Theta synchronization during sustained anticipatory attention in infants over the second half of the first year of life

The neurophysiological basis of attention control has been investigated in infants during the second half of the first year of life. The marked improv ement of voluntary control of attention and action is known to occur during this age period. EEG was registered in 60 infants aged 8-11 months under t hree experimental conditions: (1) attention to an object in the visual fiel d (externally controlled attention or the 'baseline'); (2) anticipation of the person in the peek-a-boo game (internally controlled attention); and (3 ) attention to the 'reappeared' person in the peek-a-boo game ('control' co ndition). Spectral analysis of the data revealed sharp increase of the EEG theta activity (3.6-6.0 Hz) during internally controlled attention as compa red to the 'baseline' and the 'control' conditions. The theta 1 (3.6-4.8 Hz ) increase was maximal at frontal electrode sites. The reactivity of the fr ontal theta 1 during internally controlled attention differentiated subject s with different ability to maintain this type of attention. The theta 2 (5 .2-6.0 Hz) reactivity was maximal at right temporal electrode site and did not depend on the ability to maintain anticipatory attention. The data poin t to different functional significance of theta 1 and theta 2 rhythms in in fants. It was suggested that the frontal theta 1 synchronization in infants reflects activity of the anterior attention system subserving executive co ntrol of attention. The ability to maintain anticipatory attention increase d, whereas the frontal theta 1 synchronization decreased during the studied age period. There was the direct relationship between frontal theta 1 sync hronization and persistence of internally controlled attention in 8-month-o lds. On the contrary, at 9 and 10 months, these variables were inversely-re lated. There was no link between theta 1 reactivity and persistence of anti cipatory attention in 11-month-olds. It was suggested that the age-dependan t dynamic of the relationship between frontal theta 1 reactivity and attent ion behaviour reflects the maturational shift in the functioning of anterio r attention system. The shift leads to more economic and more efficient fun ctioning of this system. (C) 1999 Elsevier Science B.V. All rights reserved .