"Long before it's in the papers"
January 27, 2015


Baby temperament found to predict adult brain structure

Jan. 9, 2010
Special to World Science  

In a study that could help clar­i­fy the com­plex rela­t­ion­ships be­tween the brain, en­vi­ron­ment and be­hav­ior, re­search­ers have found that four-month-old in­fants’ tem­per­a­ment pre­dicts some as­pects of their brain struc­ture 18 years lat­er.

Sci­en­tists at Mas­sa­chu­setts Gen­er­al Hos­pi­tal in Charles­town, Mass., stud­ied 76 eighteen-year-olds that, at four months of age, had been cat­e­go­rized in pre­vi­ous re­search as “high-reac­tive” or “low-reac­tive.” High-reac­tive gen­er­ally means shy and in­hib­ited, while low-reac­tive means out­go­ing and un­in­hib­ited.

The in­ves­ti­ga­tors used a form of brain scan­ning known as struc­tur­al mag­net­ic res­o­nance im­ag­ing, which em­ploys mag­net­ic field and ra­di­o waves to pro­duce clear and de­tailed pic­tures of the brain.

Adults with a low-reac­tive in­fant tem­per­a­ment showed great­er thick­ness in a brain struc­ture called the left or­bitofrontal cor­tex, the sci­en­tists found. This re­gion has been im­pli­cat­ed in pro­cess­ing of emo­tions and of self-monitoring.

On the oth­er hand, the adults pre­vi­ously cat­e­go­rized as high-reac­tive, showed great­er thick­ness in the right ven­tro­me­dial pre­fron­tal cor­tex, the re­search­ers re­ported. This brain ar­ea has been linked to im­pulse con­trol, with great­er size linked to more self-con­trol, and with the anal­y­sis of so­cial situa­t­ions.

“To our knowl­edge, this is the first demon­stra­t­ion that tem­per­a­mental dif­fer­ences meas­ured at four months of age have im­plica­t­ions for the ar­chi­tec­ture of hu­man cer­e­bral cor­tex last­ing in­to adult­hood,” the re­search­ers wrote in the stu­dy, pub­lished in the Jan­u­ary is­sue of the jour­nal Ar­chives of Gen­er­al Psy­chi­a­try. The cer­e­bral cor­tex is a lay­er of brain cells cov­er­ing the sur­face of the brain and linked to ad­vanced think­ing func­tions.

High-reac­tive in­fants are char­ac­ter­ized at age four months by vig­or­ous ac­ti­vity and cry­ing in re­sponse to un­fa­mil­iar stim­u­li, ac­cord­ing to the au­thors, Carl Schwartz, di­rec­tor of the hos­pi­tal’s De­vel­op­men­tal Neuroim­ag­ing and Psy­cho­pa­thol&sh Re­search Lab­o­r­a­to­ry, and col­leagues. Low-reac­tive in­fants by con­trast stay more still and cry less in re­spose to the same situa­t­ions.

High-reac­tive in­fants tend to be­come be­hav­iorally in­hib­ited in the sec­ond year of life, while low-reac­tive in­fants tend the op­po­site way, the au­thors added.

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In a study that could help clarify the complex relationships between the brain, environment and behavior, researchers have found that four-month-old infants’ temperament predicts some aspects of their brain structure 18 years later. Scientists at Massachusetts General Hospital in Charlestown, Mass., studied 76 eighteen-year-olds that, at four months of age, had been categorized in previous research as “high-reactive” or “low-reactive.” High-reactive generally means shy and inhibited, while low-reactive means outgoing and uninhibited. The investigators used a form of brain scanning known as structural magnetic resonance imaging, which employs magnetic field and radio waves to produce clear and detailed pictures of the brain. Adults with a low-reactive infant temperament showed greater thickness in a brain structure called the left orbitofrontal cortex, the scientists found. This region has been implicated in processing of emotions and of self-monitoring. On the other hand, the adults previously categorized as high-reactive, showed greater thickness in the right ventromedial prefrontal cortex, the researchers reported. This brain area has been linked to impulse control, with greater size linked to more self-control, and with the analysis of social situations. “To our knowledge, this is the first demonstration that temperamental differences measured at four months of age have implications for the architecture of human cerebral cortex lasting into adulthood,” the researchers wrote in the study, published in the January issue of the journal Archives of General Psychiatry. The cerebral cortex is a layer of brain cells covering the surface of the brain and linked to advanced thinking functions. High-reactive infants are characterized at age four months by vigorous activity and crying in response to unfamiliar stimuli, according to the authors, Carl Schwartz, director of the hospital’s Developmental Neuroimaging and Psychopathology Research Laboratory, and colleagues. Low-reactive infants by contrast stay more still and cry less in respose to the same situations. High-reactive infants tend to become behaviorally inhibited in the second year of life, while low-reactive infants tend the opposite way, the authors added.