A group of researchers based at the

New York University Medical Centerhas assembled a picture of the histologi-cal changes associated with hydrocepha-lus through experimental induction of

the condition in cats. The group also ob-served the changes in tissue structurefollowing the implantation of a shunt, theexperimental equivalent to the normaltreatment of hydrocephalus in humans.Speaking for the group, Fred Epsteinsays the following: "Hydrocephalus isprincipally a disease of the white matter.As the ventricles enlarge the layers of fi-bers above them begin to be stretchedand very quickly they are disrupted, withthe axons and the myelin sheaths sur-rounding them breaking down. Even insevere and extended hydrocephalus,however, the nerve cells in the gray mat-ter were remarkably spared, thougheventually there began to be a loss heretoo." The sparing of the gray mattereven in severe hydrocephalus could gosome way to explaining the remarkableretention ofmany normal functions in se-verely affected individuals.

Crucial to the approach to treatment ofhydrocephalus is the brain's ability to re-cuperate following the release of fluidpressure when a shunt is implanted. Oneof the canons of neurobiology is that,once damaged, cells in the central ner-vous system are unable to repair them-selves. Does Lorber's work dent thishallowed concept too? "When you im-plant a shunt in a young hydrocephalicchild you often see complete restorationof overall brain structure, even in caseswhere initially there is no detectablemantle," claims Lorber. "There mustbe true regeneration of brain substancein some sense, but I'm not necessarilysaying that nerve cells regenerate," hesays cautiously; "I don't think anyoneknows fully about that."What, then, is happening when a hy-

drocephalic brain rebounds from being athin layer lining a fluid-filled cranium tobecome an apparently normal structurewhen released from hydrostatic pres-sure? According to Epstein and on the

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basis of his colleagues' observations onexperimental cats,- the term rebound apt-ly describes the reconstitution process,with stretched fibers shortening, thus di-minishing the previously expanded ven-tricular space. Within a short time scartissue forms, constructed from the glialcells that pack between the nerve cells."The reconstitution of the mantle," re-port Epstein and his colleagues, "doesnot result in the reformation of lost ele-ments, but rather in the formation of aglial scar and possibly a return to func-tion of the remaining elements."Lorber claims that his observations on

the dramatic recovery of severely af-fected young children imply that "clini-cians shouldn't give up in the face of anapparently hopeless case; a shunt opera-tion at an early stage has a good chanceof producing a normal individual." Inmild cases, or ones that develop slowlyand late, Lorber takes a different ap-proach. Citing the example of the mathe-matics student and others like him, heproposes that perhaps the surgical knifeshould be stayed, "because a shunt op-eration makes an individual forever de-

pendent on surgical care, and in any casemany of these subjects can lead perfectlynormal lives." The difference is betweenthe acute and chronic conditions.These statements are certain not to go

unchallenged, partly because there is amultiplicity of opinions about appropri-ate treatment of hydrocephalus and part-ly because it is Lorber who is makingthem. Lorber is no stranger to controver-sy. Just a few years ago he caused astorm in the medical world by suggestingthat it is not always medically right to ad-minister extensive treatment to some in-fants with spina bifida. His experiencehad taught him that the consequences insome severe cases were simply not toler-able, either to the patient or to the imme-diate family. This position continues tobe hotly debated, but Lorber's ideas arebeginning to receive favorable consid-eration, particularly in the United King-dom (see 12 September 1980, p. 1216).What of the Lorber approach to hy-

drocephalus? "His attitude is based onmany years of clinical experience," saysGerald Hochwald of New York Univer-sity Medical Center, "and it contains a

certain amount of value." Thoma~Mil-horat, a neurosurgeon at the Children'sHospital in Washington, D.C., voikesstrong support for Lorber, in spite ofmany differences of opinion. "I'm gladthere's a John Lorber," says Milhorat;"he could be more moderate in the wayhe expresses things, but a moderate viewwould not emerge if someone were notspeaking out strongly."As to the question "Is your brain real-

ly necessary?" Lorber admits that it isonly half serious. "You have to be dra-matic in order to make people listen,"concedes the tactician. Bower's answerto the tongue-in-cheek question is this:"Although Lorber's work doesn't dem-onstrate that we don't need a brain, itdoes show that the brain can work inconditions we would have thought im-possible." Bower occasionally com-plains that Lorber's style is less scien-tific than it might be. He concedes, how-ever, that "there are still many questionsto be answered about the human brain,and it has to be admitted that Lorber'sprovocative approach does make youthink about them."-ROGER LEWIN

Math and Sex: Are Girls Born with Less Ability?A Johns Hopkins group says "probably. " Others are not so sure

Throughout history there have beenvery few women mathematicians, andthis trend continues today. For example,when Edith Luchins, a mathematician atRensselaer Polytechnic Institute, andAbraham Luchins, a psychologist at theState University ofNew York at Albany,asked mathematicians to list five famouscontemporary women mathematicians,many could not. When Ravenna Helson,a psychologist at the University of Cali-fornia at Berkeley, set out in the 1960'sto study creative women mathemati-cians, she reported that there were sofew that she did not have to samplethem-she could study all of them.

Since creativity in mathematics seemsto be a talent, like musical or artistic abil-ity, the question has been, why are thereso few outstanding women mathemati-cians? Some researchers have said theanswer lies in nurture rather than nature.Mathematics is viewed as a "masculine"field of study, and girls are discouragedfrom developing their mathematical abil-ities. But Camilla Benbow and JulianStanley of Johns Hopkins Universityquestion this theory. They have evi-

dence that extraordinary mathematicaltalent may be less prevalent in girls thanin boys. The differences between theabilities of girls and boys are so striking,they say, that it is hard to imagine thatthey are entirely due to socialization. Bysticking their necks out in this way, Ben-bow and Stanley seem to be asking for anattack. But, says Stanley, "We want ourdata out in the public domain so theycan't be ignored."The data are from Stanley's mathe-

matics talent searches, the Study ofMathematically Precocious Youth. From1972 to 1979, Stanley and his associatesconducted six talent searches, lookingfor 7th and 8th graders who scored in atleast the upper 2 to 5 percent in standard-ized mathematics achievement tests,such as the Iowa Tests of Basic Skills.They found 10,000 children, 43 percentof whom were girls, and invited them totake the mathematics and verbal por-tions of the Scholastic Aptitude Tests(SAT). Those who did extremely well onthe math portion were encouraged totake accelerated mathematics courses atJohns Hopkins. (Benbow and Stanley dis-

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cuss their data on page 1262 of this issue.)Stanley contends that the math SAT

serves as an aptitude test when given to7th and 8th graders because they havenot been formally taught the principlesthat underlie the math problems. If theycan do the problems, they must have un-usual abilities.

In 1980, the Johns Hopkins group ex-panded its talent search and changed itseligibility criteria. Any 7th grader whoscored in the 97th percentile or above inany standardized achievement test-whether the high score was in a mathsection or a verbal section or was a com-bined score-was invited to take the ver-bal and math SAT's. The researchersfound 10,000 such students, making thetotal tested thus far 20,000.Every year, the Johns Hopkins group

has found that the girls and boys doequally well on the verbal SAT's but theboys do significantly better on the mathSAT's. For example, more than twice asmany boys as girls had math scoresgreater than 500. The greatest dif-ferences were between the top-scoringgirls and boys. And in every talent

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